[Federal Register Volume 85, Number 21 (Friday, January 31, 2020)]
[Proposed Rules]
[Pages 5782-5901]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-00481]
[[Page 5781]]
Vol. 85
Friday,
No. 21
January 31, 2020
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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50 CFR Parts 218
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental
to the U.S. Navy Training and Testing Activities in the Mariana Islands
Training and Testing (MITT) Study Area; Proposed Rule
Federal Register / Vol. 85, No. 21 / Friday, January 31, 2020 /
Proposed Rules
[[Page 5782]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 218
[Docket No. 200109-0005]
RIN 0648-BJ00
Taking and Importing Marine Mammals; Taking Marine Mammals
Incidental to the U.S. Navy Training and Testing Activities in the
Mariana Islands Training and Testing (MITT) Study Area
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Proposed rule; request for comments and information.
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SUMMARY: NMFS has received a request from the U.S. Navy (Navy) to take
marine mammals incidental to training and testing activities conducted
in the Mariana Islands Training and Testing (MITT) Study Area. Pursuant
to the MMPA, NMFS is requesting comments on its proposal to issue
regulations and subsequent Letter of Authorization (LOA) to the Navy to
incidentally take marine mammals during the specified activities. NMFS
will consider public comments prior to issuing any final rule and
making final decisions on the issuance of the requested LOA. Agency
responses to public comments will be summarized in the notice of the
final decision. The Navy's activities qualify as military readiness
activities pursuant to the MMPA, as amended by the National Defense
Authorization Act for Fiscal Year 2004 (2004 NDAA).
DATES: Comments and information must be received no later than March
16, 2020.
ADDRESSES: You may submit comments on this document, identified by
NOAA-NMFS-2020-0006, by any of the following methods:
Electronic submission: Submit all electronic public
comments via the Federal e-Rulemaking Portal. Go to
www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2020-0006, click the
``Comment Now!'' icon, complete the required fields, and enter or
attach your comments.
Mail: Submit written comments to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service, 1315 East West Highway, Silver
Spring, MD 20910.
Instructions: Comments sent by any other method, to any other
address or individual, or received after the end of the comment period,
may not be considered by NMFS. All comments received are a part of the
public record and will generally be posted for public viewing on
www.regulations.gov without change. All personal identifying
information (e.g., name, address), confidential business information,
or otherwise sensitive information submitted voluntarily by the sender
will be publicly accessible. NMFS will accept anonymous comments (enter
``N/A'' in the required fields if you wish to remain anonymous).
Attachments to electronic comments will be accepted in Microsoft Word,
Excel, or Adobe PDF file formats only.
A copy of the Navy's application, NMFS' proposed and final rules
and subsequent LOA for the existing regulations, and other supporting
documents and documents cited herein may be obtained online at:
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems
accessing these documents, please use the contact listed here (see FOR
FURTHER INFORMATION CONTACT).
FOR FURTHER INFORMATION CONTACT: Stephanie Egger, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Purpose of Regulatory Action
These proposed regulations, issued under the authority of the MMPA
(16 U.S.C. 1361 et seq.), would provide the framework for authorizing
the take of marine mammals incidental to the Navy's training and
testing activities (which qualify as military readiness activities)
from the use of sonar and other transducers and in-water detonations
throughout the MITT Study Area. The Study Area includes the seas off
the coasts of Guam and the Commonwealth of the Northern Mariana Islands
(CNMI), the in-water areas around the Mariana Islands Range Complex
(MIRC), the transit corridor between the MIRC and the Hawaii Range
Complex (HRC), and select pierside and harbor locations. The transit
corridor is outside the geographic boundaries of the MIRC and
represents a great circle route across the high seas for Navy vessels
transiting between the MIRC and the HRC. The proposed activities also
include various activities in Apra Harbor such as sonar maintenance
alongside Navy piers located in Inner Apra Harbor.
NMFS received an application from the Navy requesting seven-year
regulations and an authorization to incidentally take individuals of
multiple species of marine mammals (``Navy's rulemaking/LOA
application'' or ``Navy's application''). Take is anticipated to occur
by Level A and Level B harassment incidental to the Navy's training and
testing activities, with no serious injury or mortality expected or
proposed for authorization.
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA direct the
Secretary of Commerce (as delegated to NMFS) to allow, upon request,
the incidental, but not intentional, taking of small numbers of marine
mammals by U.S. citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, the public is provided with notice of the
proposed incidental take authorization and provided the opportunity to
review and submit comments.
An authorization for incidental takings shall be granted if NMFS
finds that the taking will have a negligible impact on the species or
stocks and will not have an unmitigable adverse impact on the
availability of the species or stocks for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other means of effecting the least practicable adverse
impact on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of such species or stocks for
taking for certain subsistence uses (referred to in this rule as
``mitigation measures''); and requirements pertaining to the monitoring
and reporting of such takings. The MMPA defines ``take'' to mean to
harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or
kill any marine mammal. The Preliminary Analysis and Negligible Impact
Determination section below discusses the definition of ``negligible
impact.''
The NDAA for Fiscal Year 2004 (2004 NDAA) (Pub. L. 108-136) amended
section 101(a)(5) of the MMPA to remove the ``small numbers'' and
``specified geographical region'' provisions indicated above and
amended the definition of ``harassment'' as applied to a ``military
readiness activity.'' The definition of harassment for military
readiness activities (section 3(18)(B) of the MMPA) is (i) Any act that
injures or has the significant potential to
[[Page 5783]]
injure a marine mammal or marine mammal stock in the wild (Level A
Harassment); or (ii) Any act that disturbs or is likely to disturb a
marine mammal or marine mammal stock in the wild by causing disruption
of natural behavioral patterns, including, but not limited to,
migration, surfacing, nursing, breeding, feeding, or sheltering, to a
point where such behavioral patterns are abandoned or significantly
altered (Level B harassment). In addition, the 2004 NDAA amended the
MMPA as it relates to military readiness activities such that the least
practicable adverse impact analysis shall include consideration of
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
More recently, section 316 of the NDAA for Fiscal Year 2019 (2019
NDAA) (Pub. L. 115-232), signed on August 13, 2018, amended the MMPA to
allow incidental take rules for military readiness activities under
section 101(a)(5)(A) to be issued for up to seven years. Prior to this
amendment, all incidental take rules under section 101(a)(5)(A) were
limited to five years.
Summary and Background of Request
On February 11, 2019, NMFS received an application from the Navy
for authorization to take marine mammals by Level A and Level B
harassment incidental to training and testing activities (categorized
as military readiness activities) from the use of sonar and other
transducers and in-water detonations in the MITT Study Area over a
seven-year period beginning when the current authorization expires.
The following types of training and testing, which are classified
as military readiness activities pursuant to the MMPA, as amended by
the 2004 NDAA, would be covered under the regulations and LOA (if
authorized): Amphibious warfare (in-water detonations), anti-submarine
warfare (sonar and other transducers, in-water detonations), surface
warfare (in-water detonations), and other testing and training (sonar
and other transducers). The activities would not include any pile
driving/removal or use of air guns.
This will be the third time NMFS has promulgated incidental take
regulations pursuant to the MMPA relating to similar military readiness
activities in the MITT Study Area, following those effective from
August 3, 2010, through August 3, 2015 (75 FR 45527; August 3, 2010)
and from August 3, 2015 through August 3, 2020 (80 FR 46112; August 3,
2015). For this third rulemaking, the Navy is proposing to conduct
similar activities as they have conducted over the past nine years
under the previous rulemakings.
The Navy's mission is to organize, train, equip, and maintain
combat-ready naval forces capable of winning wars, deterring
aggression, and maintaining freedom of the seas. This mission is
mandated by Federal law (10 U.S.C. 8062), which requires the readiness
of the naval forces of the United States. The Navy executes this
responsibility by training and testing at sea, often in designated
operating areas (OPAREA) and testing and training ranges. The Navy must
be able to access and utilize these areas and associated sea space and
air space in order to develop and maintain skills for conducting naval
operations. The Navy's testing activities ensure naval forces are
equipped with well-maintained systems that take advantage of the latest
technological advances. The Navy's research and acquisition community
conducts military readiness activities that involve testing. The Navy
tests ships, aircraft, weapons, combat systems, sensors, and related
equipment, and conducts scientific research activities to achieve and
maintain military readiness.
The tempo and types of training and testing activities have
fluctuated because of the introduction of new technologies, the
evolving nature of international events, advances in warfighting
doctrine and procedures, and changes in force structure (e.g.,
organization of ships, submarines, aircraft, weapons, and personnel).
Such developments influence the frequency, duration, intensity, and
location of required training and testing activities, but the basic
nature of sonar and explosive events conducted in the MITT Study Area
has remained the same.
The Navy's rulemaking/LOA application reflects the most up-to-date
compilation of training and testing activities deemed necessary to
accomplish military readiness requirements. The types and numbers of
activities included in the proposed rule account for fluctuations in
training and testing in order to meet evolving or emergent military
readiness requirements. These proposed regulations would cover training
and testing activities that would occur for a seven-year period
following the expiration of the current MMPA authorization for the MITT
Study Area, which expires on August 3, 2020.
Description of the Specified Activity
The Navy requests authorization to take marine mammals incidental
to conducting training and testing activities. The Navy has determined
that acoustic and explosive stressors are most likely to result in
impacts on marine mammals that could rise to the level of harassment,
and NMFS concurs with this determination. Detailed descriptions of
these activities are provided in Chapter 2 of the 2019 MITT Draft
Supplemental Environmental Impact Statement (SEIS)/Overseas EIS (OEIS)
(MITT DSEIS/OEIS) and in the Navy's rule making/LOA application
(https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities) and are
summarized here.
Dates and Duration
The specified activities would occur at any time during the seven-
year period of validity of the regulations. The proposed number of
training and testing activities are described in the Detailed
Description of the Specified Activities section (Tables 1 through 5).
Geographical Region
The MITT Study Area is comprised of three components: (1) The MIRC,
(2) additional areas on the high seas, and (3) a transit corridor
between the MIRC and the HRC as depicted in Figure 1 below. The MIRC
includes the waters south of Guam to north of Pagan (CNMI), and from
the Pacific Ocean east of the Mariana Islands to the Philippine Sea to
the west, encompassing 501,873 square nautical miles (NM\2\) of open
ocean (Figure 1). For the additional areas of the high seas, this
includes the area to the north of the MIRC that is within the U.S.
Exclusive Economic Zone (EEZ) of the CNMI and the areas to the west of
the MIRC. The transit corridor is outside the geographic boundaries of
the MIRC and represents a great circle route (i.e., the shortest
distance) across the high seas for Navy ships transiting between the
MIRC and the HRC. Although not part of any defined range complex, the
transit corridor is important to the Navy in that it provides available
air, sea, and undersea space where vessels and aircraft conduct
training and testing while in transit. While in transit and along the
corridor, vessels and aircraft would, at times, conduct basic and
routine unit-level activities such as gunnery and sonar training. Ships
also conduct sonar maintenance, which includes active sonar
transmissions.
BILLING CODE 3510-22-P
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BILLING CODE 3510-22-C
Training and testing activities occur within the MITT Study Area,
which is composed of a designated set of specifically bounded
geographic areas encompassing a water component (above and below the
surface), airspace, and for training a land component, such as Farallon
de Medinilla (FDM). The MIRC includes established OPAREAs and special
use airspace, which may be further divided to provide safety and better
control of the area and activities being conducted.
The MIRC includes approximately 40,000 NM \2\ of special use
airspace. This airspace is almost entirely over the ocean (except W13A)
and includes warning areas, and restricted areas (R) (see the MITT
Draft SEIS/OEIS, Figure 2.1-2 and Figure 2.1-3, for details). Warning
Areas (W)-517 and W-12 include approximately 11,800 NM\2\ of special
use airspace; W-11 (A/B) is approximately 10,500 NM\2\ of special use
airspace, and W-13 (A/B/C) is approximately 18,000 NM\2\ of special use
airspace. The restricted area airspace over or near land areas within
the MIRC includes approximately 2,463 NM\2\ of special use airspace and
restricted areas (R) 7201 and R7201A, which extends in a 12 NM radius
around FDM.
The MIRC includes the sea and undersea space from the ocean surface
to the ocean floor. The MIRC also consists of designated sea and
undersea space training areas, which include designated drop zones;
underwater demolition and floating mine exclusion zones; danger zones
associated with live-fire ranges; and training areas associated with
military controlled beaches, harbors, and littoral areas.
Additionally, the MITT Study Area includes pierside locations in
the Apra Harbor Naval Complex where surface ship and submarine sonar
maintenance and testing occur. Activities in Apra Harbor include
channels and routes to and from the Navy port in the Apra Harbor Naval
Complex, and associated wharves and facilities within the Navy port.
Primary Mission Areas
The Navy categorizes its at-sea activities into functional warfare
areas called primary mission areas. These activities generally fall
into the following eight primary mission areas: Air warfare; amphibious
warfare; anti-submarine warfare (ASW); electronic warfare;
expeditionary warfare; mine warfare (MIW); strike warfare; and surface
warfare (SUW). Most activities
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addressed in the MITT Study Area are categorized under one of the
primary mission areas. Activities that do not fall within one of these
areas are listed as ``other activities.'' Each warfare community
(surface, subsurface, aviation, and expeditionary warfare) may train in
some or all of these primary mission areas. The testing community also
categorizes most, but not all, of its testing activities under these
primary mission areas. A description of the sonar, munitions, targets,
systems, and other material used during training and testing activities
within these primary mission areas is provided in the 2019 MITT DSEIS/
OEIS Appendix A (Training and Testing Activities Descriptions).
The Navy describes and analyzes the effects of its activities
within the 2019 MITT DSEIS/OEIS (U.S. Department of the Navy, 2019). In
its assessment, the Navy concluded that sonar and other transducers and
in-water detonations were the stressors that would result in impacts on
marine mammals that could rise to the level of harassment as defined
under the MMPA. Therefore, the Navy's rulemaking/LOA application
provides the Navy's assessment of potential effects from these
stressors in terms of the various warfare mission areas in which they
would be conducted. Those mission areas include the following:
[ssquf] Amphibious warfare (underwater detonations)
[ssquf] ASW (sonar and other transducers, underwater detonations)
[ssquf] MIW (sonar and other transducers, underwater detonations)
[ssquf] SUW (underwater detonations)
[ssquf] Other training and testing activities (sonar and other
transducers)
The Navy's training and testing activities in air warfare,
electronic warfare, and expeditionary warfare do not involve sonar and
other transducers, underwater detonations, or any other stressors that
could result in harassment, serious injury, or mortality of marine
mammals. Therefore, the activities in air, electronic, and
expeditionary warfare areas are not discussed further in this proposed
rule, but are analyzed fully in the Navy's 2019 MITT DSEIS/OEIS.
Amphibious Warfare
The mission of amphibious warfare is to project military power from
the sea to the shore (i.e., attack a threat on land by a military force
embarked on ships) through the use of naval firepower and expeditionary
landing forces. Amphibious warfare operations range from small unit
reconnaissance or raid missions to large-scale amphibious exercises
involving multiple ships and aircraft combined into a strike group.
Amphibious warfare training spans from individual, crew, and small
unit events to large task force exercises. Individual and crew training
include amphibious vehicles and naval gunfire support training. Such
training includes shore assaults, boat raids, airfield or port
seizures, and reconnaissance. Large-scale amphibious exercises involve
ship-to-shore maneuver, naval fire support, such as shore bombardment,
and air strike and attacks on targets that are in close proximity to
friendly forces.
Testing of guns, munitions, aircraft, ships, and amphibious vessels
and vehicles used in amphibious warfare are often integrated into
training activities and, in most cases, the systems are used in the
same manner in which they are used for training activities. Amphibious
warfare tests, when integrated with training activities or conducted
separately as full operational evaluations on existing amphibious
vessels and vehicles following maintenance, repair, or modernization,
may be conducted independently or in conjunction with other amphibious
ship and aircraft activities. Testing is performed to ensure effective
ship-to-shore coordination and transport of personnel, equipment, and
supplies. Tests may also be conducted periodically on other systems,
vessels, and aircraft intended for amphibious operations to assess
operability and to investigate efficacy of new technologies.
ASW
The mission of anti-submarine warfare is to locate, neutralize, and
defeat hostile submarine forces that threaten Navy surface forces.
Anti-submarine warfare can involve various assets such as aircraft,
ships, and submarines, which all search for hostile submarines. These
forces operate together or independently to gain early warning and
detection, and to localize, track, target, and attack submarine
threats.
Anti-submarine warfare training addresses basic skills such as
detecting and classifying submarines, as well as evaluating sounds to
distinguish between enemy submarines and friendly submarines, ships,
and marine life. More advanced training integrates the full spectrum of
anti-submarine warfare from detecting and tracking a submarine to
attacking a target using either exercise torpedoes (i.e., torpedoes
that do not contain an explosive warhead) or simulated weapons. These
integrated anti-submarine warfare training exercises are conducted in
coordinated, at-sea training events involving submarines, ships, and
aircraft.
Testing of anti-submarine warfare systems is conducted to develop
new technologies and assess weapon performance and operability with new
systems and platforms, such as unmanned systems. Testing uses ships,
submarines, and aircraft to demonstrate capabilities of torpedoes,
missiles, countermeasure systems, and underwater surveillance and
communications systems. Tests may be conducted as part of a large-scale
training event involving submarines, ships, fixed-wing aircraft, and
helicopters. These integrated training events offer opportunities to
conduct research and acquisition activities and to train personnel in
the use of new or newly enhanced systems during a large scale, complex
exercise.
MIW
The mission of mine warfare is to detect, classify, and avoid or
neutralize (disable) mines to protect Navy ships and submarines and to
maintain free access to ports and shipping lanes. Mine warfare also
includes training and testing in offensive mine laying. Naval mines can
be laid by ships, submarines, or aircraft.
Mine warfare training includes exercises in which ships, aircraft,
submarines, underwater vehicles, unmanned vehicles, or marine mammal
detection systems search for mine shapes. Personnel train to destroy or
disable mines by attaching underwater explosives to or near the mine or
using remotely operated vehicles to destroy the mine. Towed influence
mine sweep systems mimic a particular ship's magnetic and acoustic
signature, which would trigger a real mine causing it to explode.
Testing and development of mine warfare systems is conducted to
improve sonar, laser, and magnetic detectors intended to hunt, locate,
and record the positions of mines for avoidance or subsequent
neutralization. Mine warfare testing and development fall into two
primary categories: Mine detection and classification, and mine
countermeasure and neutralization testing. Mine detection and
classification testing involves the use of air, surface, and subsurface
vessels and uses sonar, including towed and side scan sonar, and
unmanned vehicles to locate and identify objects underwater. Mine
detection and classification systems are sometimes used in conjunction
with a mine neutralization system. Mine countermeasure and
neutralization testing includes the use
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of air, surface, and subsurface units and uses tracking devices and
countermeasure and neutralization systems to evaluate the effectiveness
of neutralizing mine threats. Most neutralization tests use mine
shapes, or non-explosive practice mines, to accomplish the requirements
of the activity. For example, during a mine neutralization test, a
previously located mine is destroyed or rendered nonfunctional using a
helicopter or manned/unmanned surface vehicle-based system that may
involve the deployment of a towed neutralization system.
Most training and testing activities use mine shapes, or non-
explosive practice mines, to accomplish the requirements of the
activity. A small percentage of mine warfare activities require the use
of high-explosive mines to evaluate and confirm the ability of the
system or the crews conducting the training to neutralize a high-
explosive mine under operational conditions. The majority of mine
warfare systems are deployed by ships, helicopters, and unmanned
vehicles. Tests may also be conducted in support of scientific research
to support these new technologies.
SUW
The mission of surface warfare is to obtain control of sea space
from which naval forces may operate, which entails offensive action
against surface targets while also defending against aggressive actions
by enemy forces. In the conduct of surface warfare, aircraft use guns,
air-launched cruise missiles, or other precision-guided munitions;
ships employ naval guns and surface-to-surface missiles; and submarines
attack surface ships using torpedoes or submarine-launched, anti-ship
cruise missiles.
Surface warfare training includes surface-to-surface gunnery and
missile exercises, air-to-surface gunnery and missile exercises,
submarine missile or torpedo launch activities, and other munitions
against surface targets.
Testing of weapons used in surface warfare is conducted to develop
new technologies and to assess weapon performance and operability with
new systems and platforms, such as unmanned systems. Tests include
various air-to-surface guns and missiles, surface-to-surface guns and
missiles, and bombing tests. Testing activities may be integrated into
training activities to test aircraft or aircraft systems in the
delivery of munitions on a surface target. In most cases the tested
systems are used in the same manner in which they are used for training
activities.
Other Activities
Naval forces conduct additional training, testing and maintenance
activities that do not fit into the primary mission areas that are
listed above. The 2019 MITT DSEIS/OEIS combines these training and
testing activities together in an ``other activities'' grouping for
simplicity. These training and testing activities include, but are not
limited to, sonar maintenance for ships and submarines, submarine
navigation, and acoustic and oceanographic research. These activities
include the use of various sonar systems.
Overview of Major Training Activities and Exercises Within the MITT
Study Area
A major training exercise (MTE) for purposes of this rulemaking is
comprised of several unit-level activities conducted by several units
operating together, commanded and controlled by a single Commander, and
typically generating more than 100 hours of active sonar. These
exercises typically employ an exercise scenario developed to train and
evaluate the exercise participants in tactical and operational tasks.
In an MTE, most of the activities being directed and coordinated by the
Commander in charge of the exercise are identical in nature to the
activities conducted during individual, crew, and smaller unit-level
training events. In an MTE, however, these disparate training tasks are
conducted in concert, rather than in isolation.
Exercises may also be categorized as integrated or coordinated ASW
exercises. The distinction between integrated and coordinated ASW
exercises is how the units are being controlled. Integrated ASW
exercises are controlled by an existing command structure, and
generally occur during the Integrated Phase of the training cycle.
Coordinated exercises may have a command structure stood up solely for
the event; for example, the commanding officer of a ship may be placed
in tactical command of other ships for the duration of the exercise.
Not all integrated ASW exercises are considered MTEs, due to their
scale, number of participants, duration, and amount of active sonar.
The distinction between large, medium, and small integrated or
coordinated exercises is based on the scale of the exercise (i.e.,
number of ASW units participating), the length of the exercise, and the
total number of active sonar hours. NMFS considered the effects of all
training exercises, not just these major, integrated, and coordinated
training exercises in this proposed rule.
Overview of Testing Activities Within the MITT Study Area
Navy's research and acquisition community engages in a broad
spectrum of testing activities in support of the Fleet. These
activities include, but are not limited to, basic and applied
scientific research and technology development; testing, evaluation,
and maintenance of systems (missiles, radar, and sonar) and platforms
(surface ships, submarines, and aircraft); and acquisition of systems
and platforms. The individual commands within the research and
acquisition community include Naval Air Systems Command, Naval Sea
Systems Command, and Office of Naval Research.
Description of Acoustic and Explosive Stressors
The Navy uses a variety of sensors, platforms, weapons, and other
devices, including ones used to ensure the safety of Sailors and
Marines, to meet its mission. Training and testing with these systems
may introduce acoustic (sound) energy or shock waves from explosives
into the environment. The following subsections describe the acoustic
and explosive stressors for marine mammals and their habitat (including
prey species) within the MITT Study Area. Because of the complexity of
analyzing sound propagation in the ocean environment, the Navy relies
on acoustic models in its environmental analyses and rulemaking/LOA
application that consider sound source characteristics and varying
ocean conditions across the MITT Study Area. Stressor/resource
interactions that were determined to have de minimis or no impacts
(i.e., vessel, aircraft, or weapons noise, and explosions in air) were
not carried forward for analysis in the Navy's rulemaking/LOA
application. NMFS reviewed the Navy's analysis and conclusions on de
minimis sources and finds them complete and supportable.
Acoustic Stressors
Acoustic stressors include acoustic signals emitted into the water
for a specific purpose, such as sonar and other transducers (devices
that convert energy from one form to another--in this case, into sound
waves), as well as incidental sources of broadband sound produced as a
byproduct of vessel movement and use of weapons or other deployed
objects. Explosives also produce broadband sound but are characterized
separately from other acoustic sources due to their unique hazardous
characteristics. Characteristics of each of these sound
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sources are described in the following sections.
In order to better organize and facilitate the analysis of
approximately 300 sources of underwater sound used for training and
testing by the Navy, including sonar and other transducers and
explosives, a series of source classifications, or source bins, was
developed. The source classification bins do not include the broadband
sounds produced incidental to vessel or aircraft transits, weapons
firing, and bow shocks.
The use of source classification bins provides the following
benefits:
[ssquf] Provides the ability for new sensors or munitions to be
covered under existing authorizations, as long as those sources fall
within the parameters of a ``bin;''
[ssquf] Improves efficiency of source utilization data collection
and reporting requirements anticipated under the MMPA authorizations;
[ssquf] Ensures a conservative approach to all impact estimates, as
all sources within a given class are modeled as the most impactful
source (highest source level, longest duty cycle, or largest net
explosive weight) within that bin;
[ssquf] Allows analyses to be conducted in a more efficient manner,
without any compromise of analytical results; and
[ssquf] Provides a framework to support the reallocation of source
usage (hours/explosives) between different source bins, as long as the
total numbers of takes remain within the overall analyzed and
authorized limits. This flexibility is required to support evolving
Navy training and testing requirements, which are linked to real world
events.
Sonar and Other Transducers
Active sonar and other transducers emit non-impulsive sound waves
into the water to detect objects, navigate safely, and communicate.
Passive sonars differ from active sound sources in that they do not
emit acoustic signals; rather, they only receive acoustic information
about the environment, or listen. In this proposed rule, the terms
sonar and other transducers will be used to indicate active sound
sources unless otherwise specified.
The Navy employs a variety of sonars and other transducers to
obtain and transmit information about the undersea environment. Some
examples are mid-frequency hull-mounted sonars used to find and track
enemy submarines; high-frequency small object detection sonars used to
detect mines; high-frequency underwater modems used to transfer data
over short ranges; and extremely high-frequency (greater than 200
kilohertz (kHz)) doppler sonars used for navigation, like those used on
commercial and private vessels. The characteristics of these sonars and
other transducers, such as source level, beam width, directivity, and
frequency, depend on the purpose of the source. Higher frequencies can
carry more information or provide more information about objects off
which they reflect, but attenuate more rapidly. Lower frequencies
attenuate less rapidly, so may detect objects over a longer distance,
but with less detail.
Propagation of sound produced underwater is highly dependent on
environmental characteristics such as bathymetry, bottom type, water
depth, temperature, and salinity. The sound received at a particular
location will be different than near the source due to the interaction
of many factors, including propagation loss; how the sound is
reflected, refracted, or scattered; the potential for reverberation;
and interference due to multi-path propagation. In addition, absorption
greatly affects the distance over which higher-frequency sounds
propagate.
The sound sources and platforms typically used in naval activities
analyzed in the Navy's rulemaking/LOA application are described in
Appendix A (Training and Testing Activities Descriptions) of the 2019
MITT DSEIS/OEIS. The effects of these factors are explained in Appendix
H (Acoustic and Explosive Concepts) of the MITT DEIS/OEIS. Sonars and
other transducers used to obtain and transmit information underwater
during Navy training and testing activities generally fall into several
categories of use described below.
ASW
Sonar used during ASW training and testing would impart the
greatest amount of acoustic energy of any category of sonar and other
transducers analyzed in this proposed rule. Types of sonars used to
detect vessels include hull-mounted, towed, line array, sonobuoy,
helicopter dipping, and torpedo sonars. In addition, acoustic targets
and torpedo countermeasures may be deployed to emulate the sound
signatures of vessels or repeat received signals.
Most ASW sonars are mid-frequency (1-10 kHz) because mid-frequency
sound balances sufficient resolution to identify targets with distance
over which threats can be identified. However, some sources may use
higher or lower frequencies. Duty cycles can vary widely, from rarely
used to continuously active. The beam pattern of ASW sonars can be
wide-ranging in a search mode or highly directional in a track mode.
Most ASW activities involving submarines or submarine targets would
occur in waters greater than 600 feet (ft.) deep due to safety concerns
about running aground at shallower depths. Sonars used for ASW
activities would typically be used beyond 12 NM from shore. Exceptions
include use of dipping sonar by helicopters, maintenance of systems
while in Apra Harbor, and system checks while transiting to or from
Apra Harbor.
Mine Warfare, Small Object Detection and Imaging
Sonars used to locate mines and other small objects, similar to
those used in imaging, are typically high frequency or very high
frequency. Higher frequencies allow for greater resolution and, due to
their greater attenuation, are most effective over shorter distances.
Mine detection sonar can be deployed (towed or vessel hull-mounted) at
variable depths on moving platforms (ships, helicopters, or unmanned
vehicles) to sweep a suspected mined area. Hull-mounted anti-submarine
sonars can also be used in an object detection mode known as
``Kingfisher'' mode. Kingfisher mode on vessels is most likely to be
used when transiting to and from port. Sound sources used for imaging
could be used throughout the MITT Study Area.
Sonars used for imaging are usually used in close proximity to the
area of interest, such as pointing downward near the seafloor.
Mine detection sonar use would be concentrated in areas where
practice mines are deployed, typically in water depths less than 200
ft., and at established training and testing minefields, temporary
minefields close to strategic ports and harbors, or at targets of
opportunity such as navigation buoys.
Navigation and Safety
Similar to commercial and private vessels, Navy vessels employ
navigational acoustic devices including speed logs, Doppler sonars for
ship positioning, and fathometers. These may be in use at any time for
safe vessel operation. These sources are typically highly directional
to obtain specific navigational data.
Communication
Sound sources used to transmit data (such as underwater modems),
provide location (pingers), or send a single brief release signal to
bottom-mounted devices (acoustic release) may be used throughout the
MITT Study Area. These
[[Page 5788]]
sources typically have low duty cycles and are usually only used when
it is desirable to send a detectable acoustic message.
Classification of Sonar and Other Transducers
Sonars and other transducers are grouped into classes that share an
attribute, such as frequency range or purpose of use. As detailed
below, classes are further sorted by bins based on the frequency or
bandwidth; source level; and, when warranted, the application in which
the source would be used. Unless stated otherwise, a reference distance
of 1 meter (m) is used for sonar and other transducers.
[ssquf] Frequency of the non-impulsive acoustic source;
[cir] Low-frequency sources operate below 1 kHz;
[cir] Mid-frequency sources operate at and above 1 kHz, up to and
including 10 kHz;
[cir] High-frequency sources operate above 10 kHz, up to and
including 100 kHz;
[cir] Very high-frequency sources operate above 100 kHz but below
200 kHz;
[ssquf] Sound pressure level of the non-impulsive source;
[cir] Greater than 160 decibels (dB) re 1 micro Pascal ([mu]Pa),
but less than 180 dB re 1 [mu]Pa;
[cir] Equal to 180 dB re 1 [mu]Pa and up to 200 dB re 1 [mu]Pa;
[cir] Greater than 200 dB re 1 [mu]Pa;
[ssquf] Application in which the source would be used;
[cir] Sources with similar functions that have similar
characteristics, such as pulse length (duration of each pulse), beam
pattern, and duty cycle.
The bins used for classifying active sonars and transducers that
are quantitatively analyzed in the MITT Study Area are shown in Table 1
below. While general parameters or source characteristics are shown in
the table, actual source parameters are classified.
Table 1--Sonar and Transducers Quantitatively Analyzed in the MITT Study
Area
------------------------------------------------------------------------
Source class category Bin Description
------------------------------------------------------------------------
Low-Frequency (LF): Sources LF4 LF sources equal to
that produce signals less than LF5 180 dB and up to 200
1 kHz. dB.
LF sources less than
180 dB.
Mid-Frequency (MF): Tactical MF1 Hull-mounted surface
and non-tactical sources that MF1K ship sonars (e.g., AN/
produce signals between 1 and MF3 SQS-53C and AN/SQS-
10 kHz. 60).
Kingfisher mode
associated with MF1
sonars.
Hull-mounted submarine
sonars (e.g., AN/BQQ-
10).
MF4 Helicopter-deployed
dipping sonars (e.g.,
AN/AQS-22).
MF5 Active acoustic
sonobuoys (e.g.,
DICASS).
MF6 Underwater sound
signal devices (e.g.,
MK 84 SUS).
MF9 Sources (equal to 180
dB and up to 200 dB)
not otherwise binned.
MF11 Hull-mounted surface
ship sonars with an
active duty cycle
greater than 80
percent.
MF12 Towed array surface
ship sonars with an
active duty cycle
greater than 80
percent.
High-Frequency (HF): Tactical HF1 Hull-mounted submarine
and non-tactical sources that HF3 sonars (e.g., AN/BQQ-
produce signals between 10 and HF4 10).
100 kHz. Other hull-mounted
submarine sonars
(classified).
Mine detection,
classification, and
neutralization sonar
(e.g., AN/SQS-20).
HF6 Sources (equal to 180
dB and up to 200 dB)
not otherwise binned.
Anti-Submarine Warfare (ASW): ASW1 MF systems operating
Tactical sources (e.g., active ASW2 above 200 dB.
sonobuoys and acoustic ASW3 MF Multistatic Active
countermeasures systems) used ASW4 Coherent sonobuoy
during ASW training and ASW5 (e.g., AN/SSQ-125).
testing activities. MF towed active
acoustic
countermeasure
systems (e.g., AN/SLQ-
25).
MF expendable active
acoustic device
countermeasures
(e.g., MK 3).
MF sonobuoys with high
duty cycles.
Torpedoes (TORP): Active TORP1 Lightweight torpedo
acoustic signals produced by TORP2 (e.g., MK 46, MK 54,
torpedoes. TORP3 or Anti-Torpedo
Torpedo).
Heavyweight torpedo
(e.g., MK 48).
Heavyweight torpedo
(e.g., MK 48).
Forward Looking Sonar (FLS): FLS2 HF sources with short
Forward or upward looking pulse lengths, narrow
object avoidance sonars used beam widths, and
for ship navigation and safety. focused beam
patterns.
Acoustic Modems (M): Sources M3 MF acoustic modems
used to transmit data. (greater than 190
dB).
Synthetic Aperture Sonars SAS2 HF SAS systems.
(SAS): Sonars used to form SAS4 MF to HF broadband
high-resolution images of the mine countermeasure
seafloor. sonar.
------------------------------------------------------------------------
Explosive Stressors
This section describes the characteristics of explosions during
naval training and testing. The activities analyzed in Navy's
rulemaking/LOA application that use explosives are described in
Appendix A (Training and Testing Activities Descriptions) of the 2019
MITT DSEIS/OEIS. Explanations of the terminology and metrics used when
describing explosives in the Navy's rule making/LOA application are
also in Appendix H (Acoustic and Explosive Concepts) of the 2019 MITT
DSEIS/OEIS.
The near-instantaneous rise from ambient to an extremely high peak
pressure is what makes an explosive shock wave potentially damaging.
Farther from an explosive, the peak pressures decay and the explosive
waves propagate as an impulsive, broadband sound. Several parameters
influence the effect of an explosive: The weight of the explosive in
the warhead, the type of explosive material, the boundaries and
characteristics of the propagation medium, and, in water, the
detonation depth and the depth of the receiver (i.e., marine mammal).
The net
[[Page 5789]]
explosive weight, which is the explosive power of a charge expressed as
the equivalent weight of trinitrotoluene (TNT), accounts for the first
two parameters. The effects of these factors are explained in Appendix
H (Acoustic and Explosive Concepts) of the 2019 MITT DSEIS/OEIS.
Explosions in Water
Explosive detonations during training and testing activities are
associated with high-explosive munitions, including, but not limited
to, bombs, missiles, rockets, naval gun shells, torpedoes, mines,
demolition charges, and explosive sonobuoys. Explosive detonations
during training and testing involving the use of high-explosive
munitions (including bombs, missiles, and naval gun shells), could
occur in the air or at the water's surface. Explosive detonations
associated with torpedoes and explosive sonobuoys could occur in the
water column; mines and demolition charges could be detonated in the
water column or on the ocean bottom. Most detonations would occur in
waters greater than 200 ft in depth, and greater than 3 NM from shore,
with the exception of three existing mine warfare areas (Outer Apra
Harbor, Piti, and Agat Bay). Nearshore small explosive charges only
occur at the three mine warfare areas. Piti and Agat Bay, while
nearshore, are in very deep water and used for floating mine
neutralization activities. In order to better organize and facilitate
the analysis of explosives used by the Navy during training and testing
that could detonate in water or at the water surface, explosive
classification bins were developed. The use of explosive classification
bins provides the same benefits as described for acoustic source
classification bins discussed above and in Section 1.4.1 (Acoustic
Stressors) of the Navy's rulemaking/LOA application.
Explosives detonated in water are binned by net explosive weight.
The bins of explosives that are proposed for use in the MITT Study Area
are shown in Table 2 below.
Table 2--Explosives Analyzed in the MITT Study Area
----------------------------------------------------------------------------------------------------------------
Net explosive
Bin weight (lb) Example explosive source Modeled detonation depths (ft)
----------------------------------------------------------------------------------------------------------------
E1........................ 0.1-0.25 Medium-caliber projectiles... 0.3, 60.
E2........................ >0.25-0.5 Anti-swimmer grenade......... 0.3.
E3........................ >0.5-2.5 57 mm projectile............. 0.3, 60.
E4........................ >2.5-5 Mine neutralization charge... 33, 197.
E5........................ >5-10 5 in projectiles............. 0.3, 10, 98.
E6........................ >10-20 Hellfire missile............. 0.3, 98.
E8........................ >60-100 250 lb. bomb; Lightweight 0.3, 150.
torpedo.
E9........................ >100-250 500 lb bomb.................. 0.3.
E10....................... >250-500 1,000 lb bomb................ 0.3.
E11....................... >500-650 Heavyweight torpedo.......... 150, 300.
E12....................... >650-1,000 2,000 lb bomb................ 0.3.
----------------------------------------------------------------------------------------------------------------
Notes: (1) Net Explosive Weight refers to the equivalent amount of TNT. The actual weight of a munition may be
larger due to other components; (2) in = inch(es), lb = pound(s), ft = feet.
Propagation of explosive pressure waves in water is highly
dependent on environmental characteristics such as bathymetry, bottom
type, water depth, temperature, and salinity, which affect how the
pressure waves are reflected, refracted, or scattered; the potential
for reverberation; and interference due to multi-path propagation. In
addition, absorption greatly affects the distance over which higher-
frequency components of explosive broadband noise can propagate.
Appendix H (Acoustic and Explosive Concepts) of the 2019 MITT DSEIS/
OEIS explains the characteristics of explosive detonations and how the
above factors affect the propagation of explosive energy in the water.
Explosive Fragments
Marine mammals could be exposed to fragments from underwater
explosions associated with the specified activities. When explosive
ordnance (e.g., bomb or missile) detonates, fragments of the weapon are
thrown at high-velocity from the detonation point, which can injure or
kill marine mammals if they are struck. These fragments may be of
variable size and are ejected at supersonic speed from the detonation.
The casing fragments will be ejected at velocities much greater than
debris from any target due to the proximity of the casing to the
explosive material. Risk of fragment injury reduces exponentially with
distance as the fragment density is reduced. Fragments underwater tend
to be larger than fragments produced by in-air explosions (Swisdak and
Montaro, 1992). Underwater, the friction of the water would quickly
slow these fragments to a point where they no longer pose a threat.
Opposingly, the blast wave from an explosive detonation moves
efficiently through the seawater. Because the ranges to mortality and
injury due to exposure to the blast wave are likely to far exceed the
zone where fragments could injure or kill an animal, the thresholds for
assessing the likelihood of harassment from a blast, which are also
used to inform mitigation zones, are assumed to encompass risk due to
fragmentation.
Other Stressor--Vessel Strike
NMFS also considered the chance that a vessel utilized in training
or testing activities could strike a marine mammal. Vessel strikes have
the potential to result in incidental take from serious injury and/or
mortality. Vessel strikes are not specific to any particular training
or testing activity, but rather are a limited, sporadic, and incidental
result of Navy vessel movement within a study area. Vessel strikes from
commercial, recreational, and military vessels are known to seriously
injure and occasionally kill cetaceans (Abramson et al., 2011; Berman-
Kowalewski et al., 2010; Calambokidis, 2012; Douglas et al., 2008;
Laggner, 2009; Lammers et al., 2003; Van der Hoop et al., 2012; Van der
Hoop et al., 2013), although reviews of the literature on ship strikes
mainly involve collisions between commercial vessels and whales (Jensen
and Silber, 2003; Laist et al., 2001). Vessel speed, size, and mass are
all important factors in determining both the potential likelihood and
impacts of a vessel strike to marine mammals (Conn and Silber, 2013;
Gende et al., 2011; Silber et al., 2010; Vanderlaan and Taggart, 2007;
Wiley et al., 2016). For large vessels,
[[Page 5790]]
speed and angle of approach can influence the severity of a strike.
Navy vessels transit at speeds that are optimal for fuel
conservation and to meet training and testing requirements. Vessels
used as part of the proposed specified activities include ships,
submarines, unmanned vessels, and boats ranging in size from small, 22
ft (7 m) rigid hull inflatable boats to aircraft carriers with lengths
up to 1,092 ft (333 m). The average speed of large Navy ships ranges
between 10 and 15 knots (kn), and submarines generally operate at
speeds in the range of 8 to 13 kn, while a few specialized vessels can
travel at faster speeds. Small craft (for purposes of this analysis,
less than 18 m in length) have much more variable speeds (0 to 50+ kn,
dependent on the activity), but generally range from 10 to 14 kn. From
unpublished Navy data, average median speed for large Navy ships in the
other Navy ranges from 2011-2015 varied from 5 to 10 kn with variations
by ship class and location (i.e., slower speeds close to the coast).
Similar patterns would occur in the MITT Study Area. A full description
of Navy vessels that are used during training and testing activities
can be found in Chapter 2 (Description of Proposed Action and
Alternatives) of the 2019 MITT DSEIS/OEIS.
While these speeds are representative of most events, some vessels
need to temporarily operate outside of these parameters for certain
times or during certain activities. For example, to produce the
required relative wind speed over the flight deck, an aircraft carrier
engaged in flight operations must adjust its speed through the water
accordingly. Also, there are other instances, such as launch and
recovery of a small rigid hull inflatable boat; vessel boarding,
search, and seizure training events; or retrieval of a target when
vessels would be dead in the water or moving slowly ahead to maintain
steerage.
Large Navy vessels (greater than 18 m in length) within the
offshore areas of range complexes and testing ranges operate
differently from commercial vessels in ways that may reduce potential
whale collisions. Surface ships operated by or for the Navy have
multiple personnel assigned to stand watch at all times, when a ship or
surfaced submarine is moving through the water (underway). A primary
duty of personnel standing watch on surface ships is to detect and
report all objects and disturbances sighted in the water that may
indicate a threat to the vessel and its crew, such as debris, a
periscope, surfaced submarine, or surface disturbance. Per vessel
safety requirements, personnel standing watch also report any marine
mammals sighted in the path of the vessel as a standard collision
avoidance procedure. All vessels proceed at a safe speed so they can
take proper and effective action to avoid a collision with any sighted
object or disturbance, and can be stopped within a distance appropriate
to the prevailing circumstances and conditions.
Detailed Description of the Specified Activities
Proposed Training and Testing Activities
The Navy's Operational Commands and various System Commands have
identified activity levels that are needed in the MITT Study Area to
ensure naval forces have sufficient training, maintenance, and new
technology to meet Navy missions in the Pacific. Training prepares Navy
personnel to be proficient in safely operating and maintaining
equipment, weapons, and systems to conduct assigned missions. Navy
research develops new science and technology followed by concept
testing relevant to future Navy needs. Unlike other Navy range
complexes, training and testing in the MITT Study Area is more episodic
as transiting strike groups or individual units travel through on the
way to and from the Western Pacific, or forward deployed assets
temporarily travel to the MITT Study Area for individual or group
activities. This section analyzes a maximum number of activities that
could occur each year and then a maximum total of activities that could
occur for seven years. One activity, Torpedo (Explosive) Testing, does
not occur every year, but the maximum times it could occur over one
year and seven years was analyzed.
The training and testing activities that the Navy proposes to
conduct in the MITT Study Area are summarized in Table 3. The table is
organized according to primary mission areas and includes the activity
name, associated stressors of Navy's activities, description of the
activity, sound source bin, the locations of those activities in the
MITT Study Area, and the number of Specified Activities. For further
information regarding the primary platform used (e.g., ship or aircraft
type) see Appendix A (Training and Testing Activities Descriptions) of
the 2019 MITT DSEIS/OEIS.
Table 3--Proposed Training and Testing Activities Analyzed for Seven-Year Period in the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Typical duration of Annual # 7-Year #
Stressor category Activity Description event Source bin \1\ Location of events of events
--------------------------------------------------------------------------------------------------------------------------------------------------------
Major Training Event--Large Integrated Anti-Submarine Warfare Training (ASW)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.............. Joint Multi- Typically a 10-day Joint 10 days............. ASW2, ASW3, ASW4, Study Area; MIRC. 1 4
Strike Group exercise, in which up to HF1, MF1, MF11,
Exercise. three carrier strike MF3, MF4, MF5,
groups would conduct MF12, TORP1.
training exercises
simultaneously.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Major Training Event--Medium Integrated ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.............. Joint Typically a 10-day exercise 10 days............. ASW2, ASW3, MF1, Study Area; Apra 1 7
Expeditionary that could include a MF4, MF5, MF12. Harbor.
Exercise. Carrier Strike Group and
Expeditionary Strike
Group, Marine
Expeditionary Units, Army
Infantry Units, and Air
Force aircraft together in
a joint environment that
includes planning and
execution efforts as well
as military training
activities at sea, in the
air, and ashore.
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 5791]]
Medium Coordinated ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.............. Marine Air Ground Typically a 10-day exercise 10 days............. ASW3, MF1, MF4, Study Area to 4 28
Task Force that conducts over the MF12. nearshore; MIRC;
Exercise horizon, ship to objective Tinian; Guam;
(Amphibious)--Ba maneuver for the elements Rota; Saipan;
ttalion. of the Expeditionary FDM.
Strike Group and the
Amphibious Marine Air
Ground Task Force. The
exercise utilizes all
elements of the Marine Air
Ground Task Force
(Amphibious), conducting
training activities ashore
with logistic support of
the Expeditionary Strike
Group and conducting
amphibious landings.
--------------------------------------------------------------------------------------------------------------------------------------------------------
ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.............. Tracking Helicopter crews search 2-4 hours........... MF4, MF5......... Study Area > 3 NM 10 70
Exercise--Helico for, detect, and track from land;
pter (TRACKEX-- submarines. Transit Corridor.
Helo).
Acoustic.............. Torpedo Exercise-- Helicopter crews search 2-5 hours........... MF4, MF5, TORP1.. Study Area > 3 NM 6 42
Helicopter for, detect, and track from land.
(TORPEX--Helo). submarines. Recoverable
air launched torpedoes are
employed against submarine
targets.
Acoustic.............. Tracking Maritime patrol aircraft 2-8 hours........... MF5.............. Study Area > 3 NM 36 252
Exercise--Mariti crews search for, detect, from land.
me Patrol and track submarines.
Aircraft
(TRACKEX--Mariti
me Patrol
Aircraft).
Acoustic.............. Torpedo Exercise-- Maritime patrol aircraft 2-8 hours........... MF5, TORP1....... Study Area > 3 NM 6 42
Maritime Patrol crews search for, detect, from land.
Aircraft and track submarines.
(TORPEX--Maritim Recoverable air launched
e Patrol torpedoes are employed
Aircraft). against submarine targets.
Acoustic.............. Tracking Surface ship crews search 2-4 hours........... ASW1, ASW3, MF1, Study Area > 3 NM 91 637
Exercise--Surfac for, detect, and track MF11, MF12. from land.
e (TRACKEX-- submarines.
Surface).
Acoustic.............. Torpedo Exercise-- Surface ship crews search 2-5 hours........... ASW3, MF1, MF5, Study Area > 3 NM 6 42
Surface (TORPEX-- for, detect, and track TORP1. from land.
Surface). submarines. Exercise
torpedoes are used during
this event.
Acoustic.............. Tracking Submarine crews search for, 8 hours............. ASW4, HF1, HF3, Study Area > 3 NM 4 28
Exercise--Submar detect, and track MF3. from land;
ine (TRACKEX-- submarines. Transit Corridor.
Sub).
Acoustic.............. Torpedo Exercise-- Submarine crews search for, 8 hours............. ASW4, HF1, MF3, Study Area > 3 NM 9 63
Submarine detect, and track TORP2. from land.
(TORPEX--Sub). submarines. Recoverable
exercise torpedoes are
used during this event.
Acoustic.............. Small Joint Typically, a 5-day exercise 5 days.............. ASW2, ASW3, ASW4, Study Area > 3 NM 3 21
Coordinated ASW with multiple ships, HF1, MF1, MF3, from land.
exercise (Multi- aircraft and submarines MF4, MF5, MF11,
Sail/GUAMEX). integrating the use of MF12.
their sensors, including
sonobuoys, to search,
detect, and track threat
submarines.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mine Warfare
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.............. Civilian Port Maritime security personnel Multiple days....... HF4, SAS2........ MIRC, Mariana 1 7
Defense. train to protect civilian littorals, Inner
ports and harbors against and Outer Apra
enemy efforts to interfere Harbor.
with access to those
ports.
[[Page 5792]]
Explosive............. Mine Ship, small boat, and 1-4 hours........... E4............... Study Area, 4 28
Neutralization-- helicopter crews locate Mariana
Remotely and disable mines using littorals, and
Operated Vehicle remotely operated Outer Apra
Sonar (ASQ-235 underwater vehicles Harbor.
[AQS-20], SLQ-
48).
Acoustic.............. Mine Ship crews detect, locate, 1-4 hours........... HF4.............. Study Area, Apra 4 28
Countermeasure identify, and avoid mines Harbor.
Exercise--Surfac while navigating
e Ship Sonar restricted areas or
(SQQ-32, MCM). channels, such as while
entering or leaving port.
Acoustic.............. Mine Surface ship crews detect 1-4 hours........... HF4.............. Study Area, Apra 4 28
Countermeasure and avoid mines while Harbor.
Exercise--Towed navigating restricted
Sonar (AQS-20). areas or channels using
towed active sonar
systems.
Explosive............. Mine Personnel disable threat Up to 4 hours....... E5, E6........... Agat Bay site, 20 140
Neutralization-- mines using explosive Piti, and Outer
Explosive charges. Apra Harbor.
Ordnance
Disposal.
Acoustic.............. Submarine Mine Submarine crews practice Varies.............. HF1.............. Study Area, 1 7
Exercise. detecting mines in a Mariana
designated area. Littorals, Inner/
Outer Apra
Harbor.
Explosive............. Underwater Navy divers conduct various Varies.............. E5, E6........... Agat Bay site, 45 315
Demolition levels of training and Piti, and Outer
Qualification/ certification in placing Apra Harbor.
Certification. underwater demolition
charges.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Surface Warfare (SUW)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Explosive............. Bombing Exercise Fixed-wing aircrews deliver 1 hour.............. E9, E10, E12..... Study Area, 37 259
(Air-to-Surface). bombs against stationary Special Use
surface targets. Airspace.
Explosive............. Gunnery Exercise Fixed-wing and helicopter 1 hour.............. E1, E2........... Study Area > 12 120 840
(GUNEX) (Air-to- aircrews fire medium- NM from land,
Surface)--Medium- caliber guns at surface Special Use
caliber. targets. Airspace.
Explosive............. GUNEX (Surface-to- Small boat crews fire 1 hour.............. E2............... Study Area > 12 20 140
Surface) Boat-- medium-caliber guns at NM from land,
Medium-caliber. surface targets. Special Use
Airspace.
Explosive............. GUNEX (Surface-to- Surface ship crews fire Up to 3 hours....... E5............... Study Area > 12 255 1,785
Surface) Ship-- large-caliber guns at NM from land,
Large-caliber. surface targets. Special Use
Airspace.
Explosive............. GUNEX (Surface-to- Surface ship crews fire 2-3 hours........... E1............... Study Area > 12 234 1,638
Surface) Ship-- medium and small-caliber NM from land,
Small- and guns at surface targets. Special Use
Medium-caliber. Airspace.
Explosive............. Maritime Security Helicopter, surface ship, Up to 3 hours....... E2............... Study Area; MIRC. 40 280
Operations. and small boat crews
conduct a suite of
maritime security
operations at sea, to
include visit, board,
search and seizure,
maritime interdiction
operations, force
protection, and anti-
piracy operations.
Explosive............. Missile Exercise Fixed-wing and helicopter 2 hours............. E6, E8, E10...... Study Area > 12 10 70
(Air-to-Surface) aircrews fire air-to- NM from land,
(MISSILEX [A-S]). surface missiles at Special Use
surface targets. Airspace.
Explosive............. Missile Exercise Helicopter aircrews fire 1 hour.............. E3............... Study Area > 12 110 770
(Air-to- both precision-guided and NM from land,
Surface)--Rocket unguided rockets at Special Use
(MISSILEX [A-S]-- surface targets. Airspace.
Rocket).
Explosive............. Missile Exercise Surface ship crews defend 2-5 hours........... E6, E10.......... Study Area > 50 28 196
(Surface-to- against surface threats NM from land,
Surface) (ships or small boats) and Special Use
(MISSILEX [S-S]). engage them with missiles. Airspace.
[[Page 5793]]
Explosive............. Sinking Exercise. Aircraft, ship, and 4-8 hours, possibly E5, E8, E10, E11, Study Area > 50 1 4
submarine crews over. E12, TORP2. NM from land and
deliberately sink a 1-2 days............ > 1,000 fathoms
seaborne target, usually a depth.
decommissioned ship made
environmentally safe for
sinking according to U.S.
Environmental Protection
Agency standards, with a
variety of ordnance.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Other Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.............. Submarine Submarine crews operate Up to 2 hours....... HF1, MF3......... Study Area, Apra 8 56
Navigation. sonar for navigation and Harbor, and
detection while transiting Mariana
into and out of port littorals.
during reduced visibility.
Acoustic.............. Submarine Sonar Maintenance of submarine Up to 1 hour........ MF3.............. Study Area; Apra 86 602
Maintenance. sonar and other system Harbor and
checks are conducted Mariana
pierside or at sea. littorals.
Acoustic.............. Surface Ship Maintenance of surface ship Up to 4 hours....... MF1.............. Study Area; Apra 44 308
Sonar sonar and other system Harbor and
Maintenance. checks are conducted Mariana
pierside or at sea. littorals.
Acoustic.............. Unmanned Units conduct training with Up to 24 hours...... FLS2, M3, SAS2, MIRC; Apra Harbor 64 448
Underwater unmanned underwater SAS4. and Mariana
Vehicle Training. vehicles from a variety of littorals.
platforms, including
surface ships, small
boats, and submarines.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Testing Activities--ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic; Explosive... Anti-Submarine The test evaluates the 8 hours............. ASW2, ASW5, E1, Study Area > 3 NM 26 182
Warfare Tracking sensors and systems used E3, MF5, MF6. from land.
Test--Maritime by maritime patrol
Patrol Aircraft aircraft to detect and
(Sonobuoys). track submarines and to
ensure that aircraft
systems used to deploy the
tracking systems perform
to specifications and meet
operational requirements.
Acoustic.............. Anti-Submarine This event is similar to 2-6 flight hours.... MF5, TORP1....... Study Area > 3 NM 20 140
Warfare Torpedo the training event torpedo from land.
Test. exercise. Test evaluates
anti-submarine warfare
systems onboard rotary-
wing and fixed-wing
aircraft and the ability
to search for, detect,
classify, localize, track,
and attack a submarine or
similar target.
Acoustic.............. Anti-Submarine Ships and their supporting 1-2 weeks, with 4-8 ASW1, ASW2, ASW3, Mariana Island 100 700
Warfare Mission platforms (e.g., hours of active ASW5, MF12, MF4, Range Complex.
Package Testing. helicopters and unmanned sonar use with MF5, TORP1.
aerial systems) detect, intervals of non-
localize, and prosecute activity in between.
submarines.
Acoustic.............. At-Sea Sonar At-sea testing to ensure From 4 hours to 11 HF1, HF6, M3, Study Area....... 7 49
Testing. systems are fully days. MF3, MF9.
functional in an open
ocean environment
Acoustic; Explosive... Torpedo Air, surface, or submarine 1-2 days during ASW3, HF1, HF6, Mariana Island 3 9
(Explosive) crews employ explosive and daylight hours. MF1, MF3, MF4, Range Complex.
Testing. non-explosive torpedoes MF5, MF6, TORP1,
against artificial TORP2, E8, E11.
targets.
Acoustic.............. Torpedo (Non- Air, surface, or submarine Up to 2 weeks....... ASW3, ASW4, HF1, Mariana Island 7 49
explosive) crews employ non-explosive HF6, LF4, MF1, Range Complex.
Testing. torpedoes against MF3, MF4, MF5,
submarines or surface MF6, TORP1,
vessels. TORP2, TORP3.
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 5794]]
Mine Warfare
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic; Explosive... Mine Air, surface, and 1-10 days, with HF4, E4.......... MIRC; nearshore 3 21
Countermeasure subsurface vessels intermittent use of and littorals.
and neutralize threat mines countermeasure/
Neutralization and mine-like objects. neutralization
Testing. systems during this
period.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vessel Evaluation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.............. Undersea Warfare Ships demonstrate Up to 10 days....... HF4, MF1, MF4, MIRC............. 1 7
Testing. capability of MF5, TORP1.
countermeasure systems and
underwater surveillance,
weapons engagement, and
communications systems.
This tests ships' ability
to detect, track, and
engage undersea targets.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Additional activities utilizing sources not listed in the Major Training Event and coordinated exercise bins above may occur during these exercises.
All acoustic sources which may be used during training and testing activities have been accounted for in the modeling and analysis presented in this
application and in the 2019 MITT DSEIS/OEIS.
Summary of Acoustic and Explosive Sources Analyzed for Training and
Testing
Tables 4 and 5 show the acoustic and explosive source classes, bins
and quantity used in either hours or counts associated with the Navy's
proposed training and testing activities over a seven-year period in
the MITT Study Area that were analyzed in the Navy's rulemaking/LOA
application. Table 4 describes the acoustic source classes (i.e., low-
frequency (LF), mid-frequency (MF), and high-frequency (HF)) that could
occur over seven years under the proposed training and testing
activities. Acoustic source bin use in the proposed activities would
vary annually. The seven-year totals for the proposed training and
testing activities take into account that annual variability.
Table 4--Acoustic Source Classes Analyzed and Number Used for Seven-Year Period for Training and Testing
Activities in the MITT Study Area
----------------------------------------------------------------------------------------------------------------
7-year
Source class category Bin Description Unit Annual total
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF): Sources that LF4 LF sources equal to H 1 7
produce signals less than 1 kHz. LF5 180 dB and up to 200 H 10 65
dB.
LF sources less than
180 dB.
Mid-Frequency (MF): Tactical and MF1 Hull-mounted surface H 1,818 9,051
non-tactical sources that produce ship sonars (e.g.,
signals between 1 and 10 kHz. AN/SQS-53C and AN/
SQS-60).
MF1K Kingfisher mode H 3 21
associated with MF1
sonars.
MF3 Hull-mounted H 227 1,589
submarine sonars
(e.g., AN/BQQ-10).
MF4 Helicopter-deployed H 185 1,295
dipping sonars
(e.g., AN/AQS-22).
MF5 Active acoustic C 2,094 14,658
sonobuoys (e.g.,
DICASS).
MF6 Active underwater C 74 518
sound signal devices
(e.g., MK 84 SUS).
MF9 Active sources (equal H 29 203
to 180 dB and up to
200 dB) not
otherwise binned.
MF11 Hull-mounted surface H 304 2.128
ship sonars with an
active duty cycle
greater than 80%.
+ MF12 Towed array surface H 616 4,312
ship sonars with an
active duty cycle
greater than 80%.
High-Frequency (HF): Tactical and HF1 Hull-mounted H 73 511
non-tactical sources that produce submarine sonars
signals between 10 and 100 kHz. (e.g., AN/BQQ-10).
HF3 Other hull-mounted H 4 28
submarine sonars
(classified).
HF4 Mine detection, H 1,472 10,304
classification, and
neutralization sonar
(e.g., AN/SQS-20).
HF6 Active sources (equal H 309 2,163
to 180 dB and up to
200 dB) not
otherwise binned.
[[Page 5795]]
Anti-Submarine Warfare (ASW): ASW1 MF systems operating H 192 1,344
Tactical sources (e.g., active ASW2 above 200 dB. C 554 3,808
sonobuoys and acoustic MF Multistatic Active
countermeasures systems) used Coherent sonobuoy
during ASW training and testing (e.g., AN/SSQ-125).
activities.
ASW3 MF towed active H 3,124 21,868
acoustic
countermeasure
systems (e.g., AN/
SLQ-25).
ASW4 MF expendable active C 332 2,324
acoustic device
countermeasures
(e.g., MK 3).
ASW5 MF sonobuoys with H 50 350
high duty cycles.
Torpedoes (TORP): Source classes TORP1 Lightweight torpedo C 71 485
associated with the active (e.g., MK 46, MK 54,
acoustic signals produced by or Anti[dash]Torpedo
torpedoes. Torpedo).
TORP2 Heavyweight torpedo C 62 434
(e.g., MK 48).
TORP3 Heavyweight torpedo C 6 42
test (e.g., MK 48).
Forward Looking Sonar (FLS): FLS2 HF sources with short H 4 28
Forward or upward looking object pulse lengths,
avoidance sonars used for ship narrow beam widths,
navigation and safety. and focused beam
patterns.
Acoustic Modems (M): Systems used M3 MF acoustic modems H 31 217
to transmit data through the water. (greater than 190
dB).
Synthetic Aperture Sonars (SAS): SAS2 HF SAS systems....... H 449 3,143
Sonars in which active acoustic SAS4 MF to HF broadband H 6 42
signals are post-processed to form mine countermeasure
high-resolution images of the sonar.
seafloor.
----------------------------------------------------------------------------------------------------------------
Notes: H= hours; C = count.
Table 5 describes the number of in-water explosives that could be
used in any year under the proposed training and testing activities.
Under the proposed activities bin use would vary annually, and the
seven-year totals for the proposed training and testing activities take
into account that annual variability.
Table 5--Explosive Source Bins Analyzed and Number Used for Seven-Year Period for Training and Testing
Activities Within the MITT Study Area
----------------------------------------------------------------------------------------------------------------
Net explosive Example Modeled detonation
Bin weight (lb) explosive source depths (ft) Annual 7-year total
----------------------------------------------------------------------------------------------------------------
E1................. 0.1-0.25 Medium-caliber 0.3, 60................. 768 5,376
projectiles.
E2................. >0.25-0.5 Anti-swimmer 0.3..................... 400 2,800
grenade.
E3................. >0.5-2.5 57 mm projectile 0.3, 60................. 683 4,591
E4................. >2.5-5 Mine 33, 197................. 44 308
neutralization
charge.
E5................. >5-10 5 in projectiles 0.3, 10, 98............. 1,221 8,547
E6................. >10-20 15 lb shaped 0.3, 98................. 29 203
charge.
E8................. >60-100 250 lb bomb; 0.3, 150................ 134 932
Light weight
torpedo.
E9................. >100-250 500 lb bomb..... 0.3..................... 110 770
E10................ >250-500 1,000 lb bomb... 0.3..................... 78 546
E11................ >500-650 Heavy weight 150,300................. 5 17
torpedo.
E12................ >650-1,000 2,000 lb bomb... 0.3..................... 48 336
----------------------------------------------------------------------------------------------------------------
Notes: (1) net explosive weight refers to the equivalent amount of TNT. The actual weight of a munition may be
larger due to other components. (2) in = inch(es), lb = pound(s), ft = feet.
Vessel Movement
In the MITT Study Area, there is one port on Guam as well as Naval
Base Guam. There are three ports within the CNMI including Port of
Rota, Port of Tinian, and Port of Saipan. However, Navy ships are
mostly associated with transits into and out of Apra Harbor on Guam.
U.S. Navy vessels do not berth at other locations in the MITT Study
Area other than Apra Harbor. Within the CNMI, the Port of Rota (also
called Rota West Harbor) is located on the southwestern tip of the
island. It is a very small, poorly sheltered port with a pierside water
depth of 6 to 10 ft, which limits the size of vessels that can access
the pier. The Port of Rota is mainly used as a port for ferry boats
transporting tourists and residents from its sister island, Tinian. The
Port of Tinian is a well-sheltered small port. Mobile Oil operates a
fuel plant at the port, and a ferry service transports tourists from
Saipan to Tinian. The Port of Saipan is the largest of the three CNMI
ports. The port of Saipan is on the southwest shore and houses
commercial ships, small local boats or ferries, and military vessels
(ships that are not managed by the Navy or part of these proposed
activities). Guam's Jose D. Leon Guerrero Commercial Port is on Cabras
Island along the southwest portion of Guam. The Port Authority of Guam,
administers the Commercial Port, Agana Boat Basin, and the Agat Marina.
While the ships assigned to any particular homeport change
periodically, Naval Base Guam is not home to any surface fleet
commands. There are no Navy surface warships
[[Page 5796]]
homeported in Guam. The types of vessels currently homeported in Apra
Harbor include submarines, support vessels like a submarine tender and
a military sealift (i.e., logistics) unit, and small vessels like
coastal riverine craft. Small vessels stay in nearshore, coastal
waters. Navy large vessel movements for training and testing in the
MITT Study Area often occur when U.S. West Coast and Hawaii based
strike groups or independent deployers (i.e., single vessels) transit
to and from the Western Pacific, Indian Ocean, and Arabian Gulf. The
Navy also maintains a contingent of vessels homeported in Japan that
also visit the MITT Study Area to participate in various single unit or
multi-unit training activities and MTEs. Unlike other Navy range
complexes associated with fleet concentration areas, there may be long
periods, from multiple weeks up to a month or more (e.g., 1-3 months),
without any significant Navy large surface vessel presence in the MITT
Study Area. These gaps are the result of Navy ships training in other
range complexes as part of pre-deployment preparations and Japan-based
ships deployed to other portions of the Western Pacific for operational
reasons.
The western approaches to Apra Harbor are the central corridor of
vessel movements in the MITT Study Area, as visiting, transiting, and
homeported vessels pull in and out for port calls and resupply.
Depending on a given exercise, many of the participating ships could
use Apra Harbor prior to or after the event depending on operational
schedules. A significant amount of MIW events with vessel movements
would be more likely west of Guam and adjacent to Apra Harbor,
depending on the event.
The majority of the Air Warfare (launches from aircraft carriers
and surface ships), ASW, Electronic Warfare, Strike Warfare, and SUW
training and testing events involving vessel movement (Table 6 below)
occurs in or adjacent to the specified training and testing areas shown
in Figure 2-2 of the Navy's rulemaking/LOA application. Vessels
involved in ASW training and testing typically use water depths greater
than 200 m and areas greater than 3 NM from shore, conducting most
events in designated areas or other locations well offshore. For safety
reasons, the Navy also does not conduct explosive events such as vessel
gunnery exercises less than 12 NM from shore, and more often in
designated areas further offshore.
These generalities do not preclude individual ships or strike
groups from conducting select training and testing between designated
Navy training and testing areas, nor does it preclude select training
or testing west of Guam in the eastern and central Philippine Sea or in
the transit lane between Hawaii and the MITT Study Area. While the vast
majority of activities are scheduled in designated areas, operational
schedules could necessitate training or testing in other at-sea
portions of the MITT Study Area and commanders are always able to
conduct unit-level or small group training and testing as opportunities
arise and schedules allow.
Destroyers and cruisers would be the only surface ships conducting
Naval Surface Fire Support Exercise (FIREX)--Land-based target (Land)
and would transit the waters adjacent to FDM, though the duration of
these single events is relatively short (4-6 hours). The ships, because
of both ship draft and training requirements, are typically a mile or
more offshore in deeper waters during execution of FIREX events.
Because of constricted scheduling needs at FDM for both surface and
aviation activities, ships conducting FIREX move into the desired
range, fire off an allotted amount of ordnance (inert or explosive
five-inch projectiles), and depart back to other areas within the MITT
Study Area.
Amphibious Warfare activities have slightly different vessel
movements than activities in other warfare areas. Amphibious MTEs
(Joint Expeditionary Exercise, Marine Air Ground Task Force Exercise
(Amphibious)--Battalion) and other Amphibious Warfare activities
involve amphibious assault ships maneuvering offshore then approaching
designated beach landing areas to offload marines in landing craft,
amphibious assault vehicles, or helicopters. Typical landing locations
depending on activity type include Guam, FDM, Rota, Saipan, and Tinian
(Tinian Military Lease Area). For large surface vessels during
amphibious warfare activities, the objective is to not approach too
close to shore, which would put a ship at risk from shore-based
defenses. Typically, amphibious transport ships deploy landing craft,
amphibious assault vehicles, or helicopters from several miles
offshore. Given the steep nearshore bathymetry in the Mariana Islands
greater than 3NM from shore, these ships are still in significantly
deep water while deploying units (>200 m).
The only areas with consistently high concentrations of Navy vessel
movement would be within Apra Harbor Guam and the coastal approaches to
and from Apra Harbor. Some amphibious events use Tinian as a landing
area so amphibious ships could occur in the offshore waters off that
island. Most other activities are spread throughout the greater MITT
Study Area with a high degree of spatial and temporal separation
between activities.
The Navy tabulated annual at-sea vessel steaming days proposed for
the MITT Study Area. Across all warfare areas and activities, 493 days
of Navy at-sea time would occur annually in the MITT Study Area (Table
6). Amphibious Warfare activities account for 48 percent of total
surface ship days, MTEs account for 38 percent, ASW activities account
for 8 percent, and Air Warfare, ASW and Other activities (sonar
maintenance, anchoring) account for 2 percent each (Table 6). In
comparison to the Hawaii-Southern California Training and Testing
(HSTT) Study Area, the estimated number of at-sea annual days in the
MITT Study Area is approximately ten times less than in the HSTT Study
Area over the same time period.
Table 6--Annual Navy Surface Ship Days Within the MITT Study Area
----------------------------------------------------------------------------------------------------------------
Annual days
MITT events Annual days Percent by by warfare Percent by
event area warfare area
----------------------------------------------------------------------------------------------------------------
AIR WARFARE..................................... .............. .............. 9 1.9
GUNNEX (Lg)................................. 2 0.3 .............. ..............
GUNNEX (Sm)................................. 3 0.6 .............. ..............
MISSILEX.................................... 5 0.9 .............. ..............
AMPHIBIOUS WARFARE.............................. .............. .............. 299 60.7
Fire Support (Land Target).................. 5 1.0 .............. ..............
Amphibious Rehearsal........................ 144 29.2 .............. ..............
Amphibious Assault.......................... 14 2.8 .............. ..............
[[Page 5797]]
Amphibious Raid............................. 3 0.6 .............. ..............
Marine Air Ground Task Force Exercise....... 40 8.1 .............. ..............
Non-Combatant Evacuation Op................. 67 13.5 .............. ..............
Humanitarian Assist/Disaster Relief Op...... 7 1.4 .............. ..............
Special Purpose Marine Air Ground Task Force 20 4.1 .............. ..............
Exercise...................................
SURFACE WARFARE................................. .............. .............. 41 8.4
MISSILEX.................................... 2 0.4 .............. ..............
GUNNEX (Lg)................................. 14 2.8 .............. ..............
GUNNEX (Med)................................ 10 2.0 .............. ..............
GUNNEX (Sm)................................. 6 1.3 .............. ..............
SINKEX...................................... 7 1.4 .............. ..............
Maritime Security Op........................ 3 0.5 .............. ..............
ANTI-SUBMARINE WARFARE.......................... .............. .............. 8 1.6
Tracking Exercise........................... 8 1.5 .............. ..............
Torpedo Exercise............................ 1 0.1 .............. ..............
MAJOR TRAINING EXERCISES........................ .............. .............. 125 24.5
Joint Expeditionary Exercise................ 63 12.9 .............. ..............
Joint Multi-Strike Group Exercise........... 62 12.5 .............. ..............
OTHER........................................... .............. .............. 10 2.1
Surface Ship Sonar Maintenance.............. 7 1.5% .............. ..............
Precision Anchoring......................... 3 0.6% .............. ..............
---------------------------------------------------------------
Total................................... 493 .............. .............. ..............
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
Additional details on Navy at-sea vessel movement are provided in
the 2019 MITT DSEIS/OEIS.
Standard Operating Procedures
For training and testing to be effective, personnel must be able to
safely use their sensors and weapon systems as they are intended to be
used in military missions and combat operations and to their optimum
capabilities. While standard operating procedures are designed for the
safety of personnel and equipment and to ensure the success of training
and testing activities, their implementation often yields additional
benefits on environmental, socioeconomic, public health and safety, and
cultural resources.
Navy standard operating procedures have been developed and refined
over years of experience and are broadcast via numerous naval
instructions and manuals, including, but not limited to:
[ssquf] Ship, submarine, and aircraft safety manuals;
[ssquf] Ship, submarine, and aircraft standard operating manuals;
[ssquf] Fleet Area Control and Surveillance Facility range
operating instructions;
[ssquf] Fleet exercise publications and instructions;
[ssquf] Naval Sea Systems Command test range safety and standard
operating instructions;
[ssquf] Navy instrumented range operating procedures;
[ssquf] Naval shipyard sea trial agendas;
[ssquf] Research, development, test, and evaluation plans;
[ssquf] Naval gunfire safety instructions;
[ssquf] Navy planned maintenance system instructions and
requirements;
[ssquf] Federal Aviation Administration regulations; and
[ssquf] International Regulations for Preventing Collisions at Sea.
Because standard operating procedures are essential to safety and
mission success, the Navy considers them to be part of the proposed
Specified Activities, and has included them in the environmental
analysis. Standard operating procedures that are recognized as
providing a potential benefit to marine mammals during training and
testing activities are noted below and discussed in more detail within
the 2019 MITT DSEIS/OEIS.
[ssquf] Vessel Safety
[ssquf] Weapons Firing Safety
[ssquf] Target Deployment and Retrieval Safety
[ssquf] Towed In-Water Device Procedures
Standard operating procedures (which are implemented regardless of
their secondary benefits) are different from mitigation measures (which
are designed entirely for the purpose of avoiding or reducing potential
impacts on the environment). Refer to Section 2.3.3 Standing Operating
Procedures of the 2019 MITT DSEIS/OEIS for greater detail.
Description of Marine Mammals and Their Habitat in the Area of the
Specified Activities
Marine mammal species that have the potential to occur in the MITT
Study Area are presented in Table 7. The Navy requests authorization to
take individuals of 26 marine mammal species by Level A and Level B
harassment incidental to training and testing activities from the use
of sonar and other transducers, and in-water detonations. The Navy does
not request authorization for any serious injuries or mortalities of
marine mammals, and NMFS agrees that serious injury and mortality is
unlikely to occur from the Navy's activities. There are no areas of
critical habitat designated under the Endangered Species Act (ESA),
Biologically Important Areas, National Marine Sanctuaries, or unusual
mortality events for marine mammals in the MITT Study Area. However,
there are areas known to be important for humpback whale breeding and
calving, which are described below.
Information on the status, distribution, abundance, population
trends, habitat, and ecology of marine mammals in the MITT Study Area
may be found in Chapter 4 of the Navy's rulemaking/LOA application.
NMFS has reviewed this information and found it to be accurate and
complete. Additional information on the general biology and ecology of
marine mammals are included in the 2019 MITT DSEIS/OEIS. There are only
a few species for which
[[Page 5798]]
stock information exists for the MITT Study Area. Table 7 incorporates
data from the U.S. Pacific and the Alaska Marine Mammal Stock
Assessments (Carretta et al., 2017c; Muto et al., 2017b); as well as
incorporates the best available science, including monitoring data from
the Navy's marine mammal research efforts.
Table 7--Marine Mammal Occurrence Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Status Occurrence *
Common name Scientific name ----------------------------------------------------------------------------------------------
MMPA ESA Mariana Islands Transit corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mysticetes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale........................ Balaenoptera musculus D..................... E..................... Seasonal.............. Seasonal.
Bryde's whale..................... Balaenoptera edeni... ...................... n/a................... Regular............... Regular.
Fin whale......................... Balaenoptera physalus D..................... E..................... Rare.................. Rare.
Humpback whale.................... Megaptera (\1\)................. E..................... Seasonal.............. Seasonal.
novaeangliae.
Minke whale....................... Balaenoptera ...................... n/a................... Seasonal.............. Seasonal.
acutorostrata.
Omura's whale..................... Balaenoptera omurai.. ...................... n/a................... Rare.................. Rare.
Sei whale......................... Balaenoptera borealis D..................... E..................... Seasonal.............. Seasonal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontocetes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blainville's beaked whale......... Mesoplodon ...................... n/a................... Regular............... Regular
densirostris.
Common bottlenose dolphin......... Tursiops truncatus... ...................... n/a................... Regular............... Regular.
Cuvier's beaked whale............. Ziphius cavirostris.. ...................... n/a................... Regular............... Regular.
Dwarf sperm whale................. Kogia sima........... ...................... n/a................... Regular............... Regular.
False killer whale................ Pseudorca crassidens. ...................... n/a................... Regular............... Regular.
Fraser's dolphin.................. Lagenodelphis hosei.. ...................... n/a................... Regular............... Regular.
Ginkgo-toothed beaked whale....... Mesoplodon ginkgodens ...................... n/a................... Regular............... Regular.
Killer whale...................... Orcinus orca......... ...................... n/a................... Regular............... Regular.
Longman's beaked whale............ Indopacetus pacificus ...................... n/a................... Regular............... Regular.
Melon-headed whale................ Peponocephala electra ...................... n/a................... Regular............... Regular.
Pantropical spotted dolphin....... Stenella attenuata... ...................... n/a................... Regular............... Regular.
Pygmy killer whale................ Feresa attenuata..... ...................... n/a................... Regular............... Regular.
Pygmy sperm whale................. Kogia breviceps...... ...................... n/a................... Regular............... Regular.
Risso's dolphin................... Grampus griseus...... ...................... n/a................... Regular............... Regular.
Rough-toothed dolphin............. Steno bredanensis.... ...................... n/a................... Regular............... Regular.
Short-finned pilot whale.......... Globicephala ...................... n/a................... Regular............... Regular.
macrorhynchus.
Sperm whale....................... Physeter D..................... E..................... Regular............... Regular.
macrocephalus.
Spinner dolphin................... Stenella longirostris ...................... n/a................... Regular............... Regular.
Striped dolphin................... Stenella coeruleoalba ...................... n/a................... Regular............... Regular.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Humpback whales in the Mariana Islands have not been assigned a stock by NMFS in the Alaska or Pacific Stock Assessment Reports given they are not
recognized in those reports as being present in U.S. territorial waters (Carretta et al., 2017c; Carretta et al., 2018; Muto et al., 2017b; Muto et
al., 2018), but because individuals from the Western North Pacific Distinct Population Segment have been photographically identified in the MITT Study
Area, humpback whales in the Mariana Islands are assumed to be part of the Western North Pacific Stock.
Note: Status MMPA, D = depleted; ESA, E = endangered.
* Species occur in both the Mariana Islands and in the Transit Corridor, both of which are included in the overall MITT Study Area. The transit corridor
is outside the geographic boundaries of the MIRC, but is a route across the high seas for Navy ships transiting between the MIRC and the HRC. Although
not part of a defined range complex, vessels and aircraft would at times conduct basic and routine unit-level activities such as gunnery and sonar
training while in transit in the corridor as long as the training would not interfere with the primary objective of reaching their intended
destination. Ships also conduct sonar maintenance, which includes active sonar transmissions.
Humpback Whale Breeding and Calving Areas
Humpback whale breeding and calving have been documented in the
MITT Study Area and particularly in the shallow waters (mostly within
the 200 m isobath) offshore of Saipan at Marpi Reef and Chalan Kanoa
Reef. Based on surveys conducted by NMFS' Pacific Islands Fisheries
Science Center (PIFSC) during the winter months (January to March)
2015-2019, there were 22 encounters with mother/calf pairs with a total
of 14 mother/calf pairs and all calves were considered born within the
current season and one neotate (Hitt et al., in press). Additionally,
competitive groups were observed in 2017 and 2018 (Hill et al., in
press). Additional information from surveys and passive acoustic
hydrophone recordings in the Mariana Islands has confirmed the presence
of mother-calf pairs, non-calf whales, and singing males in the MITT
Study Area (Fulling et al., 2011; Hill et al., 2016a; Hill et al.,
2018; Munger et al., 2014; Munger et al., 2015; Norris et al., 2012;
Oleson and Hill, 2010a; Oleson et al., 2015; U.S. Department of the
Navy, 2007; Uyeyama et al., 2012). Future surveys are needed to
determine the full extent of the humpback whale breeding habitat
through the Mariana Archipelago; however, the available data confirms
the shallow waters surrounding Marpi and Chalan Kanoa reefs are
important to breeding and calving humpback whales.
Species Not Included in the Analysis
Consistent with the analysis provided in the 2015 MITT FEIS/OEIS
and the previous Phase II rulemaking for the MITT Study Area, the
species carried forward for analysis and in the Navy's rulemaking/LOA
application are those likely to be found in the MITT Study Area based
on the most recent sighting, survey, and habitat modeling data
available. The analysis does not include species that may have once
inhabited or transited the area, but have not been sighted in recent
years (e.g., species that no longer occur in the area due to factors
such as 19th-century commercial exploitation). These species include
the North Pacific right whale (Eubalaena japonica), the western
subpopulation of
[[Page 5799]]
gray whale (Eschrichtius robustus), short-beaked common dolphin
(Delphinus delphis), Indo-Pacific bottlenose dolphin (Tursiops
aduncus), northern elephant seal (Mirounga angustirostris), and
Hawaiian monk seal (Monachus schauinslandi). The reasons for not
including each of these species is explained below and NMFS agrees
these species are unlikely to occur in the MITT Study Area. Further
details can be found in the 2015 MITT FEIS/OEIS.
The North Pacific right whale population is very small, likely in
the low hundred (NMFS 2019). Contemporary sightings of North Pacific
right whales have mostly occurred in the central North Pacific and
Bering Sea. Sightings have been reported as far south as central Baja
California in the eastern North Pacific, as far south as Hawaii in the
central North Pacific, and as far north as the sub-Arctic waters of the
Bering Sea and the Sea of Okhotsk in the summer. Migration patterns of
the North Pacific right whale are unknown, although it is thought the
whales spend the summer in far northern feeding grounds and migrate
south to warmer waters, such as southern California, during the winter.
Due to their known homerange it is unlikely that a North Pacific right
whale would occur in the MITT Study Area. North Pacific right whales
have not been previously documented in the MITT Study Area. For the
reasons discussed above, this species is not discussed further.
For the western subpopulation of gray whales there currently are no
data available to suggest that gray whales would transit the MITT Study
Area when migrating from the western to eastern Pacific. There have
only been 13 records of gray whales in Japanese waters since 1990
(Nambu et al., 2010). The Okhotsk Sea and Sakhalin Island are located
far to the north off Russia, and the South China Sea begins
approximately 1,458 NM east of the MITT Study Area. Given what is known
of their present range, nearshore affinity, and extralimital occurrence
in tropical waters, it is highly unlikely that this species would be
present in the MITT Study Area (Reilly et al., 2000; Weller et al.,
2002; Wiles, 2005; Nambu et al., 2010). In addition, no gray whales
have been previously documented in the MITT Study Area. For the reasons
discussed above, this species is not discussed further.
The short-beaked common dolphin is found worldwide in temperate,
tropical, and subtropical seas. The range of this species may extend
entirely across the tropical and temperate north Pacific (Heyning and
Perrin, 1994); however, this species prefers areas with large seasonal
changes in surface temperature and thermocline depth (the point between
warmer surface water and colder water) (Au and Perryman, 1985). They
are one of the most abundant species found in temperate waters off the
U.S. West Coast (Barlow and Forney, 2007). In tropical seas, they are
typically sighted in upwelling-modified waters such as those in the
eastern tropical Pacific (Au and Perryman, 1985; Ballance and Pitman,
1998; Reilly, 1990). The absence of known areas of major upwelling in
the western tropical Pacific suggests that common dolphins are not
found in the MITT Study Area (Hammond et al., 2008). In addition, no
short-beaked common dolphins have been previously documented in the
MITT Study Area. For the reasons discussed above, this species is not
discussed further.
The Indo-Pacific bottlenose dolphin generally occurs over shallow
coastal waters on the continental shelf. Although typically associated
with continental margins, they do occur around oceanic islands;
however, the MITT Study Area is not included in their known geographic
range, and there are no documented sightings there (Hammond et al.,
2008). In addition, no Indo-Pacific bottlenose dolphins have been
previously documented in the MITT Study Area. For the reasons discussed
above, this species is not discussed further.
The likelihood of a Hawaiian monk seal being present in the MITT
Study Area is extremely low. There are no confirmed records of Hawaiian
monk seals in the Micronesia region; although, Reeves et al. (1999) and
Eldredge (1991, 2003) have noted occurrence records for unidentified
seal species in the Marshall and Gilbert Islands. It is possible that
Hawaiian monk seals wander from the Hawaiian Islands to appear at the
Marshall or Gilbert Islands in the Micronesia region (Eldredge, 1991).
However, the Marshall Islands are located approximately 1,180 mi.
(1,900 km) from Guam and the Gilbert Islands are located even farther
to the east. Given the extremely low likelihood of this species
occurring in the MITT Study Area. No Hawaiian monk seals have been
previously documented in the MITT Study Area. For the reasons discussed
above, this species is not discussed further.
Northern elephant seals (Mirounga angustirostris) are common on
island and mainland haul-out sites in Baja California, Mexico north
through central California. Elephant seals spend several months at sea
feeding and travel as far north as the Gulf of Alaska and forage in the
mid-Pacific as far south as approximately 40 degrees north latitude.
Vagrant individuals do sometimes range to the western north Pacific.
The most far-ranging individual appeared on Nijima Island off the
Pacific coast of Japan in 1989 (Kiyota et al., 1992). Although northern
elephant seals may wander great distances, it is very unlikely that
they would travel to Japan and then continue traveling to the MITT
Study Area. No Northern elephant seals have been previously documented
in the MITT Study Area. For the reasons discussed above, this species
is not discussed further.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Current data indicate that not all marine
mammal species have equal hearing capabilities (e.g., Richardson et
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect
this, Southall et al. (2007) recommended that marine mammals be divided
into functional hearing groups based on directly measured or estimated
hearing ranges on the basis of available behavioral response data,
audiograms derived using auditory evoked potential techniques,
anatomical modeling, and other data. Note that no direct measurements
of hearing ability have been successfully completed for mysticetes
(i.e., low-frequency cetaceans). Subsequently, NMFS (2016) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65 dB
threshold from the normalized composite audiograms, with the exception
for lower limits for low-frequency cetaceans where the lower bound was
deemed to be biologically implausible and the lower bound from Southall
et al. (2007) retained. The functional groups and the associated
frequencies are indicated below (note that these frequency ranges
correspond to the range for the composite group, with the entire range
not necessarily reflecting the capabilities of every species within
that group):
[ssquf] Low-frequency cetaceans (mysticetes): Generalized hearing
is estimated to occur between approximately 7 Hz and 35 kHz;
[ssquf] Mid-frequency cetaceans (larger toothed whales, beaked
whales, and most delphinids): Generalized hearing is
[[Page 5800]]
estimated to occur between approximately 150 Hz and 160 kHz;
[ssquf] High-frequency cetaceans (porpoises, river dolphins, and
members of the genera Kogia and Cephalorhynchus; including two members
of the genus Lagenorhynchus, on the basis of recent echolocation data
and genetic data): Generalized hearing is estimated to occur between
approximately 275 Hz and 160 kHz;
[ssquf] Pinnipeds in water; Phocidae (true seals): Generalized
hearing is estimated to occur between approximately 50 Hz to 86 kHz;
and
[ssquf] Pinnipeds in water; Otariidae (eared seals): Generalized
hearing is estimated to occur between 60 Hz and 39 kHz.
The pinniped functional hearing group was modified from Southall et
al. (2007) on the basis of data indicating that phocid species have
consistently demonstrated an extended frequency range of hearing
compared to otariids, especially in the higher frequency range
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt,
2013).
For more details concerning these groups and associated frequency
ranges, please see NMFS (2016) for a review of the available
information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a discussion of the ways that components of
the specified activity may impact marine mammals and their habitat. The
Estimated Take of Marine Mammals section later in this rule includes a
quantitative analysis of the number of instances of take that could
occur from these activities. The Preliminary Analysis and Negligible
Impact Determination section considers the content of this section, the
Estimated Take of Marine Mammals section, and the Proposed Mitigation
Measures section to draw conclusions regarding the likely impacts of
these activities on the reproductive success or survivorship of
individuals and whether those impacts on individuals are likely to
adversely affect the species through effects on annual rates of
recruitment or survival.
The Navy has requested authorization for the take of marine mammals
that may occur incidental to training and testing activities in the
MITT Study Area. The Navy analyzed potential impacts to marine mammals
from acoustic and explosive sources in its rulemaking/LOA application.
NMFS carefully reviewed the information provided by the Navy along with
independently reviewing applicable scientific research and literature
and other information to evaluate the potential effects of the Navy's
activities on marine mammals, which are presented in this section.
Other potential impacts to marine mammals from training and testing
activities in the MITT Study Area were analyzed in the 2019 MITT DSEIS/
OEIS, in consultation with NMFS as a cooperating agency, and determined
to be unlikely to result in marine mammal take. These include
incidental take from vessel strike and serious injury or mortality from
explosives. Therefore, the Navy has not requested authorization for
take of marine mammals incidental to other components of their proposed
Specified Activities, and we agree that incidental take is unlikely to
occur from those components. In this proposed rule, NMFS analyzes the
potential effects on marine mammals from the activity components that
may cause the take of marine mammals: Exposure to acoustic or explosive
stressors including non-impulsive (sonar and other transducers) and
impulsive (explosives) stressors.
For the purpose of MMPA incidental take authorizations, NMFS'
effects assessments serve four primary purposes: (1) To prescribe the
permissible methods of taking (i.e., Level B harassment (behavioral
harassment and temporary threshold shift (TTS)), Level A harassment
(permanent threshold shift (PTS) and non-auditory injury), serious
injury, or mortality, including identification of the number and types
of take that could occur by harassment, serious injury, or mortality,
and to prescribe other means of effecting the least practicable adverse
impact on the species or stocks and their habitat (i.e., mitigation
measures); (2) to determine whether the specified activities would have
a negligible impact on the affected species or stocks of marine mammals
(based on whether it is likely that the activities would adversely
affect the species or stocks through effects on annual rates of
recruitment or survival); (3) to determine whether the specified
activities would have an unmitigable adverse impact on the availability
of the species or stocks for subsistence uses (however, there are no
subsistence communities that would be affected in the MITT Study Area,
so this determination is inapplicable to this rulemaking); and (4) to
prescribe requirements pertaining to monitoring and reporting.
In this section, NMFS provides a description of the ways marine
mammals may be generally affected by these activities in the form of
mortality, physical trauma, sensory impairment (permanent and temporary
threshold shifts and acoustic masking), physiological responses
(particular stress responses), behavioral disturbance, or habitat
effects. Explosives, which have the potential to result in incidental
take from serious injury and/or mortality, will be discussed in more
detail in the Estimated Take of Marine Mammals section. The Estimated
Take of Marine Mammals section also discusses how the potential effects
on marine mammals from non-impulsive and impulsive sources relate to
the MMPA definitions of Level A and Level B Harassment, and quantifies
those effects that rise to the level of a take. The Preliminary
Analysis and Negligible Impact Determination section assesses whether
the proposed authorized take would have a negligible impact on the
affected species.
Potential Effects of Underwater Sound
Anthropogenic sounds cover a broad range of frequencies and sound
levels and can have a range of highly variable impacts on marine life,
from none or minor to potentially severe responses, depending on
received levels, duration of exposure, behavioral context, and various
other factors. The potential effects of underwater sound from active
acoustic sources can possibly result in one or more of the following:
Temporary or permanent hearing impairment, non-auditory physical or
physiological effects, behavioral disturbance, stress, and masking
(Richardson et al., 1995; Gordon et al., 2004; Nowacek et al., 2007;
Southall et al., 2007; G[ouml]tz et al., 2009, Southall et al., 2019a).
The degree of effect is intrinsically related to the signal
characteristics, received level, distance from the source, and duration
of the sound exposure. In general, sudden, high level sounds can cause
hearing loss, as can longer exposures to lower level sounds. Temporary
or permanent loss of hearing will occur almost exclusively for noise
within an animal's hearing range. Note that, in the following
discussion, we refer in many cases to a review article concerning
studies of noise-induced hearing loss conducted from 1996-2015 (i.e.,
Finneran, 2015). For study-specific citations, please see that work. We
first describe general manifestations of acoustic effects before
providing discussion specific to the Navy's activities.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur, in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First is the area within which the acoustic signal would
[[Page 5801]]
be audible (potentially perceived) to the animal, but not strong enough
to elicit any overt behavioral or physiological response. The next zone
corresponds with the area where the signal is audible to the animal and
of sufficient intensity to elicit behavioral or physiological
responsiveness. Third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory systems. Overlaying these zones
to a certain extent is the area within which masking (i.e., when a
sound interferes with or masks the ability of an animal to detect a
signal of interest that is above the absolute hearing threshold) may
occur; the masking zone may be highly variable in size.
We also describe more severe effects (i.e., certain non-auditory
physical or physiological effects). Potential effects from impulsive
sound sources can range in severity from effects such as behavioral
disturbance or tactile perception to physical discomfort, slight injury
of the internal organs and the auditory system, or mortality (Yelverton
et al., 1973). Non-auditory physiological effects or injuries that
theoretically might occur in marine mammals exposed to high level
underwater sound or as a secondary effect of extreme behavioral
reactions (e.g., change in dive profile as a result of an avoidance
reaction) caused by exposure to sound include neurological effects,
bubble formation, resonance effects, and other types of organ or tissue
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack,
2007; Tal et al., 2015).
Acoustic Sources
Direct Physiological Effects
Non-impulsive sources of sound can cause direct physiological
effects including noise-induced loss of hearing sensitivity (or
``threshold shift''), nitrogen decompression, acoustically-induced
bubble growth, and injury due to sound-induced acoustic resonance. Only
noise-induced hearing loss is anticipated to occur due to the Navy's
activities. Acoustically-induced (or mediated) bubble growth and other
pressure-related physiological impacts are addressed briefly below, but
are not expected to result from the Navy's activities. Separately, an
animal's behavioral reaction to an acoustic exposure might lead to
physiological effects that might ultimately lead to injury or death,
which is discussed later in the Stranding subsection.
Hearing Loss--Threshold Shift
Marine mammals exposed to high-intensity sound, or to lower-
intensity sound for prolonged periods, can experience hearing threshold
shift, which is the loss of hearing sensitivity at certain frequency
ranges after cessation of sound (Finneran, 2015). Threshold shift can
be permanent (PTS), in which case the loss of hearing sensitivity is
not fully recoverable, or temporary (TTS), in which case the animal's
hearing threshold would recover over time (Southall et al., 2007). TTS
can last from minutes or hours to days (i.e., there is recovery back to
baseline/pre-exposure levels), can occur within a specific frequency
range (i.e., an animal might only have a temporary loss of hearing
sensitivity within a limited frequency band of its auditory range), and
can be of varying amounts (e.g., an animal's hearing sensitivity might
be reduced by only 6 dB or reduced by 30 dB). While there is no simple
functional relationship between TTS and PTS or other auditory injury
(e.g., neural degeneration), as TTS increases, the likelihood that
additional exposure sound pressure level (SPL) or duration will result
in PTS or other injury also increases (see also the 2019 MITT DSEIS/
OEIS for additional discussion). Exposure thresholds for the occurrence
of PTS or other auditory injury can therefore be defined based on a
specific amount of TTS; that is, although an exposure has been shown to
produce only TTS, we assume that any additional exposure may result in
some PTS or other injury. The specific upper limit of TTS is based on
experimental data showing amounts of TTS that have not resulted in PTS
or injury. In other words, we do not need to know the exact functional
relationship between TTS and PTS or other injury, we only need to know
the upper limit for TTS before some PTS or injury is possible. In
severe cases of PTS, there can be total or partial deafness, while in
most cases the animal has an impaired ability to hear sounds in
specific frequency ranges (Kryter, 1985).
When PTS occurs, there is physical damage to the sound receptors in
the ear (i.e., tissue damage), whereas TTS represents primarily tissue
fatigue and is reversible (Southall et al., 2007). PTS is permanent
(i.e., there is incomplete recovery back to baseline/pre-exposure
levels), but also can occur in a specific frequency range and amount as
mentioned above for TTS. In addition, other investigators have
suggested that TTS is within the normal bounds of physiological
variability and tolerance and does not represent physical injury (e.g.,
Ward, 1997). Therefore, NMFS does not consider TTS to constitute
auditory injury.
The following physiological mechanisms are thought to play a role
in inducing auditory threshold shift: effects to sensory hair cells in
the inner ear that reduce their sensitivity; modification of the
chemical environment within the sensory cells; residual muscular
activity in the middle ear; displacement of certain inner ear
membranes; increased blood flow; and post-stimulatory reduction in both
efferent and sensory neural output (Southall et al., 2007). The
amplitude, duration, frequency, temporal pattern, and energy
distribution of sound exposure all can affect the amount of associated
threshold shift and the frequency range in which it occurs. Generally,
the amount of threshold shift, and the time needed to recover from the
effect, increase as amplitude and duration of sound exposure increases.
Human non-impulsive noise exposure guidelines are based on the
assumption that exposures of equal energy (the same sound exposure
level (SEL)) produce equal amounts of hearing impairment regardless of
how the sound energy is distributed in time (NIOSH, 1998). Previous
marine mammal TTS studies have also generally supported this equal
energy relationship (Southall et al., 2007). However, some more recent
studies concluded that for all noise exposure situations the equal
energy relationship may not be the best indicator to predict TTS onset
levels (Mooney et al., 2009a and 2009b; Kastak et al., 2007). These
studies highlight the inherent complexity of predicting TTS onset in
marine mammals, as well as the importance of considering exposure
duration when assessing potential impacts. Generally, with sound
exposures of equal energy, those that were quieter (lower SPL) with
longer duration were found to induce TTS onset at lower levels than
those of louder (higher SPL) and shorter duration. Less threshold shift
will occur from intermittent sounds than from a continuous exposure
with the same energy (some recovery can occur between intermittent
exposures) (Kryter et al., 1966; Ward, 1997; Mooney et al., 2009a,
2009b; Finneran et al., 2010). For example, one short but loud (higher
SPL) sound exposure may induce the same impairment as one longer but
softer (lower SPL) sound, which in turn may cause more impairment than
a series of several intermittent softer sounds with the same total
energy (Ward, 1997). Additionally, though TTS is temporary, very
prolonged or
[[Page 5802]]
repeated exposure to sound strong enough to elicit TTS, or shorter-term
exposure to sound levels well above the TTS threshold can cause PTS, at
least in terrestrial mammals (Kryter, 1985; Lonsbury-Martin et al.,
1987). PTS is considered auditory injury (Southall et al., 2007).
Irreparable damage to the inner or outer cochlear hair cells may cause
PTS; however, other mechanisms are also involved, such as exceeding the
elastic limits of certain tissues and membranes in the middle and inner
ears and resultant changes in the chemical composition of the inner ear
fluids (Southall et al., 2007).
The NMFS 2016 Acoustic Technical Guidance (revised in 2018) (NMFS
2016, 2018), which was used in the assessment of effects for this rule,
compiled, interpreted, and synthesized the best available scientific
information for noise-induced hearing effects for marine mammals to
derive updated thresholds for assessing the impacts of noise on marine
mammal hearing. More recently, Southall et al. (2019a) evaluated
Southall et al. (2007) and used updated scientific information to
propose revised noise exposure criteria to predict onset of auditory
effects in marine mammals (i.e., PTS and TTS onset). Southall et al.
(2019a) note that the quantitative processes described and the
resulting exposure criteria (i.e., thresholds and auditory weighting
functions) are largely identical to those in Finneran (2016) and NMFS
(2016 and 2018). They only differ in that the Southall et al. (2019a)
exposure criteria are more broadly applicable as they include all
marine mammal species (rather than only those under NMFS jurisdiction)
for all noise exposures (both in air and underwater for amphibious
species) and, while the hearing group compositions are identical, they
renamed the hearing groups.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019a) for
summaries), however for cetaceans, published data on the onset of TTS
are limited to the captive bottlenose dolphin, beluga, harbor porpoise,
and Yangtze finless porpoise, and for pinnipeds in water, measurements
of TTS are limited to harbor seals, elephant seals, and California sea
lions. These studies examine hearing thresholds measured in marine
mammals before and after exposure to intense sounds. The difference
between the pre-exposure and post-exposure thresholds can then be used
to determine the amount of threshold shift at various post-exposure
times. NMFS has reviewed the available studies, which are summarized
below (see also the 2019 MITT DSEIS/OEIS which includes additional
discussion on TTS studies related to sonar and other transducers):
The method used to test hearing may affect the resulting
amount of measured TTS, with neurophysiological measures producing
larger amounts of TTS compared to psychophysical measures (Finneran et
al., 2007; Finneran, 2015).
The amount of TTS varies with the hearing test frequency.
As the exposure SPL increases, the frequency at which the maximum TTS
occurs also increases (Kastelein et al., 2014b). For high-level
exposures, the maximum TTS typically occurs one-half to one octave
above the exposure frequency (Finneran et al., 2007; Mooney et al.,
2009a; Nachtigall et al., 2004; Popov et al., 2011; Popov et al., 2013;
Schlundt et al., 2000). The overall spread of TTS from tonal exposures
can therefore extend over a large frequency range (i.e., narrowband
exposures can produce broadband (greater than one octave) TTS).
The amount of TTS increases with exposure SPL and duration
and is correlated with SEL, especially if the range of exposure
durations is relatively small (Kastak et al., 2007; Kastelein et al.,
2014b; Popov et al., 2014). As the exposure duration increases,
however, the relationship between TTS and SEL begins to break down.
Specifically, duration has a more significant effect on TTS than would
be predicted on the basis of SEL alone (Finneran et al., 2010a; Kastak
et al., 2005; Mooney et al., 2009a). This means if two exposures have
the same SEL but different durations, the exposure with the longer
duration (thus lower SPL) will tend to produce more TTS than the
exposure with the higher SPL and shorter duration. In most acoustic
impact assessments, the scenarios of interest involve shorter duration
exposures than the marine mammal experimental data from which impact
thresholds are derived; therefore, use of SEL tends to over-estimate
the amount of TTS. Despite this, SEL continues to be used in many
situations because it is relatively simple, more accurate than SPL
alone, and lends itself easily to scenarios involving multiple
exposures with different SPL.
The amount of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity,
are less hazardous than those at higher frequencies, near the region of
best sensitivity (Finneran and Schlundt, 2013). The onset of TTS--
defined as the exposure level necessary to produce 6 dB of TTS (i.e.,
clearly above the typical variation in threshold measurements)--also
varies with exposure frequency. At low frequencies, onset-TTS exposure
levels are higher compared to those in the region of best sensitivity.
TTS can accumulate across multiple exposures, but the
resulting TTS will be less than the TTS from a single, continuous
exposure with the same SEL (Finneran et al., 2010a; Kastelein et al.,
2014b; Kastelein et al., 2015b; Mooney et al., 2009b). This means that
TTS predictions based on the total, cumulative SEL will overestimate
the amount of TTS from intermittent exposures such as sonars and
impulsive sources.
The amount of observed TTS tends to decrease with
increasing time following the exposure; however, the relationship is
not monotonic (i.e., increasing exposure does not always increase TTS).
The time required for complete recovery of hearing depends on the
magnitude of the initial shift; for relatively small shifts recovery
may be complete in a few minutes, while large shifts (e.g.,
approximately 40 dB) may require several days for recovery. Under many
circumstances TTS recovers linearly with the logarithm of time
(Finneran et al., 2010a, 2010b; Finneran and Schlundt, 2013; Kastelein
et al., 2012a; Kastelein et al., 2012b; Kastelein et al., 2013a;
Kastelein et al., 2014b; Kastelein et al., 2014c; Popov et al., 2011;
Popov et al., 2013; Popov et al., 2014). This means that for each
doubling of recovery time, the amount of TTS will decrease by the same
amount (e.g., 6 dB recovery per doubling of time).
Nachtigall et al. (2018) and Finneran (2018) describe the
measurements of hearing sensitivity of multiple odontocete species
(bottlenose dolphin, harbor porpoise, beluga, and false killer whale)
when a relatively loud sound was preceded by a warning sound. These
captive animals were shown to reduce hearing sensitivity when warned of
an impending intense sound. Based on these experimental observations of
captive animals, the authors suggest that wild animals may dampen their
hearing during prolonged exposures or if conditioned to anticipate
intense sounds. Finneran recommends further investigation of the
mechanisms of hearing sensitivity reduction in order to understand the
implications for interpretation of existing TTS data obtained from
captive animals, notably for considering TTS due to short duration,
unpredictable exposures.
Marine mammal hearing plays a critical role in communication with
conspecifics and in interpretation of
[[Page 5803]]
environmental cues for purposes such as predator avoidance and prey
capture. Depending on the degree (elevation of threshold in dB),
duration (i.e., recovery time), and frequency range of TTS, and the
context in which it is experienced, TTS can have effects on marine
mammals ranging from discountable to serious similar to those discussed
in auditory masking, below. For example, a marine mammal may be able to
readily compensate for a brief, relatively small amount of TTS in a
non-critical frequency range that takes place during a time where
ambient noise is lower and there are not as many competing sounds
present. Alternatively, a larger amount and longer duration of TTS
sustained during a time when communication is critical for successful
mother/calf interactions could have more serious impacts if it were in
the same frequency band as the necessary vocalizations and of a
severity that impeded communication. The fact that animals exposed to
high levels of sound that would be expected to result in this
physiological response would also be expected to have behavioral
responses of a comparatively more severe or sustained nature is
potentially more significant than simple existence of a TTS. However,
it is important to note that TTS could occur due to longer exposures to
sound at lower levels so that a behavioral response may not be
elicited. Depending on the degree and frequency range, the effects of
PTS on an animal could also range in severity, although it is
considered generally more serious than TTS because it is a permanent
condition. Of note, reduced hearing sensitivity as a simple function of
aging has been observed in marine mammals, as well as humans and other
taxa (Southall et al., 2007), so we can infer that strategies exist for
coping with this condition to some degree, though likely not without
some cost to the animal.
Acoustically-Induced Bubble Formation Due to Sonars and Other Pressure-
Related Impacts
One theoretical cause of injury to marine mammals is rectified
diffusion (Crum and Mao, 1996), the process of increasing the size of a
bubble by exposing it to a sound field. This process could be
facilitated if the environment in which the ensonified bubbles exist is
supersaturated with gas. Repetitive diving by marine mammals can cause
the blood and some tissues to accumulate gas to a greater degree than
is supported by the surrounding environmental pressure (Ridgway and
Howard, 1979). The deeper and longer dives of some marine mammals (for
example, beaked whales) are theoretically predicted to induce greater
supersaturation (Houser et al., 2001b). If rectified diffusion were
possible in marine mammals exposed to high-level sound, conditions of
tissue supersaturation could theoretically speed the rate and increase
the size of bubble growth. Subsequent effects due to tissue trauma and
emboli would presumably mirror those observed in humans suffering from
decompression sickness.
It is unlikely that the short duration (in combination with the
source levels) of sonar pings would be long enough to drive bubble
growth to any substantial size, if such a phenomenon occurs. However,
an alternative but related hypothesis has also been suggested: stable
bubbles could be destabilized by high-level sound exposures such that
bubble growth then occurs through static diffusion of gas out of the
tissues. In such a scenario the marine mammal would need to be in a
gas-supersaturated state for a long enough period of time for bubbles
to become of a problematic size. Recent research with ex vivo
supersaturated bovine tissues suggested that, for a 37 kHz signal, a
sound exposure of approximately 215 dB referenced to (re) 1 [mu]Pa
would be required before microbubbles became destabilized and grew
(Crum et al., 2005). Assuming spherical spreading loss and a nominal
sonar source level of 235 dB re 1 [mu]Pa at 1 m, a whale would need to
be within 10 m (33 ft) of the sonar dome to be exposed to such sound
levels. Furthermore, tissues in the study were supersaturated by
exposing them to pressures of 400-700 kilopascals for periods of hours
and then releasing them to ambient pressures. Assuming the
equilibration of gases with the tissues occurred when the tissues were
exposed to the high pressures, levels of supersaturation in the tissues
could have been as high as 400-700 percent. These levels of tissue
supersaturation are substantially higher than model predictions for
marine mammals (Houser et al., 2001; Saunders et al., 2008). It is
improbable that this mechanism is responsible for stranding events or
traumas associated with beaked whale strandings because both the degree
of supersaturation and exposure levels observed to cause microbubble
destabilization are unlikely to occur, either alone or in concert.
Yet another hypothesis (decompression sickness) has speculated that
rapid ascent to the surface following exposure to a startling sound
might produce tissue gas saturation sufficient for the evolution of
nitrogen bubbles (Jepson et al., 2003; Fernandez et al., 2005;
Fern[aacute]ndez et al., 2012). In this scenario, the rate of ascent
would need to be sufficiently rapid to compromise behavioral or
physiological protections against nitrogen bubble formation.
Alternatively, Tyack et al. (2006) studied the deep diving behavior of
beaked whales and concluded that: ``Using current models of breath-hold
diving, we infer that their natural diving behavior is inconsistent
with known problems of acute nitrogen supersaturation and embolism.''
Collectively, these hypotheses can be referred to as ``hypotheses of
acoustically mediated bubble growth.''
Although theoretical predictions suggest the possibility for
acoustically mediated bubble growth, there is considerable disagreement
among scientists as to its likelihood (Piantadosi and Thalmann, 2004;
Evans and Miller, 2003; Cox et al., 2006; Rommel et al., 2006). Crum
and Mao (1996) hypothesized that received levels would have to exceed
190 dB in order for there to be the possibility of significant bubble
growth due to supersaturation of gases in the blood (i.e., rectified
diffusion). Work conducted by Crum et al. (2005) demonstrated the
possibility of rectified diffusion for short duration signals, but at
SELs and tissue saturation levels that are highly improbable to occur
in diving marine mammals. To date, energy levels (ELs) predicted to
cause in vivo bubble formation within diving cetaceans have not been
evaluated (NOAA, 2002b). Jepson et al. (2003, 2005) and Fernandez et
al. (2004, 2005, 2012) concluded that in vivo bubble formation, which
may be exacerbated by deep, long-duration, repetitive dives may explain
why beaked whales appear to be relatively vulnerable to MF/HF sonar
exposures. It has also been argued that traumas from some beaked whale
strandings are consistent with gas emboli and bubble-induced tissue
separations (Jepson et al., 2003); however, there is no conclusive
evidence of this (Rommel et al., 2006).
As described in additional detail in the Nitrogen Decompression
subsection of the 2019 MITT DSEIS/OEIS, marine mammals generally are
thought to deal with nitrogen loads in their blood and other tissues,
caused by gas exchange from the lungs under conditions of high ambient
pressure during diving, through anatomical, behavioral, and
physiological adaptations (Hooker et al., 2012). Although not a direct
injury, variations in marine mammal diving behavior or avoidance
responses have been hypothesized to result in nitrogen off-gassing in
super-saturated tissues, possibly to the point of deleterious
[[Page 5804]]
vascular and tissue bubble formation (Hooker et al., 2012; Jepson et
al., 2003; Saunders et al., 2008) with resulting symptoms similar to
decompression sickness, however the process is still not well
understood.
In 2009, Hooker et al. tested two mathematical models to predict
blood and tissue tension N2 (PN2) using field data from
three beaked whale species: northern bottlenose whales, Cuvier's beaked
whales, and Blainville's beaked whales. The researchers aimed to
determine if physiology (body mass, diving lung volume, and dive
response) or dive behavior (dive depth and duration, changes in ascent
rate, and diel behavior) would lead to differences in PN2
levels and thereby decompression sickness risk between species. In
their study, they compared results for previously published time depth
recorder data (Hooker and Baird, 1999; Baird et al., 2006, 2008) from
Cuvier's beaked whale, Blainville's beaked whale, and northern
bottlenose whale. They reported that diving lung volume and extent of
the dive response had a large effect on end-dive PN2. Also,
results showed that dive profiles had a larger influence on end-dive
PN2 than body mass differences between species. Despite diel
changes (i.e., variation that occurs regularly every day or most days)
in dive behavior, PN2 levels showed no consistent trend.
Model output suggested that all three species live with tissue
PN2 levels that would cause a significant proportion of
decompression sickness cases in terrestrial mammals. The authors
concluded that the dive behavior of Cuvier's beaked whale was different
from both Blainville's beaked whale, and northern bottlenose whale, and
resulted in higher predicted tissue and blood N2 levels (Hooker et al.,
2009). They also suggested that the prevalence of Cuvier's beaked
whales stranding after naval sonar exercises could be explained by
either a higher abundance of this species in the affected areas or by
possible species differences in behavior and/or physiology related to
MF active sonar (Hooker et al., 2009).
Bernaldo de Quiros et al. (2012) showed that, among stranded
whales, deep diving species of whales had higher abundances of gas
bubbles compared to shallow diving species. Kvadsheim et al. (2012)
estimated blood and tissue PN2 levels in species
representing shallow, intermediate, and deep diving cetaceans following
behavioral responses to sonar and their comparisons found that deep
diving species had higher end-dive blood and tissue N2
levels, indicating a higher risk of developing gas bubble emboli
compared with shallow diving species. Fahlmann et al. (2014) evaluated
dive data recorded from sperm, killer, long-finned pilot, Blainville's
beaked and Cuvier's beaked whales before and during exposure to low-
frequency (1-2 kHz), as defined by the authors, and mid-frequency (2-7
kHz) active sonar in an attempt to determine if either differences in
dive behavior or physiological responses to sonar are plausible risk
factors for bubble formation. The authors suggested that CO2
may initiate bubble formation and growth, while elevated levels of
N2 may be important for continued bubble growth. The authors
also suggest that if CO2 plays an important role in bubble
formation, a cetacean escaping a sound source may experience increased
metabolic rate, CO2 production, and alteration in cardiac
output, which could increase risk of gas bubble emboli. However, as
discussed in Kvadsheim et al. (2012), the actual observed behavioral
responses to sonar from the species in their study (sperm, killer,
long-finned pilot, Blainville's beaked, and Cuvier's beaked whales) did
not imply any significantly increased risk of decompression sickness
due to high levels of N2. Therefore, further information is
needed to understand the relationship between exposure to stimuli,
behavioral response (discussed in more detail below), elevated
N2 levels, and gas bubble emboli in marine mammals. The
hypotheses for gas bubble formation related to beaked whale strandings
is that beaked whales potentially have strong avoidance responses to MF
active sonars because they sound similar to their main predator, the
killer whale (Cox et al., 2006; Southall et al., 2007; Zimmer and
Tyack, 2007; Baird et al., 2008; Hooker et al., 2009). Further
investigation is needed to assess the potential validity of these
hypotheses.
To summarize, while there are several hypotheses, there is little
data directly connecting intense, anthropogenic underwater sounds with
non-auditory physical effects in marine mammals. The available data do
not support identification of a specific exposure level above which
non-auditory effects can be expected (Southall et al., 2007) or any
meaningful quantitative predictions of the numbers (if any) of marine
mammals that might be affected in these ways. In addition, such
effects, if they occur at all, would be expected to be limited to
situations where marine mammals were exposed to high powered sounds at
very close range over a prolonged period of time, which is not expected
to occur based on the speed of the vessels operating sonar in
combination with the speed and behavior of marine mammals in the
vicinity of sonar.
Injury Due to Sonar-Induced Acoustic Resonance
An object exposed to its resonant frequency will tend to amplify
its vibration at that frequency, a phenomenon called acoustic
resonance. Acoustic resonance has been proposed as a potential
mechanism by which a sonar or sources with similar operating
characteristics could damage tissues of marine mammals. In 2002, NMFS
convened a panel of government and private scientists to investigate
the potential for acoustic resonance to occur in marine mammals
(National Oceanic and Atmospheric Administration, 2002). They modeled
and evaluated the likelihood that Navy mid-frequency sonar (2-10 kHz)
caused resonance effects in beaked whales that eventually led to their
stranding. The workshop participants concluded that resonance in air-
filled structures was not likely to have played a primary role in the
Bahamas stranding in 2000. They listed several reasons supporting this
finding including (among others): Tissue displacements at resonance are
estimated to be too small to cause tissue damage; tissue-lined air
spaces most susceptible to resonance are too large in marine mammals to
have resonant frequencies in the ranges used by mid-frequency or low-
frequency sonar; lung resonant frequencies increase with depth, and
tissue displacements decrease with depth so if resonance is more likely
to be caused at depth it is also less likely to have an affect there;
and lung tissue damage has not been observed in any mass, multi-species
stranding of beaked whales. The frequency at which resonance was
predicted to occur in the animals' lungs was 50 Hz, well below the
frequencies used by the mid-frequency sonar systems associated with the
Bahamas event. The workshop participants focused on the March 2000
stranding of beaked whales in the Bahamas as high-quality data were
available, but the workshop report notes that the results apply to
other sonar-related stranding events. For the reasons given by the 2002
workshop participants, we do not anticipate injury due to sonar-induced
acoustic resonance from the Navy's proposed activities.
Physiological Stress
There is growing interest in monitoring and assessing the impacts
of stress responses to sound in marine animals. Classic stress
responses begin when an animal's central nervous
[[Page 5805]]
system perceives a potential threat to its homeostasis. That perception
triggers stress responses regardless of whether a stimulus actually
threatens the animal; the mere perception of a threat is sufficient to
trigger a stress response (Moberg, 2000; Sapolsky et al., 2005; Seyle,
1950). Once an animal's central nervous system perceives a threat, it
mounts a biological response or defense that consists of a combination
of the four general biological defense responses: Behavioral responses,
autonomic nervous system responses, neuroendocrine responses, or immune
responses.
According to Moberg (2000), in the case of many stressors, an
animal's first and sometimes most economical (in terms of biotic costs)
response is behavioral avoidance of the potential stressor or avoidance
of continued exposure to a stressor. An animal's second line of defense
to stressors involves the sympathetic part of the autonomic nervous
system and the classical ``fight or flight'' response which includes
the cardiovascular system, the gastrointestinal system, the exocrine
glands, and the adrenal medulla to produce changes in heart rate, blood
pressure, and gastrointestinal activity that humans commonly associate
with ``stress.'' These responses have a relatively short duration and
may or may not have significant long-term effect on an animal's
welfare.
An animal's third line of defense to stressors involves its
neuroendocrine systems or sympathetic nervous systems; the system that
has received the most study has been the hypothalmus-pituitary-adrenal
system (also known as the HPA axis in mammals or the hypothalamus-
pituitary-interrenal axis in fish and some reptiles). Unlike stress
responses associated with the autonomic nervous system, virtually all
neuro-endocrine functions that are affected by stress--including immune
competence, reproduction, metabolism, and behavior--are regulated by
pituitary hormones. Stress-induced changes in the secretion of
pituitary hormones have been implicated in failed reproduction (Moberg,
1987; Rivier and Rivest, 1991), altered metabolism (Elasser et al.,
2000), reduced immune competence (Blecha, 2000), and behavioral
disturbance (Moberg, 1987; Blecha, 2000). Increases in the circulation
of glucocorticosteroids (cortisol, corticosterone, and aldosterone in
marine mammals; see Romano et al., 2004) have been equated with stress
for many years.
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and distress is the biotic cost
of the response. During a stress response, an animal uses glycogen
stores that can be quickly replenished once the stress is alleviated.
In such circumstances, the cost of the stress response would not pose
serious fitness consequences. However, when an animal does not have
sufficient energy reserves to satisfy the energetic costs of a stress
response, energy resources must be diverted from other biotic
functions, which impairs those functions that experience the diversion.
For example, when a stress response diverts energy away from growth in
young animals, those animals may experience stunted growth. When a
stress response diverts energy from a fetus, an animal's reproductive
success and its fitness will suffer. In these cases, the animals will
have entered a pre-pathological or pathological state which is called
``distress'' (Seyle, 1950) or ``allostatic loading'' (McEwen and
Wingfield, 2003). This pathological state of distress will last until
the animal replenishes its energetic reserves sufficiently to restore
normal function. Note that these examples involved a long-term (days or
weeks) stress response exposure to stimuli.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments in both laboratory and free-ranging animals (for
examples see, Holberton et al., 1996; Hood et al., 1998; Jessop et al.,
2003; Krausman et al., 2004; Lankford et al., 2005; Reneerkens et al.,
2002; Thompson and Hamer, 2000). However, it should be noted (and as is
described in additional detail in the 2019 MITT DSEIS/OEIS) that our
understanding of the functions of various stress hormones (for example,
cortisol), is based largely upon observations of the stress response in
terrestrial mammals. Atkinson et al., 2015 note that the endocrine
response of marine mammals to stress may not be the same as that of
terrestrial mammals because of the selective pressures marine mammals
faced during their evolution in an ocean environment. For example, due
to the necessity of breath-holding while diving and foraging at depth,
the physiological role of epinephrine and norepinephrine (the
catecholamines) in marine mammals might be different than in other
mammals.
As described in the 2019 MITT DSEIS/OEIS, marine mammals naturally
experience stressors within their environment and as part of their life
histories. Changing weather and ocean conditions, exposure to disease
and naturally occurring toxins, lack of prey availability, and
interactions with predators all contribute to the stress a marine
mammal experiences (Atkinson et al., 2015). Breeding cycles, periods of
fasting, and social interactions with members of the same species are
also stressors, although they are natural components of an animal's
life history. Anthropogenic activities have the potential to provide
additional stressors beyond those that occur naturally (Fair et al.,
2014; Meissner et al., 2015; Rolland et al., 2012). Anthropogenic
stressors potentially include such things as fishery interactions,
pollution, tourism, and ocean noise.
Acoustically induced stress in marine mammals is not well
understood. There are ongoing efforts to improve our understanding of
how stressors impact marine mammal populations (see Navy funded
examples here: e.g., King et al., 2015; New et al., 2013a; New et al.,
2013b; Pirotta et al., 2015a), however little data exist on the
consequences of sound-induced stress response (acute or chronic).
Factors potentially affecting a marine mammal's response to a stressor
include the individual's life history stage, sex, age, reproductive
status, overall physiological and behavioral plasticity, and whether
they are na[iuml]ve or experienced with the sound (e.g., prior
experience with a stressor may result in a reduced response due to
habituation (Finneran and Branstetter, 2013; St. Aubin and Dierauf,
2001a)). Stress responses due to exposure to anthropogenic sounds or
other stressors and their effects on marine mammals have been reviewed
(Fair and Becker, 2000; Romano et al., 2002b) and, more rarely, studied
in wild populations (e.g., Romano et al., 2002a). For example, Rolland
et al. (2012) found that noise reduction from reduced ship traffic in
the Bay of Fundy was associated with decreased stress in North Atlantic
right whales. These and other studies lead to a reasonable expectation
that some marine mammals will experience physiological stress responses
upon exposure to acoustic stressors and that it is possible that some
of these would be classified as ``distress.'' In addition, any animal
experiencing TTS would likely also experience stress responses (NRC,
2003).
Other research has also investigated the impact from vessels (both
whale-watching and general vessel traffic noise), and demonstrated
impacts do occur (Bain, 2002; Erbe, 2002; Lusseau, 2006; Williams et
al., 2006; Williams et al., 2009; Noren et al., 2009; Read et al.,
2014; Rolland et al., 2012; Skarke et al., 2014; Williams et al., 2013;
Williams et al., 2014a; Williams et al., 2014b; Pirotta et al., 2015).
This body of research has
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generally investigated impacts associated with the presence of chronic
stressors, which differ significantly from the proposed Navy training
and testing vessel activities in the MITT Study Area. For example, in
an analysis of energy costs to killer whales, Williams et al. (2009)
suggested that whale-watching in Canada's Johnstone Strait resulted in
lost feeding opportunities due to vessel disturbance, which could carry
higher costs than other measures of behavioral change might suggest.
Ayres et al. (2012) reported on research in the Salish Sea (Washington
state) involving the measurement of southern resident killer whale
fecal hormones to assess two potential threats to the species recovery:
Lack of prey (salmon) and impacts to behavior from vessel traffic.
Ayres et al. (2012) suggested that the lack of prey overshadowed any
population-level physiological impacts on southern resident killer
whales from vessel traffic. In a conceptual model developed by the
Population Consequences of Acoustic Disturbance (PCAD) working group,
serum hormones were identified as possible indicators of behavioral
effects that are translated into altered rates of reproduction and
mortality (NRC, 2005). The Office of Naval Research hosted a workshop
(Effects of Stress on Marine Mammals Exposed to Sound) in 2009 that
focused on this topic (ONR, 2009). Ultimately, the PCAD working group
issued a report (Cochrem, 2014) that summarized information compiled
from 239 papers or book chapters relating to stress in marine mammals
and concluded that stress responses can last from minutes to hours and,
while we typically focus on adverse stress responses, stress response
is part of a natural process to help animals adjust to changes in their
environment and can also be either neutral or beneficial.
Most sound-induced stress response studies in marine mammals have
focused on acute responses to sound either by measuring catecholamines
or by measuring heart rate as an assumed proxy for an acute stress
response. As described in the 2019 MITT DSEIS/OEIS, belugas
demonstrated no catecholamine response to the playback of oil drilling
sounds (Thomas et al., 1990) but showed a small but statistically
significant increase in catecholamines following exposure to impulsive
sounds produced from a seismic water gun (Romano et al., 2004). A
bottlenose dolphin exposed to the same seismic water gun signals did
not demonstrate a catecholamine response, but did demonstrate a
statistically significant elevation in aldosterone (Romano et al.,
2004), albeit the increase was within the normal daily variation
observed in this species (St. Aubin et al., 1996). Increases in heart
rate were observed in bottlenose dolphins to which known calls of other
dolphins were played, although no increase in heart rate was observed
when background tank noise was played back (Miksis et al., 2001).
Unfortunately, in this study, it cannot be determined whether the
increase in heart rate was due to stress or an anticipation of being
reunited with the dolphin to which the vocalization belonged.
Similarly, a young beluga's heart rate was observed to increase during
exposure to noise, with increases dependent upon the frequency band of
noise and duration of exposure, and with a sharp decrease to normal or
below normal levels upon cessation of the exposure (Lyamin et al.,
2011). Spectral analysis of heart rate variability corroborated direct
measures of heart rate (Bakhchina et al., 2017). This response might
have been in part due to the conditions during testing, the young age
of the animal, and the novelty of the exposure; a year later the
exposure was repeated at a slightly higher received level and there was
no heart rate response, indicating the beluga whale may have acclimated
to the noise exposure. Kvadsheim et al. (2010) measured the heart rate
of captive hooded seals during exposure to sonar signals and found an
increase in the heart rate of the seals during exposure periods versus
control periods when the animals were at the surface. When the animals
dove, the normal dive-related bradycardia (decrease in heart rate) was
not impacted by the sonar exposure. Similarly, Thompson et al. (1998)
observed a rapid but short-lived decrease in heart rates in harbor and
grey seals exposed to seismic air guns (cited in Gordon et al., 2003).
Williams et al. (2017) recently monitored the heart rates of narwhals
released from capture and found that a profound dive bradycardia
persisted, even though exercise effort increased dramatically as part
of their escape response following release. Thus, although some limited
evidence suggests that tachycardia might occur as part of the acute
stress response of animals that are at the surface, the dive
bradycardia persists during diving and might be enhanced in response to
an acute stressor.
Despite the limited amount of data available on sound-induced
stress responses for marine mammals exposed to anthropogenic sounds,
studies of other marine animals and terrestrial animals would also lead
us to expect that some marine mammals experience physiological stress
responses and, perhaps, physiological responses that would be
classified as ``distress'' upon exposure to high- frequency, mid-
frequency, and low-frequency sounds. For example, Jansen (1998)
reported on the relationship between acoustic exposures and
physiological responses that are indicative of stress responses in
humans (e.g., elevated respiration and increased heart rates). Jones
(1998) reported on reductions in human performance when faced with
acute, repetitive exposures to acoustic disturbance. Trimper et al.
(1998) reported on the physiological stress responses of osprey to low-
level aircraft noise while Krausman et al. (2004) reported on the
auditory and physiological stress responses of endangered Sonoran
pronghorn to military overflights. However, take due to aircraft noise
is not anticipated as a result of the Navy's activities. Smith et al.
(2004a, 2004b) identified noise-induced physiological transient stress
responses in hearing-specialist fish (i.e., goldfish) that accompanied
short- and long-term hearing losses. Welch and Welch (1970) reported
physiological and behavioral stress responses that accompanied damage
to the inner ears of fish and several mammals.
Auditory Masking
Sound can disrupt behavior through masking, or interfering with, an
animal's ability to detect, recognize, or discriminate between acoustic
signals of interest (e.g., those used for intraspecific communication
and social interactions, prey detection, predator avoidance, or
navigation) (Richardson et al., 1995; Erbe and Farmer, 2000; Tyack,
2000; Erbe et al., 2016). Masking occurs when the receipt of a sound is
interfered with by another coincident sound at similar frequencies and
at similar or higher intensity, and may occur whether the sound is
natural (e.g., snapping shrimp, wind, waves, precipitation) or
anthropogenic (e.g., shipping, sonar, seismic exploration) in origin.
As described in detail in the 2019 MITT DSEIS/OEIS, the ability of a
noise source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest
(e.g., signal-to-noise ratio, temporal variability, direction), in
relation to each other and to an animal's hearing abilities (e.g.,
sensitivity, frequency range, critical ratios, frequency
discrimination, directional discrimination, age, or TTS hearing loss),
and existing ambient noise and propagation conditions. Masking these
acoustic signals can disturb the behavior
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of individual animals, groups of animals, or entire populations.
Masking can lead to behavioral changes including vocal changes (e.g.,
Lombard effect, increasing amplitude, or changing frequency), cessation
of foraging, and leaving an area, to both signalers and receivers, in
an attempt to compensate for noise levels (Erbe et al., 2016). In
humans, significant masking of tonal signals occurs as a result of
exposure to noise in a narrow band of similar frequencies. As the sound
level increases, though, the detection of frequencies above those of
the masking stimulus decreases also. This principle is expected to
apply to marine mammals as well because of common biomechanical
cochlear properties across taxa.
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is man-made, it may be considered harassment
when disrupting or altering critical behaviors. It is important to
distinguish TTS and PTS, which persist after the sound exposure, from
masking, which only occurs during the sound exposure. Because masking
(without resulting in threshold shift) is not associated with abnormal
physiological function, it is not considered a physiological effect,
but rather a potential behavioral effect.
Richardson et al. (1995b) argued that the maximum radius of
influence of an industrial noise (including broadband low-frequency
sound transmission) on a marine mammal is the distance from the source
to the point at which the noise can barely be heard. This range is
determined by either the hearing sensitivity (including critical
ratios, or the lowest signal-to-noise ratio in which animals can detect
a signal, Finneran and Branstetter, 2013; Johnson et al., 1989;
Southall et al., 2000) of the animal or the background noise level
present. Industrial masking is most likely to affect some species'
ability to detect communication calls and natural sounds (i.e., surf
noise, prey noise, etc.; Richardson et al., 1995).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009; Matthews et al., 2016) and may result in energetic
or other costs as animals change their vocalization behavior (e.g.,
Miller et al., 2000; Foote et al., 2004; Parks et al., 2007; Di Iorio
and Clark, 2009; Holt et al., 2009). Masking can be reduced in
situations where the signal and noise come from different directions
(Richardson et al., 1995), through amplitude modulation of the signal,
or through other compensatory behaviors (Houser and Moore, 2014).
Masking can be tested directly in captive species (e.g., Erbe, 2008),
but in wild populations it must be either modeled or inferred from
evidence of masking compensation. There are few studies addressing
real-world masking sounds likely to be experienced by marine mammals in
the wild (e.g., Branstetter et al., 2013).
The echolocation calls of toothed whales are subject to masking by
high-frequency sound. Human data indicate low-frequency sound can mask
high-frequency sounds (i.e., upward masking). Studies on captive
odontocetes by Au et al. (1974, 1985, 1993) indicate that some species
may use various processes to reduce masking effects (e.g., adjustments
in echolocation call intensity or frequency as a function of background
noise conditions). There is also evidence that the directional hearing
abilities of odontocetes are useful in reducing masking at the high-
frequencies these cetaceans use to echolocate, but not at the low-to-
moderate frequencies they use to communicate (Zaitseva et al., 1980). A
study by Nachtigall and Supin (2008) showed that false killer whales
adjust their hearing to compensate for ambient sounds and the intensity
of returning echolocation signals.
Impacts on signal detection, measured by masked detection
thresholds, are not the only important factors to address when
considering the potential effects of masking. As marine mammals use
sound to recognize conspecifics, prey, predators, or other biologically
significant sources (Branstetter et al., 2016), it is also important to
understand the impacts of masked recognition thresholds (often called
``informational masking''). Branstetter et al., 2016 measured masked
recognition thresholds for whistle-like sounds of bottlenose dolphins
and observed that they are approximately 4 dB above detection
thresholds (energetic masking) for the same signals. Reduced ability to
recognize a conspecific call or the acoustic signature of a predator
could have severe negative impacts. Branstetter et al., 2016 observed
that if ``quality communication'' is set at 90 percent recognition the
output of communication space models (which are based on 50 percent
detection) would likely result in a significant decrease in
communication range.
As marine mammals use sound to recognize predators (Allen et al.,
2014; Cummings and Thompson, 1971; Cur[eacute] et al., 2015; Fish and
Vania, 1971), the presence of masking noise may also prevent marine
mammals from responding to acoustic cues produced by their predators,
particularly if it occurs in the same frequency band. For example,
harbor seals that reside in the coastal waters off British Columbia are
frequently targeted by mammal-eating killer whales. The seals
acoustically discriminate between the calls of mammal-eating and fish-
eating killer whales (Deecke et al., 2002), a capability that should
increase survivorship while reducing the energy required to attend to
all killer whale calls. Similarly, sperm whales (Cur[eacute] et al.,
2016; Isojunno et al., 2016), long-finned pilot whales (Visser et al.,
2016), and humpback whales (Cur[eacute] et al., 2015) changed their
behavior in response to killer whale vocalization playbacks; these
findings indicate that some recognition of predator cues could be
missed if the killer whale vocalizations were masked. The potential
effects of masked predator acoustic cues depends on the duration of the
masking noise and the likelihood of a marine mammal encountering a
predator during the time that detection and recognition of predator
cues are impeded.
Redundancy and context can also facilitate detection of weak
signals. These phenomena may help marine mammals detect weak sounds in
the presence of natural or manmade noise. Most masking studies in
marine mammals present the test signal and the masking noise from the
same direction. The dominant background noise may be highly directional
if it comes from a particular anthropogenic source such as a ship or
industrial site. Directional hearing may significantly reduce the
masking effects of these sounds by improving the effective signal-to-
noise ratio.
Masking affects both senders and receivers of acoustic signals and
can potentially have long-term chronic effects on marine mammals at the
population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than
three times in terms of SPL) in the world's ocean from pre-industrial
periods, with most
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of the increase from distant commercial shipping (Hildebrand, 2009).
All anthropogenic sound sources, but especially chronic and lower-
frequency signals (e.g., from commercial vessel traffic), contribute to
elevated ambient sound levels, thus intensifying masking.
Impaired Communication
In addition to making it more difficult for animals to perceive and
recognize acoustic cues in their environment, anthropogenic sound
presents separate challenges for animals that are vocalizing. When they
vocalize, animals are aware of environmental conditions that affect the
``active space'' (or communication space) of their vocalizations, which
is the maximum area within which their vocalizations can be detected
before it drops to the level of ambient noise (Brenowitz, 2004; Brumm
et al., 2004; Lohr et al., 2003). Animals are also aware of
environmental conditions that affect whether listeners can discriminate
and recognize their vocalizations from other sounds, which is more
important than simply detecting that a vocalization is occurring
(Brenowitz, 1982; Brumm et al., 2004; Dooling, 2004, Marten and Marler,
1977; Patricelli et al., 2006). Most species that vocalize have evolved
with an ability to make adjustments to their vocalizations to increase
the signal-to-noise ratio, active space, and recognizability/
distinguishability of their vocalizations in the face of temporary
changes in background noise (Brumm et al., 2004; Patricelli et al.,
2006). Vocalizing animals can make adjustments to vocalization
characteristics such as the frequency structure, amplitude, temporal
structure, and temporal delivery (repetition rate), or ceasing to
vocalize.
Many animals will combine several of these strategies to compensate
for high levels of background noise. Anthropogenic sounds that reduce
the signal-to-noise ratio of animal vocalizations, increase the masked
auditory thresholds of animals listening for such vocalizations, or
reduce the active space of an animal's vocalizations impair
communication between animals. Most animals that vocalize have evolved
strategies to compensate for the effects of short-term or temporary
increases in background or ambient noise on their songs or calls.
Although the fitness consequences of these vocal adjustments are not
directly known in all instances, like most other trade-offs animals
must make, some of these strategies probably come at a cost (Patricelli
et al., 2006). Shifting songs and calls to higher frequencies may also
impose energetic costs (Lambrechts, 1996). For example in birds,
vocalizing more loudly in noisy environments may have energetic costs
that decrease the net benefits of vocal adjustment and alter a bird's
energy budget (Brumm, 2004; Wood and Yezerinac, 2006).
Marine mammals are also known to make vocal changes in response to
anthropogenic noise. In cetaceans, vocalization changes have been
reported from exposure to anthropogenic noise sources such as sonar,
vessel noise, and seismic surveying (see the following for examples:
Gordon et al., 2003; Di Iorio and Clark, 2010; Hatch et al., 2012; Holt
et al., 2008; Holt et al., 2011; Lesage et al., 1999; McDonald et al.,
2009; Parks et al., 2007, Risch et al., 2012, Rolland et al., 2012), as
well as changes in the natural acoustic environment (Dunlop et al.,
2014). Vocal changes can be temporary, or can be persistent. For
example, model simulation suggests that the increase in starting
frequency for the North Atlantic right whale upcall over the last 50
years resulted in increased detection ranges between right whales. The
frequency shift, coupled with an increase in call intensity by 20 dB,
led to a call detectability range of less than 3 km to over 9 km
(Tennessen and Parks, 2016). Holt et al. (2008) measured killer whale
call source levels and background noise levels in the one to 40 kHz
band and reported that the whales increased their call source levels by
one dB SPL for every one dB SPL increase in background noise level.
Similarly, another study on St. Lawrence River belugas reported a
similar rate of increase in vocalization activity in response to
passing vessels (Scheifele et al., 2005). Di Iorio and Clark (2010)
showed that blue whale calling rates vary in association with seismic
sparker survey activity, with whales calling more on days with surveys
than on days without surveys. They suggested that the whales called
more during seismic survey periods as a way to compensate for the
elevated noise conditions.
In some cases, these vocal changes may have fitness consequences,
such as an increase in metabolic rates and oxygen consumption, as
observed in bottlenose dolphins when increasing their call amplitude
(Holt et al., 2015). A switch from vocal communication to physical,
surface-generated sounds such as pectoral fin slapping or breaching was
observed for humpback whales in the presence of increasing natural
background noise levels, indicating that adaptations to masking may
also move beyond vocal modifications (Dunlop et al., 2010).
While these changes all represent possible tactics by the sound-
producing animal to reduce the impact of masking, the receiving animal
can also reduce masking by using active listening strategies such as
orienting to the sound source, moving to a quieter location, or
reducing self-noise from hydrodynamic flow by remaining still. The
temporal structure of noise (e.g., amplitude modulation) may also
provide a considerable release from masking through comodulation
masking release (a reduction of masking that occurs when broadband
noise, with a frequency spectrum wider than an animal's auditory filter
bandwidth at the frequency of interest, is amplitude modulated)
(Branstetter and Finneran, 2008; Branstetter et al., 2013). Signal type
(e.g., whistles, burst-pulse, sonar clicks) and spectral
characteristics (e.g., frequency modulated with harmonics) may further
influence masked detection thresholds (Branstetter et al., 2016;
Cunningham et al., 2014).
Masking Due to Sonar and Other Transducers
The functional hearing ranges of mysticetes, odontocetes, and
pinnipeds underwater overlap the frequencies of the sonar sources used
in the Navy's low-frequency active sonar (LFAS)/mid-frequency active
sonar (MFAS)/high-frequency active sonar (HFAS) training and testing
exercises. Additionally, almost all species' vocal repertoires span
across the frequencies of these sonar sources used by the Navy. The
closer the characteristics of the masking signal to the signal of
interest, the more likely masking is to occur. Masking by low-frequency
or mid-frequency active sonar (LFAS and MFAS) with relatively low-duty
cycles is not anticipated (or would be of very short duration) for most
cetaceans as sonar signals occur over a relatively short duration and
narrow bandwidth (overlapping with only a small portion of the hearing
range). LFAS could overlap in frequency with mysticete vocalizations,
however LFAS and MFAS does not overlap with vocalizations for most
marine mammal species. For example, in the presence of LFAS, humpback
whales were observed to increase the length of their songs (Fristrup et
al., 2003; Miller et al., 2000), potentially due to the overlap in
frequencies between the whale song and the LFAS. While dolphin whistles
and MFAS are similar in frequency, masking is not anticipated (or would
be of very short duration) due to the low-duty cycle of most sonars.
As described in the 2019 MITT DSEIS/OEIS, newer high-duty cycle or
continuous active sonars have more potential to mask vocalizations.
These sonars transmit more frequently (greater than 80 percent duty
cycle) than
[[Page 5809]]
traditional sonars, but at a substantially lower source level. HFAS,
such as pingers that operate at higher repetition rates (e.g., 2-10 kHz
with harmonics up to 19 kHz, 76 to 77 pings per minute) (Culik et al.,
2001), also operate at lower source levels and have a faster
attenuation rates due to the higher frequencies used. These lower
source levels limit the range of impacts, however compared to
traditional sonar systems, individuals close to the source are likely
to experience masking at longer time scales. The frequency range at
which high-duty cycle systems operate overlaps the vocalization
frequency of many mid-frequency cetaceans. Continuous noise at the same
frequency of communicative vocalizations may cause disruptions to
communication, social interactions, acoustically mediated cooperative
behaviors, and important environmental cues. There is also the
potential for the mid-frequency sonar signals to mask important
environmental cues (e.g., predator or conspecific acoustic cues),
possibly affecting survivorship for targeted animals. While there are
currently no available studies of the impacts of high-duty cycle sonars
on marine mammals, masking due to these systems is likely analogous to
masking produced by other continuous sources (e.g., vessel noise and
low-frequency cetaceans), and would likely have similar short-term
consequences, though longer in duration due to the duration of the
masking noise. These may include changes to vocalization amplitude and
frequency (Brumm and Slabbekoorn, 2005; Hotchkin and Parks, 2013) and
behavioral impacts such as avoidance of the area and interruptions to
foraging or other essential behaviors (Gordon et al., 2003). Long-term
consequences could include changes to vocal behavior and vocalization
structure (Foote et al., 2004; Parks et al., 2007), abandonment of
habitat if masking occurs frequently enough to significantly impair
communication (Brumm and Slabbekoorn, 2005), a potential decrease in
survivorship if predator vocalizations are masked (Brumm and
Slabbekoorn, 2005), and a potential decrease in recruitment if masking
interferes with reproductive activities or mother-calf communication
(Gordon et al., 2003).
Masking Due to Vessel Noise
Masking is more likely to occur in the presence of broadband,
relatively continuous noise sources such as vessels. Several studies
have shown decreases in marine mammal communication space and changes
in behavior as a result of the presence of vessel noise. For example,
right whales were observed to shift the frequency content of their
calls upward while reducing the rate of calling in areas of increased
anthropogenic noise (Parks et al., 2007) as well as increasing the
amplitude (intensity) of their calls (Parks, 2009; Parks et al., 2011).
Clark et al. (2009) also observed that right whales communication space
decreased by up to 84 percent in the presence of vessels (Clark et al.,
2009). Cholewiak et al. (2018) also observed loss in communication
space in Stellwagen National Marine Sanctuary for North Atlantic right
whales, fin whales, and humpback whales with increased ambient noise
and shipping noise. Although humpback whales off Australia did not
change the frequency or duration of their vocalizations in the presence
of ship noise, their source levels were lower than expected based on
source level changes to wind noise, potentially indicating some signal
masking (Dunlop, 2016). Multiple delphinid species have also been shown
to increase the minimum or maximum frequencies of their whistles in the
presence of anthropogenic noise and reduced communication space (for
examples see: Holt et al., 2008; Holt et al., 2011; Gervaise et al.,
2012; Williams et al., 2013; Hermannsen et al., 2014; Papale et al.,
2015; Liu et al., 2017).
Behavioral Response/Disturbance
Behavioral responses to sound are highly variable and context-
specific. Many different variables can influence an animal's perception
of and response to (nature and magnitude) an acoustic event. An
animal's prior experience with a sound or sound source affects whether
it is less likely (habituation) or more likely (sensitization) to
respond to certain sounds in the future (animals can also be innately
predisposed to respond to certain sounds in certain ways) (Southall et
al., 2007). Related to the sound itself, the perceived nearness of the
sound, bearing of the sound (approaching vs. retreating), the
similarity of a sound to biologically relevant sounds in the animal's
environment (i.e., calls of predators, prey, or conspecifics), and
familiarity of the sound may affect the way an animal responds to the
sound (Southall et al., 2007, DeRuiter et al., 2013). Individuals (of
different age, gender, reproductive status, etc.) among most
populations will have variable hearing capabilities, and differing
behavioral sensitivities to sounds that will be affected by prior
conditioning, experience, and current activities of those individuals.
Often, specific acoustic features of the sound and contextual variables
(i.e., proximity, duration, or recurrence of the sound or the current
behavior that the marine mammal is engaged in or its prior experience),
as well as entirely separate factors such as the physical presence of a
nearby vessel, may be more relevant to the animal's response than the
received level alone. For example, Goldbogen et al. (2013) demonstrated
that individual behavioral state was critically important in
determining response of blue whales to sonar, noting that some
individuals engaged in deep (>50 m) feeding behavior had greater dive
responses than those in shallow feeding or non-feeding conditions. Some
blue whales in the Goldbogen et al. (2013) study that were engaged in
shallow feeding behavior demonstrated no clear changes in diving or
movement even when received levels (RLs) were high (~160 dB re
1[micro]Pa) for exposures to 3-4 kHz sonar signals, while others showed
a clear response at exposures at lower received levels of sonar and
pseudorandom noise.
Studies by DeRuiter et al. (2012) indicate that variability of
responses to acoustic stimuli depends not only on the species receiving
the sound and the sound source, but also on the social, behavioral, or
environmental contexts of exposure. Another study by DeRuiter et al.
(2013) examined behavioral responses of Cuvier's beaked whales to MF
sonar and found that whales responded strongly at low received levels
(RL of 89-127 dB re 1[micro]Pa) by ceasing normal fluking and
echolocation, swimming rapidly away, and extending both dive duration
and subsequent non-foraging intervals when the sound source was 3.4--
9.5 km away. Importantly, this study also showed that whales exposed to
a similar range of received levels (78-106 dB re 1[micro]Pa) from
distant sonar exercises (118 km away) did not elicit such responses,
suggesting that context may moderate reactions.
Ellison et al. (2012) outlined an approach to assessing the effects
of sound on marine mammals that incorporates contextual-based factors.
The authors recommend considering not just the received level of sound,
but also the activity the animal is engaged in at the time the sound is
received, the nature and novelty of the sound (i.e., is this a new
sound from the animal's perspective), and the distance between the
sound source and the animal. They submit that this ``exposure
context,'' as described, greatly influences the type of behavioral
response exhibited by the animal. Forney et al. (2017) also point out
that an apparent lack of response (e.g., no displacement or avoidance
of a sound source) may not necessarily mean
[[Page 5810]]
there is no cost to the individual or population, as some resources or
habitats may be of such high value that animals may choose to stay,
even when experiencing stress or hearing loss. Forney et al. (2017)
recommend considering both the costs of remaining in an area of noise
exposure such as TTS, PTS, or masking, which could lead to an increased
risk of predation or other threats or a decreased capability to forage,
and the costs of displacement, including potential increased risk of
vessel strike, increased risks of predation or competition for
resources, or decreased habitat suitable for foraging, resting, or
socializing. This sort of contextual information is challenging to
predict with accuracy for ongoing activities that occur over large
spatial and temporal expanses. However, distance is one contextual
factor for which data exist to quantitatively inform a take estimate,
and the method for predicting Level B harassment in this rule does
consider distance to the source. Other factors are often considered
qualitatively in the analysis of the likely consequences of sound
exposure, where supporting information is available.
Friedlaender et al. (2016) provided the first integration of direct
measures of prey distribution and density variables incorporated into
across-individual analyses of behavior responses of blue whales to
sonar, and demonstrated a five-fold increase in the ability to quantify
variability in blue whale diving behavior. These results illustrate
that responses evaluated without such measurements for foraging animals
may be misleading, which again illustrates the context-dependent nature
of the probability of response.
Exposure of marine mammals to sound sources can result in, but is
not limited to, no response or any of the following observable
responses: Increased alertness; orientation or attraction to a sound
source; vocal modifications; cessation of feeding; cessation of social
interaction; alteration of movement or diving behavior; habitat
abandonment (temporary or permanent); and, in severe cases, panic,
flight, stampede, or stranding, potentially resulting in death
(Southall et al., 2007). A review of marine mammal responses to
anthropogenic sound was first conducted by Richardson (1995). More
recent reviews (Nowacek et al., 2007; DeRuiter et al., 2012 and 2013;
Ellison et al., 2012; Gomez et al., 2016) address studies conducted
since 1995 and focused on observations where the received sound level
of the exposed marine mammal(s) was known or could be estimated. Gomez
et al. (2016) conducted a review of the literature considering the
contextual information of exposure in addition to received level and
found that higher received levels were not always associated with more
severe behavioral responses and vice versa. Southall et al. (2016)
states that results demonstrate that some individuals of different
species display clear yet varied responses, some of which have negative
implications, while others appear to tolerate high levels, and that
responses may not be fully predictable with simple acoustic exposure
metrics (e.g., received sound level). Rather, the authors state that
differences among species and individuals along with contextual aspects
of exposure (e.g., behavioral state) appear to affect response
probability. The following subsections provide examples of behavioral
responses that provide an idea of the variability in behavioral
responses that would be expected given the differential sensitivities
of marine mammal species to sound and the wide range of potential
acoustic sources to which a marine mammal may be exposed. Behavioral
responses that could occur for a given sound exposure should be
determined from the literature that is available for each species, or
extrapolated from closely related species when no information exists,
along with contextual factors.
Flight Response
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996). The result of a flight response could range from
brief, temporary exertion and displacement from the area where the
signal provokes flight to, in extreme cases, being a component of
marine mammal strandings associated with sonar activities (Evans and
England, 2001). If marine mammals respond to Navy vessels that are
transmitting active sonar in the same way that they might respond to a
predator, their probability of flight responses should increase when
they perceive that Navy vessels are approaching them directly, because
a direct approach may convey detection and intent to capture (Burger
and Gochfeld, 1981, 1990; Cooper, 1997, 1998). There are limited data
on flight response for marine mammals; however, there are examples of
this response in species on land. For instance, the probability of
flight responses in Dall's sheep Ovis dalli dalli (Frid, 2001), hauled-
out ringed seals Phoca hispida (Born et al., 1999), Pacific brant
(Branta bernicl nigricans), and Canada geese (B. canadensis) increased
as a helicopter or fixed-wing aircraft more directly approached groups
of these animals (Ward et al., 1999). Bald eagles (Haliaeetus
leucocephalus) perched on trees alongside a river were also more likely
to flee from a paddle raft when their perches were closer to the river
or were closer to the ground (Steidl and Anthony, 1996).
Response to Predator
Evidence suggests that at least some marine mammals have the
ability to acoustically identify potential predators. For example,
harbor seals that reside in the coastal waters off British Columbia are
frequently targeted by certain groups of killer whales, but not others.
The seals discriminate between the calls of threatening and non-
threatening killer whales (Deecke et al., 2002), a capability that
should increase survivorship while reducing the energy required for
attending to and responding to all killer whale calls. The occurrence
of masking or hearing impairment provides a means by which marine
mammals may be prevented from responding to the acoustic cues produced
by their predators. Whether or not this is a possibility depends on the
duration of the masking/hearing impairment and the likelihood of
encountering a predator during the time that predator cues are impeded.
Alteration of Diving or Movement
Changes in dive behavior can vary widely. They may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Ng and Leung, 2003; Nowacek et al.; 2004; Goldbogen et
al., 2013a, 2013b). Variations in dive behavior may reflect
interruptions in biologically significant activities (e.g., foraging)
or they may be of little biological significance. Variations in dive
behavior may also expose an animal to potentially harmful conditions
(e.g., increasing the chance of ship-strike) or may serve as an
avoidance response that enhances survivorship. The impact of a
variation in diving resulting from an acoustic exposure depends on what
the animal is doing at the time of the exposure and the type and
magnitude of the response.
[[Page 5811]]
Nowacek et al. (2004) reported disruptions of dive behaviors in
foraging North Atlantic right whales when exposed to an alerting
stimulus, an action, they noted, that could lead to an increased
likelihood of ship strike. However, the whales did not respond to
playbacks of either right whale social sounds or vessel noise,
highlighting the importance of the sound characteristics in producing a
behavioral reaction. Conversely, Indo-Pacific humpback dolphins have
been observed to dive for longer periods of time in areas where vessels
were present and/or approaching (Ng and Leung, 2003). In both of these
studies, the influence of the sound exposure cannot be decoupled from
the physical presence of a surface vessel, thus complicating
interpretations of the relative contribution of each stimulus to the
response. Indeed, the presence of surface vessels, their approach, and
speed of approach, seemed to be significant factors in the response of
the Indo-Pacific humpback dolphins (Ng and Leung, 2003). Low frequency
signals of the Acoustic Thermometry of Ocean Climate (ATOC) sound
source were not found to affect dive times of humpback whales in
Hawaiian waters (Frankel and Clark, 2000) or to overtly affect elephant
seal dives (Costa et al., 2003). They did, however, produce subtle
effects that varied in direction and degree among the individual seals,
illustrating the equivocal nature of behavioral effects and consequent
difficulty in defining and predicting them. Lastly, as noted
previously, DeRuiter et al. (2013) noted that distance from a sound
source may moderate marine mammal reactions in their study of Cuvier's
beaked whales, which showed the whales swimming rapidly and silently
away when a sonar signal was 3.4-9.5 km away while showing no such
reaction to the same signal when the signal was 118 km away even though
the received levels were similar.
Foraging
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.,
2001; Nowacek et al.; 2004; Madsen et al., 2006a; Yazvenko et al.,
2007). A determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
Noise from seismic surveys was not found to impact the feeding
behavior in western grey whales off the coast of Russia (Yazvenko et
al., 2007). Visual tracking, passive acoustic monitoring, and movement
recording tags were used to quantify sperm whale behavior prior to,
during, and following exposure to air gun arrays at received levels in
the range 140-160 dB at distances of 7-13 km, following a phase-in of
sound intensity and full array exposures at 1-13 km (Madsen et al.,
2006a; Miller et al., 2009). Sperm whales did not exhibit horizontal
avoidance behavior at the surface. However, foraging behavior may have
been affected. The sperm whales exhibited 19 percent less vocal (buzz)
rate during full exposure relative to post exposure, and the whale that
was approached most closely had an extended resting period and did not
resume foraging until the air guns had ceased firing. The remaining
whales continued to execute foraging dives throughout exposure;
however, swimming movements during foraging dives were six percent
lower during exposure than control periods (Miller et al., 2009). These
data raise concerns that air gun surveys may impact foraging behavior
in sperm whales, although more data are required to understand whether
the differences were due to exposure or natural variation in sperm
whale behavior (Miller et al., 2009).
Balaenopterid whales exposed to moderate low-frequency signals
similar to the ATOC sound source demonstrated no variation in foraging
activity (Croll et al., 2001), whereas five out of six North Atlantic
right whales exposed to an acoustic alarm interrupted their foraging
dives (Nowacek et al., 2004). Although the received SPLs were similar
in the latter two studies, the frequency, duration, and temporal
pattern of signal presentation were different. These factors, as well
as differences in species sensitivity, are likely contributing factors
to the differential response. Blue whales exposed to mid-frequency
sonar in the Southern California Bight were less likely to produce low
frequency calls usually associated with feeding behavior (Melc[oacute]n
et al., 2012). However, Melco[acute]n et al. (2012) were unable to
determine if suppression of low frequency calls reflected a change in
their feeding performance or abandonment of foraging behavior and
indicated that implications of the documented responses are unknown.
Further, it is not known whether the lower rates of calling actually
indicated a reduction in feeding behavior or social contact since the
study used data from remotely deployed, passive acoustic monitoring
buoys. In contrast, blue whales increased their likelihood of calling
when ship noise was present, and decreased their likelihood of calling
in the presence of explosive noise, although this result was not
statistically significant (Melc[oacute]n et al., 2012). Additionally,
the likelihood of an animal calling decreased with the increased
received level of mid-frequency sonar, beginning at a SPL of
approximately 110-120 dB re 1 [micro]Pa (Melco[acute]n et al., 2012).
Results from the 2010-2011 field season of a behavioral response study
in Southern California waters indicated that, in some cases and at low
received levels, tagged blue whales responded to mid-frequency sonar
but that those responses were mild and there was a quick return to
their baseline activity (Southall et al., 2011; Southall et al., 2012b,
Southall et al., 2019b). Information on or estimates of the energetic
requirements of the individuals and the relationship between prey
availability, foraging effort and success, and the life history stage
of the animal will help better inform a determination of whether
foraging disruptions incur fitness consequences. Surface feeding blue
whales did not show a change in behavior in response to mid-frequency
simulated and real sonar sources with received levels between 90 and
179 dB re 1 [micro]Pa, but deep feeding and non-feeding whales showed
temporary reactions including cessation of feeding, reduced initiation
of deep foraging dives, generalized avoidance responses, and changes to
dive behavior (DeRuiter et al., 2017; Goldbogen et al., 2013b; Sivle et
al., 2015). Goldbogen et al. (2013b) indicate that disruption of
feeding and displacement could impact individual fitness and health.
However, for this to be true, we would have to assume that an
individual whale could not compensate for this lost feeding opportunity
by either immediately feeding at another location, by feeding shortly
after cessation of acoustic exposure, or by feeding at a later time.
There is no indication this is the case, particularly since unconsumed
prey would likely still be available in the environment in most cases
following the cessation of acoustic exposure.
[[Page 5812]]
Similarly, while the rates of foraging lunges decrease in humpback
whales due to sonar exposure, there was variability in the response
across individuals, with one animal ceasing to forage completely and
another animal starting to forage during the exposure (Sivle et al.,
2016). In addition, almost half of the animals that avoided were
foraging before the exposure but the others were not; the animals that
avoided while not feeding responded at a slightly lower received level
and greater distance than those that were feeding (Wensveen et al.,
2017). These findings indicate that the behavioral state of the animal
plays a role in the type and severity of a behavioral response. In
fact, when the prey field was mapped and used as a covariate in similar
models looking for a response in the same blue whales, the response in
deep-feeding behavior by blue whales was even more apparent,
reinforcing the need for contextual variables to be included when
assessing behavioral responses (Friedlaender et al., 2016).
Breathing
Respiration naturally varies with different behaviors and
variations in respiration rate as a function of acoustic exposure can
be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Mean exhalation rates of gray whales at rest and while
diving were found to be unaffected by seismic surveys conducted
adjacent to the whale feeding grounds (Gailey et al., 2007). Studies
with captive harbor porpoises showed increased respiration rates upon
introduction of acoustic alarms (Kastelein et al., 2001; Kastelein et
al., 2006a) and emissions for underwater data transmission (Kastelein
et al., 2005). However, exposure of the same acoustic alarm to a
striped dolphin under the same conditions did not elicit a response
(Kastelein et al., 2006a), again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure.
Social Relationships
Social interactions between mammals can be affected by noise via
the disruption of communication signals or by the displacement of
individuals. Disruption of social relationships therefore depends on
the disruption of other behaviors (e.g., avoidance, masking, etc.).
Sperm whales responded to military sonar, apparently from a submarine,
by dispersing from social aggregations, moving away from the sound
source, remaining relatively silent, and becoming difficult to approach
(Watkins et al., 1985). In contrast, sperm whales in the Mediterranean
that were exposed to submarine sonar continued calling (J. Gordon pers.
comm. cited in Richardson et al., 1995). Long-finned pilot whales
exposed to three types of disturbance--playbacks of killer whale
sounds, naval sonar exposure, and tagging--resulted in increased group
sizes (Visser et al., 2016). In response to sonar, pilot whales also
spent more time at the surface with other members of the group (Visser
et al., 2016). However, social disruptions must be considered in
context of the relationships that are affected. While some disruptions
may not have deleterious effects, others, such as long-term or repeated
disruptions of mother/calf pairs or interruption of mating behaviors,
have the potential to affect the growth and survival or reproductive
effort/success of individuals.
Vocalizations (Also See Auditory Masking Section)
Vocal changes in response to anthropogenic noise can occur across
the repertoire of sound production modes used by marine mammals, such
as whistling, echolocation click production, calling, and singing.
Changes in vocalization behavior may result in response to
anthropogenic noise can occur for any of these modes and may result
from a need to compete with an increase in background noise or may
reflect an increased vigilance or a startle response. For example, in
the presence of potentially masking signals (low-frequency active
sonar), humpback whales have been observed to increase the length of
their songs (Miller et al., 2000; Fristrup et al., 2003). A similar
compensatory effect for the presence of low-frequency vessel noise has
been suggested for right whales; right whales have been observed to
shift the frequency content of their calls upward while reducing the
rate of calling in areas of increased anthropogenic noise (Parks et
al., 2007; Roland et al., 2012). Killer whales off the northwestern
coast of the United States have been observed to increase the duration
of primary calls once a threshold in observing vessel density (e.g.,
whale watching) was reached, which has been suggested as a response to
increased masking noise produced by the vessels (Foote et al., 2004;
NOAA, 2014b). In contrast, both sperm and pilot whales potentially
ceased sound production during the Heard Island feasibility test
(Bowles et al., 1994), although it cannot be absolutely determined
whether the inability to acoustically detect the animals was due to the
cessation of sound production or the displacement of animals from the
area.
Cerchio et al. (2014) used passive acoustic monitoring to document
the presence of singing humpback whales off the coast of northern
Angola and to opportunistically test for the effect of seismic survey
activity on the number of singing whales. Two recording units were
deployed between March and December 2008 in the offshore environment;
numbers of singers were counted every hour. Generalized Additive Mixed
Models were used to assess the effect of survey day (seasonality), hour
(diel variation), moon phase, and received levels of noise (measured
from a single pulse during each ten-minute sampled period) on singer
number. The number of singers significantly decreased with increasing
received level of noise, suggesting that humpback whale communication
was disrupted to some extent by the survey activity.
Castellote et al. (2012) reported acoustic and behavioral changes
by fin whales in response to shipping and air gun noise. Acoustic
features of fin whale song notes recorded in the Mediterranean Sea and
northeast Atlantic Ocean were compared for areas with different
shipping noise levels and traffic intensities and during an air gun
survey. During the first 72 hours of the survey, a steady decrease in
song received levels and bearings to singers indicated that whales
moved away from the acoustic source and out of a Navy study area. This
displacement persisted for a time period well beyond the 10-day
duration of air gun activity, providing evidence that fin whales may
avoid an area for an extended period in the presence of increased
noise. The authors hypothesize that fin whale acoustic communication is
modified to compensate for increased background noise and that a
sensitization process may play a role in the observed temporary
displacement.
Seismic pulses at average received levels of 131 dB re 1
micropascal squared per second ([micro]Pa2-s) caused blue whales to
increase call production (Di Iorio and Clark, 2010). In contrast,
McDonald et al. (1995) tracked a blue whale with seafloor seismometers
and reported that it stopped vocalizing and changed its travel
direction at a range of 10 km from the seismic vessel (estimated
received level 143 dB re 1 [micro]Pa peak-to-peak). Blackwell et al.
(2013) found that bowhead whale call rates dropped significantly at
onset of
[[Page 5813]]
air gun use at sites with a median distance of 41-45 km from the
survey. Blackwell et al. (2015) expanded this analysis to show that
whales actually increased calling rates as soon as air gun signals were
detectable before ultimately decreasing calling rates at higher
received levels (i.e., 10-minute cumulative sound exposure level (cSEL)
of ~127 dB). Overall, these results suggest that bowhead whales may
adjust their vocal output in an effort to compensate for noise before
ceasing vocalization effort and ultimately deflecting from the acoustic
source (Blackwell et al., 2013, 2015). Captive bottlenose dolphins
sometimes vocalized after an exposure to impulse sound from a seismic
water gun (Finneran et al., 2010a). These studies demonstrate that even
low levels of noise received far from the noise source can induce
changes in vocalization and/or behavioral responses.
Avoidance
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors. Richardson et al. (1995) noted that avoidance reactions are
the most obvious manifestations of disturbance in marine mammals.
Avoidance is qualitatively different from the flight response, but also
differs in the magnitude of the response (i.e., directed movement, rate
of travel, etc.). Oftentimes avoidance is temporary, and animals return
to the area once the noise has ceased. Acute avoidance responses have
been observed in captive porpoises and pinnipeds exposed to a number of
different sound sources (Kastelein et al., 2001; Finneran et al., 2003;
Kastelein et al., 2006a; Kastelein et al., 2006b). Short-term avoidance
of seismic surveys, low frequency emissions, and acoustic deterrents
have also been noted in wild populations of odontocetes (Bowles et al.,
1994; Goold, 1996; 1998; Stone et al., 2000; Morton and Symonds, 2002)
and to some extent in mysticetes (Gailey et al., 2007). Longer-term
displacement is possible, however, which may lead to changes in
abundance or distribution patterns of the affected species in the
affected region if habituation to the presence of the sound does not
occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann et
al., 2006). Longer term or repetitive/chronic displacement for some
dolphin groups and for manatees has been suggested to be due to the
presence of chronic vessel noise (Haviland-Howell et al., 2007; Miksis-
Olds et al., 2007). Gray whales have been reported deflecting from
customary migratory paths in order to avoid noise from air gun surveys
(Malme et al., 1984). Humpback whales showed avoidance behavior in the
presence of an active air gun array during observational studies and
controlled exposure experiments in western Australia (McCauley et al.,
2000a).
Forney et al. (2017) detailed the potential effects of noise on
marine mammal populations with high site fidelity, including
displacement and auditory masking, noting that a lack of observed
response does not imply absence of fitness costs and that apparent
tolerance of disturbance may have population-level impacts that are
less obvious and difficult to document. Avoidance of overlap between
disturbing noise and areas and/or times of particular importance for
sensitive species may be critical to avoiding population-level impacts
because (particularly for animals with high site fidelity) there may be
a strong motivation to remain in the area despite negative impacts.
Forney et al. (2017) stated that, for these animals, remaining in a
disturbed area may reflect a lack of alternatives rather than a lack of
effects. The authors discuss several case studies, including western
Pacific gray whales, which are a small population of mysticetes
believed to be adversely affected by oil and gas development off
Sakhalin Island, Russia (Weller et al., 2002; Reeves et al., 2005).
Western gray whales display a high degree of interannual site fidelity
to the area for foraging purposes, and observations in the area during
air gun surveys has shown the potential for harm caused by displacement
from such an important area (Weller et al., 2006; Johnson et al.,
2007). Forney et al. (2017) also discuss beaked whales, noting that
anthropogenic effects in areas where they are resident could cause
severe biological consequences, in part because displacement may
adversely affect foraging rates, reproduction, or health, while an
overriding instinct to remain could lead to more severe acute effects.
In 1998, the Navy conducted a Low Frequency Sonar Scientific
Research Program (LFS SRP) specifically to study behavioral responses
of several species of marine mammals to exposure to LF sound, including
one phase that focused on the behavior of gray whales to low frequency
sound signals. The objective of this phase of the LFS SRP was to
determine whether migrating gray whales respond more strongly to
received levels, sound gradient, or distance from the source, and to
compare whale avoidance responses to an LF source in the center of the
migration corridor versus in the offshore portion of the migration
corridor. A single source was used to broadcast LFA sonar sounds at
received levels of 170-178 dB re 1[micro]Pa. The Navy reported that the
whales showed some avoidance responses when the source was moored one
mile (1.8 km) offshore, and located within the migration path, but the
whales returned to their migration path when they were a few kilometers
beyond the source. When the source was moored two miles (3.7 km)
offshore, responses were much less even when the source level was
increased to achieve the same received levels in the middle of the
migration corridor as whales received when the source was located
within the migration corridor (Clark et al., 1999). In addition, the
researchers noted that the offshore whales did not seem to avoid the
louder offshore source.
Also during the LFS SRP, researchers sighted numerous odontocete
and pinniped species in the vicinity of the sound exposure tests with
LFA sonar. The MF and HF hearing specialists present in California and
Hawaii showed no immediately obvious responses or changes in sighting
rates as a function of source conditions. Consequently, the researchers
concluded that none of these species had any obvious behavioral
reaction to LFA sonar signals at received levels similar to those that
produced only minor short-term behavioral responses in the baleen
whales (i.e., LF hearing specialists). Thus, for odontocetes, the
chances of injury and/or significant behavioral responses to LFA sonar
would be low given the MF/HF specialists' observed lack of response to
LFA sounds during the LFS SRP and due to the MF/HF frequencies to which
these animals are adapted to hear (Clark and Southall, 2009).
Maybaum (1993) conducted sound playback experiments to assess the
effects of MFAS on humpback whales in Hawaiian waters. Specifically,
she exposed focal pods to sounds of a 3.3-kHz sonar pulse, a sonar
frequency sweep from 3.1 to 3.6 kHz, and a control (blank) tape while
monitoring behavior, movement, and underwater vocalizations. The two
types of sonar signals differed in their effects on the humpback
whales, but both resulted in avoidance behavior. The whales responded
to the pulse by increasing their distance from the sound source and
responded to the frequency sweep by increasing their swimming speeds
and track linearity. In the Caribbean, sperm whales avoided exposure to
mid-frequency submarine sonar pulses, in the range of 1000 Hz to 10,000
Hz (IWC, 2005).
[[Page 5814]]
Kvadsheim et al. (2007) conducted a controlled exposure experiment
in which killer whales fitted with D-tags were exposed to mid-frequency
active sonar (Source A: A 1.0 second upsweep 209 dB @1-2 kHz every 10
seconds for 10 minutes; Source B: With a 1.0 second upsweep 197 dB @6-7
kHz every 10 seconds for 10 minutes). When exposed to Source A, a
tagged whale and the group it was traveling with did not appear to
avoid the source. When exposed to Source B, the tagged whales along
with other whales that had been carousel feeding, where killer whales
cooperatively herd fish schools into a tight ball towards the surface
and feed on the fish which have been stunned by tailslaps, and
subsurface feeding (Simila, 1997) ceased feeding during the approach of
the sonar and moved rapidly away from the source. When exposed to
Source B, Kvadsheim et al. (2007) reported that a tagged killer whale
seemed to try to avoid further exposure to the sound field by the
following behaviors: Immediately swimming away (horizontally) from the
source of the sound; engaging in a series of erratic and frequently
deep dives that seemed to take it below the sound field; or swimming
away while engaged in a series of erratic and frequently deep dives.
Although the sample sizes in this study are too small to support
statistical analysis, the behavioral responses of the killer whales
were consistent with the results of other studies.
Southall et al. (2007) reviewed the available literature on marine
mammal hearing and physiological and behavioral responses to human-made
sound with the goal of proposing exposure criteria for certain effects.
This peer-reviewed compilation of literature is very valuable, though
Southall et al. (2007) note that not all data are equal, some have poor
statistical power, insufficient controls, and/or limited information on
received levels, background noise, and other potentially important
contextual variables. Such data were reviewed and sometimes used for
qualitative illustration, but no quantitative criteria were recommended
for behavioral responses. All of the studies considered, however,
contain an estimate of the received sound level when the animal
exhibited the indicated response.
In the Southall et al. (2007) publication, for the purposes of
analyzing responses of marine mammals to anthropogenic sound and
developing criteria, the authors differentiate between single pulse
sounds, multiple pulse sounds, and non-pulse sounds. LFAS/MFAS/HFAS are
considered non-pulse sounds. Southall et al. (2007) summarize the
studies associated with low-frequency, mid-frequency, and high-
frequency cetacean and pinniped responses to non-pulse sounds, based
strictly on received level, in Appendix C of their article (referenced
and summarized in the following paragraphs).
The studies that address responses of low-frequency cetaceans to
non-pulse sounds include data gathered in the field and related to
several types of sound sources (of varying similarity to MFAS/HFAS)
including: Vessel noise, drilling and machinery playback, low-frequency
M-sequences (sine wave with multiple phase reversals) playback,
tactical low-frequency active sonar playback, drill ships, Acoustic
Thermometry of Ocean Climate (ATOC) source, and non-pulse playbacks.
These studies generally indicate no (or very limited) responses to
received levels in the 90 to 120 dB re: 1 [micro]Pa range and an
increasing likelihood of avoidance and other behavioral effects in the
120 to 160 dB re: 1 [micro]Pa range. As mentioned earlier, though,
contextual variables play a very important role in the reported
responses and the severity of effects are not linear when compared to
received level. Also, few of the laboratory or field datasets had
common conditions, behavioral contexts, or sound sources, so it is not
surprising that responses differ.
The studies that address responses of mid-frequency cetaceans to
non-pulse sounds include data gathered both in the field and the
laboratory and related to several different sound sources (of varying
similarity to MFAS/HFAS) including: Pingers, drilling playbacks, ship
and ice-breaking noise, vessel noise, Acoustic Harassment Devices
(AHDs), Acoustic Deterrent Devices (ADDs), MFAS, and non-pulse bands
and tones. Southall et al. (2007) were unable to come to a clear
conclusion regarding the results of these studies. In some cases,
animals in the field showed significant responses to received levels
between 90 and 120 dB re: 1 [micro]Pa, while in other cases these
responses were not seen in the 120 to 150 dB re: 1 [micro]Pa range. The
disparity in results was likely due to contextual variation and the
differences between the results in the field and laboratory data
(animals typically responded at lower levels in the field).
The studies that address responses of high-frequency cetaceans to
non-pulse sounds include data gathered both in the field and the
laboratory and related to several different sound sources (of varying
similarity to MFAS/HFAS) including: pingers, AHDs, and various
laboratory non-pulse sounds. All of these data were collected from
harbor porpoises. Southall et al. (2007) concluded that the existing
data indicate that harbor porpoises are likely sensitive to a wide
range of anthropogenic sounds at low received levels (~ 90 to 120 dB
re: 1 [micro]Pa), at least for initial exposures. All recorded
exposures above 140 dB re: 1 [micro]Pa induced profound and sustained
avoidance behavior in wild harbor porpoises (Southall et al., 2007).
Rapid habituation was noted in some but not all studies. There are no
data to indicate whether other high frequency cetaceans are as
sensitive to anthropogenic sound as harbor porpoises.
The studies that address the responses of pinnipeds in water to
non-impulsive sounds include data gathered both in the field and the
laboratory and related to several different sound sources including:
AHDs, ATOC, various non-pulse sounds used in underwater data
communication, underwater drilling, and construction noise. Few studies
exist with enough information to include them in the analysis. The
limited data suggested that exposures to non-pulse sounds between 90
and 140 dB re: 1 [micro]Pa generally do not result in strong behavioral
responses in pinnipeds in water, but no data exist at higher received
levels.
In 2007, the first in a series of behavioral response studies (BRS)
on deep diving odontocetes conducted by NMFS, Navy, and other
scientists showed one Blainville's beaked whale responding to an MFAS
playback. Tyack et al. (2011) indicates that the playback began when
the tagged beaked whale was vocalizing at depth (at the deepest part of
a typical feeding dive), following a previous control with no sound
exposure. The whale appeared to stop clicking significantly earlier
than usual, when exposed to MF signals in the 130-140 dB (rms) received
level range. After a few more minutes of the playback, when the
received level reached a maximum of 140-150 dB, the whale ascended on
the slow side of normal ascent rates with a longer than normal ascent,
at which point the exposure was terminated. The results are from a
single experiment and a greater sample size is needed before robust and
definitive conclusions can be drawn. Tyack et al. (2011) also indicates
that Blainville's beaked whales appear to be sensitive to noise at
levels well below expected TTS (~160 dB re1[micro]Pa). This sensitivity
was manifested by an adaptive movement away from a sound source. This
response was observed irrespective of whether the signal transmitted
was within the band width of MFAS, which suggests that beaked whales
may not
[[Page 5815]]
respond to the specific sound signatures. Instead, they may be
sensitive to any pulsed sound from a point source in this frequency
range of the MF active sonar transmission. The response to such stimuli
appears to involve the beaked whale increasing the distance between it
and the sound source. Overall the results from the 2007-2008 study
showed a change in diving behavior of the Blainville's beaked whale to
playback of MFAS and predator sounds (Boyd et al., 2008; Southall et
al., 2009; Tyack et al., 2011).
Stimpert et al. (2014) tagged a Baird's beaked whale, which was
subsequently exposed to simulated MFAS. Received levels of sonar on the
tag increased to a maximum of 138 dB re 1[mu]Pa, which occurred during
the first exposure dive. Some sonar received levels could not be
measured due to flow noise and surface noise on the tag.
Reaction to mid-frequency sounds included premature cessation of
clicking and termination of a foraging dive, and a slower ascent rate
to the surface. Results from a similar behavioral response study in
southern California waters have been presented for the 2010-2011 field
season (Southall et al., 2011; DeRuiter et al., 2013b). DeRuiter et al.
(2013b) presented results from two Cuvier's beaked whales that were
tagged and exposed to simulated MFAS during the 2010 and 2011 field
seasons of the southern California behavioral response study. The 2011
whale was also incidentally exposed to MFAS from a distant naval
exercise. Received levels from the MFAS signals from the controlled and
incidental exposures were calculated as 84-144 and 78-106 dB re 1
[micro]Pa rms, respectively. Both whales showed responses to the
controlled exposures, ranging from initial orientation changes to
avoidance responses characterized by energetic fluking and swimming
away from the source. However, the authors did not detect similar
responses to incidental exposure to distant naval sonar exercises at
comparable received levels, indicating that context of the exposures
(e.g., source proximity, controlled source ramp-up) may have been a
significant factor. Specifically, this result suggests that caution is
needed when using marine mammal response data collected from smaller,
nearer sound sources to predict at what received levels animals may
respond to larger sound sources that are significantly farther away--as
the distance of the source appears to be an important contextual
variable and animals may be less responsive to sources at notably
greater distances. Cuvier's beaked whale responses suggested particular
sensitivity to sound exposure as consistent with results for
Blainville's beaked whale. Similarly, beaked whales exposed to sonar
during British training exercises stopped foraging (DSTL, 2007), and
preliminary results of controlled playback of sonar may indicate
feeding/foraging disruption of killer whales and sperm whales (Miller
et al., 2011).
In the 2007-2008 Bahamas study, playback sounds of a potential
predator--a killer whale--resulted in a similar but more pronounced
reaction, which included longer inter-dive intervals and a sustained
straight-line departure of more than 20 km from the area (Boyd et al.,
2008; Southall et al., 2009; Tyack et al., 2011). The authors noted,
however, that the magnified reaction to the predator sounds could
represent a cumulative effect of exposure to the two sound types since
killer whale playback began approximately two hours after MF source
playback. Pilot whales and killer whales off Norway also exhibited
horizontal avoidance of a transducer with outputs in the mid-frequency
range (signals in the 1-2 kHz and 6-7 kHz ranges) (Miller et al.,
2011). Additionally, separation of a calf from its group during
exposure to MFAS playback was observed on one occasion (Miller et al.,
2011, 2012). Miller et al. (2012) noted that this single observed
mother-calf separation was unusual for several reasons, including the
fact that the experiment was conducted in an unusually narrow fjord
roughly one km wide and that the sonar exposure was started unusually
close to the pod including the calf. Both of these factors could have
contributed to calf separation. In contrast, preliminary analyses
suggest that none of the pilot whales or false killer whales in the
Bahamas showed an avoidance response to controlled exposure playbacks
(Southall et al., 2009).
In the 2010 BRS study, researchers again used controlled exposure
experiments to carefully measure behavioral responses of individual
animals to sound exposures of MF active sonar and pseudo-random noise.
For each sound type, some exposures were conducted when animals were in
a surface feeding (approximately 164 ft (50 m) or less) and/or
socializing behavioral state and others while animals were in a deep
feeding (greater than 164 ft (50 m)) and/or traveling mode. The
researchers conducted the largest number of controlled exposure
experiments on blue whales (n = 19) and of these, 11 controlled
exposure experiments involved exposure to the MF active sonar sound
type. For the majority of controlled exposure experiment transmissions
of either sound type, they noted few obvious behavioral responses
detected either by the visual observers or on initial inspection of the
tag data. The researchers observed that throughout the controlled
exposure experiment transmissions, up to the highest received sound
level (absolute RMS value approximately 160 dB re: 1[mu]Pa with signal-
to-noise ratio values over 60 dB), two blue whales continued surface
feeding behavior and remained at a range of around 3,820 ft (1,000 m)
from the sound source (Southall et al., 2011). In contrast, another
blue whale (later in the day and greater than 11.5 mi (18.5 km; 10 NM)
from the first controlled exposure experiment location) exposed to the
same stimulus (MFA) while engaged in a deep feeding/travel state
exhibited a different response. In that case, the blue whale responded
almost immediately following the start of sound transmissions when
received sounds were just above ambient background levels (Southall et
al., 2011). The authors note that this kind of temporary avoidance
behavior was not evident in any of the nine controlled exposure
experiments involving blue whales engaged in surface feeding or social
behaviors, but was observed in three of the ten controlled exposure
experiments for blue whales in deep feeding/travel behavioral modes
(one involving MFA sonar; two involving pseudo-random noise) (Southall
et al., 2011). The results of this study, as well as the results of the
DeRuiter et al. (2013) study of Cuvier's beaked whales discussed above,
further illustrate the importance of behavioral context in
understanding and predicting behavioral responses.
Through analysis of the behavioral response studies, a preliminary
overarching effect of greater sensitivity to all anthropogenic
exposures was seen in beaked whales compared to the other odontocetes
studied (Southall et al., 2009). Therefore, recent studies have focused
specifically on beaked whale responses to active sonar transmissions or
controlled exposure playback of simulated sonar on various military
ranges (Defence Science and Technology Laboratory, 2007; Claridge and
Durban, 2009; Moretti et al., 2009; McCarthy et al., 2011; Miller et
al., 2012; Southall et al., 2011, 2012a, 2012b, 2013, 2014; Tyack et
al., 2011). In the Bahamas, Blainville's beaked whales located on the
instrumented range will move off-range during sonar use and return only
after the sonar transmissions have stopped, sometimes
[[Page 5816]]
taking several days to do so (Claridge and Durban 2009; Moretti et al.,
2009; McCarthy et al., 2011; Tyack et al., 2011). Moretti et al. (2014)
used recordings from seafloor-mounted hydrophones at the Atlantic
Undersea Test and Evaluation Center (AUTEC) to analyze the probability
of Blainsville's beaked whale dives before, during, and after Navy
sonar exercises. Southall et al. (2016) indicates that results from
Tyack et al. (2011), Miller et al. (2015), Stimpert et al. (2014), and
DeRuiter et al. (2013) beaked whale studies demonstrate clear, strong,
and pronounced but varied behavioral changes including avoidance with
associated energetic swimming and cessation of individual foraging
dives at quite low received levels (~100 to 135 dB re 1Pa) for
exposures to simulated or active MF military sonars (1 to 8 kHz) with
sound sources approximately 2 to 5 km away. Similar responses by beaked
whales to sonar have been documented by Stimpert et al., 2014, Falcone
et al., 2017, DiMarzio et al., 2018, and Joyce et al., 2019. However,
there are a number of variables influencing response or non-response
include source distance (close vs. far), received sound levels, and
other contextual variables such as other sound sources (e.g., vessels,
etc.) (Manzano-Roth et al., 2016, Falcone et al., 2017, Harris et al.,
2018). Wensveen et al. (2019) found northern bottlenose whales to avoid
sonar out to distances of 28 km, but these distances are well in line
with those observed on Navy ranges (Manzano-Roth et al., 2016; Joyce et
al., 2019) where the animals return once the sonar has ceased.
Furthermore, beaked whales have also shown response to other non-sonar
anthropogenic sounds such as commercial shipping and echosounders (Soto
et al., 2006, Pirotta et al., 2012, Cholewiak et al., 2017). Pirotta et
al. (2012) documented broadband ship noise causing a significant change
in beaked whale behavior up to at least 5.2 kilometers away from the
vessel. Even though beaked whales appear to be sensitive to
anthropogenic sounds, the level of response at the population level
does not appear to be significant based on over a decade of research at
two heavily used Navy training areas in the Pacific (Falcone et al.,
2012, Schorr et al., 2014, DiMarzio et al., 2018, Schorr et al., 2019).
With the exception of seasonal patterns, DiMarzio et al. (2018) did not
detect any changes in annual Cuvier's beaked whale abundance estimates
in Southern California derived from passive acoustic echolocation
detections over nine years (2010-2018). Similar results for
Blainville's beaked whales abundance estimates over several years was
documented in Hawaii (Henderson et al., 2016;, DiMarzio et al., 2018).
Visually, there have been documented repeated sightings in southern
California of the same individual Cuvier's beaked whales over 10 years,
sightings of mother-calf pairs, and recently sightings of the same
mothers with their second calf (Falcone et al., 2012; Schorr et al.,
2014; Schorr et al., 2019; Schorr, unpublished data).
Baleen whales have shown a variety of responses to impulse sound
sources, including avoidance, reduced surface intervals, altered
swimming behavior, and changes in vocalization rates (Richardson et
al., 1995; Gordon et al., 2003; Southall, 2007). While most bowhead
whales did not show active avoidance until within 8 km of seismic
vessels (Richardson et al., 1995), some whales avoided vessels by more
than 20 km at received levels as low as 120 dB re 1 [micro]Pa rms.
Additionally, Malme et al. (1988) observed clear changes in diving and
respiration patterns in bowheads at ranges up to 73 km from seismic
vessels, with received levels as low as 125 dB re 1 [micro]Pa.
Gray whales migrating along the U.S. west coast showed avoidance
responses to seismic vessels by 10 percent of animals at 164 dB re 1
[micro]Pa, and by 90 percent of animals at 190 dB re 1 [micro]Pa, with
similar results for whales in the Bering Sea (Malme, 1986; 1988). In
contrast, noise from seismic surveys was not found to impact feeding
behavior or exhalation rates while resting or diving in western gray
whales off the coast of Russia (Yazvenko et al., 2007; Gailey et al.,
2007).
Humpback whales showed avoidance behavior at ranges of five to
eight km from a seismic array during observational studies and
controlled exposure experiments in western Australia (McCauley, 1998;
Todd et al., 1996). Todd et al. (1996) found no clear short-term
behavioral responses by foraging humpbacks to explosions associated
with construction operations in Newfoundland, but did see a trend of
increased rates of net entanglement and a shift to a higher incidence
of net entanglement closer to the noise source.
The strongest baleen whale response in any behavioral response
study was observed in a minke whale in the 3S2 study, which responded
at 146 dB re 1 [micro]Pa by strongly avoiding the sound source
(Kvadsheim et al., 2017; Sivle et al., 2015). Although the minke whale
increased its swim speed, directional movement, and respiration rate,
none of these were greater than rates observed in baseline behavior,
and its dive behavior remained similar to baseline dives. A minke whale
tagged in the Southern California behavioral response study also
responded by increasing its directional movement, but maintained its
speed and dive patterns, and so did not demonstrate as strong of a
response (Kvadsheim et al., 2017). In addition, the 3S2 minke whale
demonstrated some of the same avoidance behavior during the controlled
ship approach with no sonar, indicating at least some of the response
was to the vessel (Kvadsheim et al., 2017). Martin et al. (2015) found
that the density of calling minke whales was reduced during periods of
Navy training involving sonar relative to the periods before training,
and increased again in the days after training was completed. The
responses of individual whales could not be assessed, so in this case
it is unknown whether the decrease in calling animals indicated that
the animals left the range, or simply ceased calling. Similarly, minke
whale detections made using Marine Acoustic Recording Instruments off
Jacksonville, FL, were reduced or ceased altogether during periods of
sonar use (Simeone et al., 2015; U.S. Department of the Navy, 2013b),
especially with an increased ping rate (Charif et al., 2015).
Orientation
A shift in an animal's resting state or an attentional change via
an orienting response represent behaviors that would be considered mild
disruptions if occurring alone. As previously mentioned, the responses
may co-occur with other behaviors; for instance, an animal may
initially orient toward a sound source, and then move away from it.
Thus, any orienting response should be considered in context of other
reactions that may occur.
Continued Pre-Disturbance Behavior and Habituation
Under some circumstances, some of the individual marine mammals
that are exposed to active sonar transmissions will continue their
normal behavioral activities. In other circumstances, individual
animals will respond to sonar transmissions at lower received levels
and move to avoid additional exposure or exposures at higher received
levels (Richardson et al., 1995).
It is difficult to distinguish between animals that continue their
pre-disturbance behavior without stress responses, animals that
continue their behavior but experience stress responses (that is,
animals that cope with disturbance), and animals that habituate to
disturbance (that is, they may have experienced low-level stress
responses initially, but those responses abated
[[Page 5817]]
over time). Watkins (1986) reviewed data on the behavioral reactions of
fin, humpback, right, and minke whales that were exposed to continuous,
broadband low-frequency shipping and industrial noise in Cape Cod Bay.
He concluded that underwater sound was the primary cause of behavioral
reactions in these species of whales and that the whales responded
behaviorally to acoustic stimuli within their respective hearing
ranges. Watkins also noted that whales showed the strongest behavioral
reactions to sounds in the 15 Hz to 28 kHz range, although negative
reactions (avoidance, interruptions in vocalizations, etc.) were
generally associated with sounds that were either unexpected, too loud,
suddenly louder or different, or perceived as being associated with a
potential threat (such as an approaching ship on a collision course).
In particular, whales seemed to react negatively when they were within
100 m of the source or when received levels increased suddenly in
excess of 12 dB relative to ambient sounds. At other times, the whales
ignored the source of the signal and all four species habituated to
these sounds. Nevertheless, Watkins concluded that whales ignored most
sounds in the background of ambient noise, including sounds from
distant human activities even though these sounds may have had
considerable energies at frequencies well within the whales' range of
hearing. Further, he noted that of the whales observed, fin whales were
the most sensitive of the four species, followed by humpback whales;
right whales were the least likely to be disturbed and generally did
not react to low-amplitude engine noise. By the end of his period of
study, Watkins (1986) concluded that fin and humpback whales had
generally habituated to the continuous and broad-band noise of Cape Cod
Bay while right whales did not appear to change their response. As
mentioned above, animals that habituate to a particular disturbance may
have experienced low-level stress responses initially, but those
responses abated over time. In most cases, this likely means a lessened
immediate potential effect from a disturbance. However, there is cause
for concern where the habituation occurs in a potentially more harmful
situation. For example, animals may become more vulnerable to vessel
strikes once they habituate to vessel traffic (Swingle et al., 1993;
Wiley et al., 1995).
Aicken et al. (2005) monitored the behavioral responses of marine
mammals to a new low-frequency active sonar system used by the British
Navy (the United States Navy considers this to be a mid-frequency
source as it operates at frequencies greater than 1,000 Hz). During
those trials, fin whales, sperm whales, Sowerby's beaked whales, long-
finned pilot whales, Atlantic white-sided dolphins, and common
bottlenose dolphins were observed and their vocalizations were
recorded. These monitoring studies detected no evidence of behavioral
responses that the investigators could attribute to exposure to the
low-frequency active sonar during these trials.
Explosive Sources
Underwater explosive detonations send a shock wave and sound energy
through the water and can release gaseous by-products, create an
oscillating bubble, or cause a plume of water to shoot up from the
water surface. The shock wave and accompanying noise are of most
concern to marine animals. Depending on the intensity of the shock wave
and size, location, and depth of the animal, an animal can be injured,
killed, suffer non-lethal physical effects, experience hearing related
effects with or without behavioral responses, or exhibit temporary
behavioral responses or tolerance from hearing the blast sound.
Generally, exposures to higher levels of impulse and pressure levels
would result in greater impacts to an individual animal.
Injuries resulting from a shock wave take place at boundaries
between tissues of different densities. Different velocities are
imparted to tissues of different densities, and this can lead to their
physical disruption. Blast effects are greatest at the gas-liquid
interface (Landsberg, 2000). Gas-containing organs, particularly the
lungs and gastrointestinal tract, are especially susceptible (Goertner,
1982; Hill, 1978; Yelverton et al., 1973). Intestinal walls can bruise
or rupture, with subsequent hemorrhage and escape of gut contents into
the body cavity. Less severe gastrointestinal tract injuries include
contusions, petechiae (small red or purple spots caused by bleeding in
the skin), and slight hemorrhaging (Yelverton et al., 1973).
Because the ears are the most sensitive to pressure, they are the
organs most sensitive to injury (Ketten, 2000). Sound-related damage
associated with sound energy from detonations can be theoretically
distinct from injury from the shock wave, particularly farther from the
explosion. If a noise is audible to an animal, it has the potential to
damage the animal's hearing by causing decreased sensitivity (Ketten,
1995). Lethal impacts are those that result in immediate death or
serious debilitation in or near an intense source and are not,
technically, pure acoustic trauma (Ketten, 1995). Sublethal impacts
include hearing loss, which is caused by exposures to perceptible
sounds. Severe damage (from the shock wave) to the ears includes
tympanic membrane rupture, fracture of the ossicles, damage to the
cochlea, hemorrhage, and cerebrospinal fluid leakage into the middle
ear. Moderate injury implies partial hearing loss due to tympanic
membrane rupture and blood in the middle ear. Permanent hearing loss
also can occur when the hair cells are damaged by one very loud event,
as well as by prolonged exposure to a loud noise or chronic exposure to
noise. The level of impact from blasts depends on both an animal's
location and, at outer zones, on its sensitivity to the residual noise
(Ketten, 1995).
Further Potential Effects of Behavioral Disturbance on Marine Mammal
Fitness
The different ways that marine mammals respond to sound are
sometimes indicators of the ultimate effect that exposure to a given
stimulus will have on the well-being (survival, reproduction, etc.) of
an animal. There are few quantitative marine mammal data relating the
exposure of marine mammals to sound to effects on reproduction or
survival, though data exists for terrestrial species to which we can
draw comparisons for marine mammals. Several authors have reported that
disturbance stimuli may cause animals to abandon nesting and foraging
sites (Sutherland and Crockford, 1993); may cause animals to increase
their activity levels and suffer premature deaths or reduced
reproductive success when their energy expenditures exceed their energy
budgets (Daan et al., 1996; Feare, 1976; Mullner et al., 2004); or may
cause animals to experience higher predation rates when they adopt
risk-prone foraging or migratory strategies (Frid and Dill, 2002). Each
of these studies addressed the consequences of animals shifting from
one behavioral state (e.g., resting or foraging) to another behavioral
state (e.g., avoidance or escape behavior) because of human disturbance
or disturbance stimuli.
One consequence of behavioral avoidance results in the altered
energetic expenditure of marine mammals because energy is required to
move and avoid surface vessels or the sound field associated with
active sonar (Frid and Dill, 2002). Most animals can avoid that
energetic cost by swimming away at slow speeds or speeds that
[[Page 5818]]
minimize the cost of transport (Miksis-Olds, 2006), as has been
demonstrated in Florida manatees (Miksis-Olds, 2006).
Those energetic costs increase, however, when animals shift from a
resting state, which is designed to conserve an animal's energy, to an
active state that consumes energy the animal would have conserved had
it not been disturbed. Marine mammals that have been disturbed by
anthropogenic noise and vessel approaches are commonly reported to
shift from resting to active behavioral states, which would imply that
they incur an energy cost.
Morete et al., (2007) reported that undisturbed humpback whale cows
that were accompanied by their calves were frequently observed resting
while their calves circled them (milling). When vessels approached, the
amount of time cows and calves spent resting and milling, respectively,
declined significantly. These results are similar to those reported by
Scheidat et al. (2004) for the humpback whales they observed off the
coast of Ecuador.
Constantine and Brunton (2001) reported that bottlenose dolphins in
the Bay of Islands, New Zealand engaged in resting behavior just 5
percent of the time when vessels were within 300 m, compared with 83
percent of the time when vessels were not present. However, Heenehan et
al. (2016) report that results of a study of the response of Hawaiian
spinner dolphins to human disturbance suggest that the key factor is
not the sheer presence or magnitude of human activities, but rather the
directed interactions and dolphin-focused activities that elicit
responses from dolphins at rest. This information again illustrates the
importance of context in regard to whether an animal will respond to a
stimulus. Miksis-Olds (2006) and Miksis-Olds et al. (2005) reported
that Florida manatees in Sarasota Bay, Florida, reduced the amount of
time they spent milling and increased the amount of time they spent
feeding when background noise levels increased. Although the acute
costs of these changes in behavior are not likely to exceed an animal's
ability to compensate, the chronic costs of these behavioral shifts are
uncertain. Attention is the cognitive process of selectively
concentrating on one aspect of an animal's environment while ignoring
other things (Posner, 1994). Because animals (including humans) have
limited cognitive resources, there is a limit to how much sensory
information they can process at any time. The phenomenon called
``attentional capture'' occurs when a stimulus (usually a stimulus that
an animal is not concentrating on or attending to) ``captures'' an
animal's attention. This shift in attention can occur consciously or
subconsciously (for example, when an animal hears sounds that it
associates with the approach of a predator) and the shift in attention
can be sudden (Dukas, 2002; van Rij, 2007). Once a stimulus has
captured an animal's attention, the animal can respond by ignoring the
stimulus, assuming a ``watch and wait'' posture, or treat the stimulus
as a disturbance and respond accordingly, which includes scanning for
the source of the stimulus or ``vigilance'' (Cowlishaw et al., 2004).
Vigilance is normally an adaptive behavior that helps animals
determine the presence or absence of predators, assess their distance
from conspecifics, or to attend cues from prey (Bednekoff and Lima,
1998; Treves, 2000). Despite those benefits, however, vigilance has a
cost of time; when animals focus their attention on specific
environmental cues, they are not attending to other activities such as
foraging or resting. These effects have generally not been demonstrated
for marine mammals, but studies involving fish and terrestrial animals
have shown that increased vigilance may substantially reduce feeding
rates (Saino, 1994; Beauchamp and Livoreil, 1997; Fritz et al., 2002;
Purser and Radford, 2011). Animals will spend more time being vigilant,
which may translate to less time foraging or resting, when disturbance
stimuli approach them more directly, remain at closer distances, have a
greater group size (e.g., multiple surface vessels), or when they co-
occur with times that an animal perceives increased risk (e.g., when
they are giving birth or accompanied by a calf). Most of the published
literature, however, suggests that direct approaches will increase the
amount of time animals will dedicate to being vigilant. An example of
this concept with terrestrial species involved bighorn sheep and Dall's
sheep, which dedicated more time being vigilant, and less time resting
or foraging, when aircraft made direct approaches over them (Frid,
2001; Stockwell et al., 1991). Vigilance has also been documented in
pinnipeds at haul out sites where resting may be disturbed when seals
become alerted and/or flush into the water due to a variety of
disturbances, which may be anthropogenic (noise and/or visual stimuli)
or due to other natural causes such as other pinnipeds (Richardson et
al., 1995; Southall et al., 2007; VanBlaricom, 2010; and Lozano and
Hente, 2014).
Chronic disturbance can cause population declines through reduction
of fitness (e.g., decline in body condition) and subsequent reduction
in reproductive success, survival, or both (e.g., Harrington and
Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). For example,
Madsen (1994) reported that pink-footed geese (Anser brachyrhynchus) in
undisturbed habitat gained body mass and had about a 46 percent
reproductive success rate compared with geese in disturbed habitat
(being consistently scared off the fields on which they were foraging)
which did not gain mass and had a 17 percent reproductive success rate.
Similar reductions in reproductive success have been reported for mule
deer (Odocoileus hemionus) disturbed by all-terrain vehicles (Yarmoloy
et al., 1988), caribou (Rangifer tarandus caribou) disturbed by seismic
exploration blasts (Bradshaw et al., 1998), and caribou disturbed by
low-elevation military jet fights (Luick et al., 1996, Harrington and
Veitch, 1992). Similarly, a study of elk (Cervus elaphus) that were
disturbed experimentally by pedestrians concluded that the ratio of
young to mothers was inversely related to disturbance rate (Phillips
and Alldredge, 2000). However, Ridgway et al. (2006) reported that
increased vigilance in bottlenose dolphins exposed to sound over a
five-day period in open-air, open-water enclosures in San Diego Bay did
not cause any sleep deprivation or stress effects such as changes in
cortisol or epinephrine levels.
The primary mechanism by which increased vigilance and disturbance
appear to affect the fitness of individual animals is by disrupting an
animal's time budget and, as a result, reducing the time they might
spend foraging and resting (which increases an animal's activity rate
and energy demand while decreasing their caloric intake/energy). An
example of this concept with terrestrial species involved a study of
grizzly bears (Ursus horribilis) that reported that bears disturbed by
hikers reduced their energy intake by an average of 12 kilocalories/min
(50.2 x 103 kiloJoules/min), and spent energy fleeing or acting
aggressively toward hikers (White et al., 1999).
Lusseau and Bejder (2007) present data from three long-term studies
illustrating the connections between disturbance from whale-watching
boats and population-level effects in cetaceans. In Sharks Bay
Australia, the abundance of bottlenose dolphins was compared within
adjacent control and tourism sites over three consecutive 4.5-year
periods of increasing tourism levels. Between the second and third
[[Page 5819]]
time periods, in which tourism doubled, dolphin abundance decreased by
15 percent in the tourism area and did not change significantly in the
control area. In Fiordland, New Zealand, two populations (Milford and
Doubtful Sounds) of bottlenose dolphins with tourism levels that
differed by a factor of seven were observed and significant increases
in travelling time and decreases in resting time were documented for
both. Consistent short-term avoidance strategies were observed in
response to tour boats until a threshold of disturbance was reached
(average 68 minutes between interactions), after which the response
switched to a longer-term habitat displacement strategy. For one
population, tourism only occurred in a part of the home range. However,
tourism occurred throughout the home range of the Doubtful Sound
population and once boat traffic increased beyond the 68-minute
threshold (resulting in abandonment of their home range/preferred
habitat), reproductive success drastically decreased (increased
stillbirths) and abundance decreased significantly (from 67 to 56
individuals in a short period). Last, in a study of northern resident
killer whales off Vancouver Island, exposure to boat traffic was shown
to reduce foraging opportunities and increase traveling time. A simple
bioenergetics model was applied to show that the reduced foraging
opportunities equated to a decreased energy intake of 18 percent, while
the increased traveling incurred an increased energy output of 3-4
percent, which suggests that a management action based on avoiding
interference with foraging might be particularly effective.
On a related note, many animals perform vital functions, such as
feeding, resting, traveling, and socializing, on a diel cycle (24-hr
cycle). Behavioral reactions to noise exposure (such as disruption of
critical life functions, displacement, or avoidance of important
habitat) are more likely to be significant for fitness if they last
more than one diel cycle or recur on subsequent days (Southall et al.,
2007). Consequently, a behavioral response lasting less than one day
and not recurring on subsequent days is not considered particularly
severe unless it could directly affect reproduction or survival
(Southall et al., 2007). It is important to note the difference between
behavioral reactions lasting or recurring over multiple days and
anthropogenic activities lasting or recurring over multiple days. For
example, just because at-sea exercises last for multiple days does not
necessarily mean that individual animals will be either exposed to
those activity-related stressors (i.e., sonar) for multiple days or
further, exposed in a manner that would result in sustained multi-day
substantive behavioral responses. Stone (2015a) reported data from at-
sea observations during 1,196 airgun surveys from 1994 to 2010. When
large arrays of airguns (considered to be 500 in\3\ or more) were
firing, lateral displacement, more localized avoidance, or other
changes in behavior were evident for most odontocetes. However,
significant responses to large arrays were found only for the minke
whale and fin whale. Behavioral responses observed included changes in
swimming or surfacing behavior, with indications that cetaceans
remained near the water surface at these times. Cetaceans were recorded
as feeding less often when large arrays were active. Behavioral
observations of gray whales during an air gun survey monitored whale
movements and respirations pre-, during-, and post-seismic survey
(Gailey et al., 2016). Behavioral state and water depth were the best
`natural' predictors of whale movements and respiration and, after
considering natural variation, none of the response variables were
significantly associated with survey or vessel sounds.
In order to understand how the effects of activities may or may not
impact species and stocks of marine mammals, it is necessary to
understand not only what the likely disturbances are going to be, but
how those disturbances may affect the reproductive success and
survivorship of individuals, and then how those impacts to individuals
translate to population-level effects. Following on the earlier work of
a committee of the U.S. National Research Council (NRC, 2005), New et
al. (2014), in an effort termed the Potential Consequences of
Disturbance (PCoD), outline an updated conceptual model of the
relationships linking disturbance to changes in behavior and
physiology, health, vital rates, and population dynamics. In this
framework, behavioral and physiological changes can have direct (acute)
effects on vital rates, such as when changes in habitat use or
increased stress levels raise the probability of mother-calf separation
or predation; they can have indirect and long-term (chronic) effects on
vital rates, such as when changes in time/energy budgets or increased
disease susceptibility affect health, which then affects vital rates;
or they can have no effect to vital rates (New et al., 2014). In
addition to outlining this general framework and compiling the relevant
literature that supports it, the authors chose four example species for
which extensive long-term monitoring data exist (southern elephant
seals, North Atlantic right whales, Ziphidae beaked whales, and
bottlenose dolphins) and developed state-space energetic models that
can be used to effectively forecast longer-term, population-level
impacts from behavioral changes. While these are very specific models
with very specific data requirements that cannot yet be applied broadly
to project-specific risk assessments for the majority of species, they
are a critical first step towards being able to quantify the likelihood
of a population level effect.
Stranding and Mortality
The definition for a stranding under title IV of the MMPA is that
(A) a marine mammal is dead and is (i) on a beach or shore of the
United States; or (ii) in waters under the jurisdiction of the United
States (including any navigable waters); or (B) a marine mammal is
alive and is (i) on a beach or shore of the United States and is unable
to return to the water; (ii) on a beach or shore of the United States
and, although able to return to the water, is in need of apparent
medical attention; or (iii) in the waters under the jurisdiction of the
United States (including any navigable waters), but is unable to return
to its natural habitat under its own power or without assistance (see
MMPA section 410(3)). This definition is useful for considering
stranding events even when they occur beyond lands and waters under the
jurisdiction of the United States.
Marine mammal strandings have been linked to a variety of causes,
such as illness from exposure to infectious agents, biotoxins, or
parasites; starvation; unusual oceanographic or weather events; or
anthropogenic causes including fishery interaction, ship strike,
entrainment, entrapment, sound exposure, or combinations of these
stressors sustained concurrently or in series. Historically, the cause
or causes of most strandings have remained unknown (Geraci et al.,
1976; Eaton, 1979, Odell et al., 1980; Best, 1982), but the development
of trained, professional stranding response networks and improved
analyses have led to a greater understanding of marine mammal stranding
causes (Simeone and Moore 2017).
Numerous studies suggest that the physiology, behavior, habitat,
social relationships, age, or condition of cetaceans may cause them to
strand or might predispose them to strand when
[[Page 5820]]
exposed to another phenomenon. These suggestions are consistent with
the conclusions of numerous other studies that have demonstrated that
combinations of dissimilar stressors commonly combine to kill an animal
or dramatically reduce its fitness, even though one exposure without
the other does not produce the same result (Chroussos, 2000; Creel,
2005; DeVries et al., 2003; Fair and Becker, 2000; Foley et al., 2001;
Moberg, 2000; Relyea, 2005a; 2005b, Romero, 2004; Sih et al., 2004).
Historically, stranding reporting and response efforts have been
inconsistent, although significant improvements have occurred over the
last 25 years. Reporting forms for basic (``Level A'') information,
rehabilitation disposition, and human interaction have been
standardized nationally (available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/level-data-collection-marine-mammal-stranding-events). However, data collected beyond basic information
varies by region (and may vary from case to case), and are not
standardized across the United States. Logistical conditions such as
weather, time, location, and decomposition state may also affect the
ability of the stranding network to thoroughly examine a specimen
(Carretta et al., 2016b; Moore et al., 2013). While the investigation
of stranded animals provides insight into the types of threats marine
mammal populations face, full investigations are only possible and
conducted on a small fraction of the total number of strandings that
occur, limiting our understanding of the causes of strandings (Carretta
et al., 2016a). Additionally, and due to the variability in effort and
data collected, the ability to interpret long-term trends in stranded
marine mammals is complicated.
In the United States between 2001 and 2009, there were
approximately 9,895 cetacean strandings and 24,225 pinniped strandings
(34,120 total). From 2006-2017 there were 19,430 cetacean strandings
and 55,833 pinniped stranding (75,263 total) (P. Onens, NMFS, pers
comm. 2019). Several mass strandings (strandings that involve two or
more individuals of the same species, excluding a single mother-calf
pair) that have occurred over the past two decades have been associated
with anthropogenic activities that introduced sound into the marine
environment such as naval operations and seismic surveys. An in-depth
discussion of strandings is in the Navy's Technical Report on Marine
Mammal Strandings Associated with U.S. Navy Sonar Activities (U.S. Navy
Marine Mammal Program & Space and Naval Warfare Systems Command Center
Pacific, 2017).
Worldwide, there have been several efforts to identify
relationships between cetacean mass stranding events and military
active sonar (Cox et al., 2006, Hildebrand, 2004; IWC, 2005; Taylor et
al., 2004). For example, based on a review of mass stranding events
around the world consisting of two or more individuals of Cuvier's
beaked whales, records from the International Whaling Commission (IWC)
(2005) show that a quarter (9 of 41) were associated with concurrent
naval patrol, explosion, maneuvers, or MFAS. D'Amico et al. (2009)
reviewed beaked whale stranding data compiled primarily from the
published literature, which provides an incomplete record of stranding
events, as many are not written up for publication, along with
unpublished information from some regions of the world.
Most of the stranding events reviewed by the IWC involved beaked
whales. A mass stranding of Cuvier's beaked whales in the eastern
Mediterranean Sea occurred in 1996 (Frantzis, 1998), and mass stranding
events involving Gervais' beaked whales, Blainville's beaked whales,
and Cuvier's beaked whales occurred off the coast of the Canary Islands
in the late 1980s (Simmonds and Lopez-Jurado, 1991). The stranding
events that occurred in the Canary Islands and Kyparissiakos Gulf in
the late 1990s and the Bahamas in 2000 have been the most intensively-
studied mass stranding events and have been associated with naval
maneuvers involving the use of tactical sonar. Other cetacean species
with naval sonar implicated in stranding events include harbor porpoise
(Phocoena phocoena) (Norman et al., 2004, Wright et al., 2013) and
common dolphin (Delphinus delphis) (Jepson and Deaville 2009).
Strandings Associated With Impulsive Sound
Silver Strand
During a Navy training event on March 4, 2011 at the Silver Strand
Training Complex in San Diego, California, three or possibly four
dolphins were killed in an explosion. During an underwater detonation
training event, a pod of 100 to 150 long-beaked common dolphins were
observed moving towards the 700-yd (640.1 m) exclusion zone around the
explosive charge, monitored by personnel in a safety boat and
participants in a dive boat. Approximately five minutes remained on a
time-delay fuse connected to a single 8.76 lb (3.97 kg) explosive
charge (C-4 and detonation cord). Although the dive boat was placed
between the pod and the explosive in an effort to guide the dolphins
away from the area, that effort was unsuccessful and three long-beaked
common dolphins near the explosion died. In addition to the three
dolphins found dead on March 4, the remains of a fourth dolphin were
discovered on March 7, 2011 near Oceanside, California (3 days later
and approximately 68 km north of the detonation), which might also have
been related to this event. Association of the fourth stranding with
the training event is uncertain because dolphins strand on a regular
basis in the San Diego area. Details such as the dolphins' depth and
distance from the explosive at the time of the detonation could not be
estimated from the 250 yd (228.6 m) standoff point of the observers in
the dive boat or the safety boat.
These dolphin mortalities are the only known occurrence of a U.S.
Navy training or testing event involving impulsive energy (underwater
detonation) that caused mortality or injury to a marine mammal. Despite
this being a rare occurrence, the Navy has reviewed training
requirements, safety procedures, and possible mitigation measures and
implemented changes to reduce the potential for this to occur in the
future. Discussions of procedures associated with underwater explosives
training and other training events are presented in the Proposed
Mitigation Measures section.
Kyle of Durness, Scotland
On July 22, 2011 a mass stranding event involving long-finned pilot
whales occurred at Kyle of Durness, Scotland. An investigation by
Brownlow et al. (2015) considered unexploded ordnance detonation
activities at a Ministry of Defense bombing range, conducted by the
Royal Navy prior to and during the strandings, as a plausible
contributing factor in the mass stranding event. While Brownlow et al.
(2015) concluded that the serial detonations of underwater ordnance
were an influential factor in the mass stranding event (along with the
presence of a potentially compromised animal and navigational error in
a topographically complex region) they also suggest that mitigation
measures--which included observations from a zodiac only and by
personnel not experienced in marine mammal observation, among other
deficiencies--were likely insufficient to assess if cetaceans were in
the vicinity of the detonations. The authors also cite information from
the Ministry of Defense indicating ``an extraordinarily
[[Page 5821]]
high level of activity'' (i.e., frequency and intensity of underwater
explosions) on the range in the days leading up to the stranding.
Gulf of California, Mexico
One stranding event was contemporaneous with and reasonably
associated spatially with the use of seismic air guns. This event
occurred in the Gulf of California, coincident with seismic reflection
profiling by the R/V Maurice Ewing operated by Columbia University's
Lamont-Doherty Earth Observatory and involved two Cuvier's beaked
whales (Hildebrand, 2004). The vessel had been firing an array of 20
air guns with a total volume of 8,500 in\3\ (Hildebrand, 2004; Taylor
et al., 2004).
Strandings Associated With Active Sonar
Over the past 21 years, there have been five stranding events
coincident with U.S. Navy MF active sonar use in which exposure to
sonar is believed to have been a contributing factor: Greece (1996);
the Bahamas (2000); Madeira (2000); Canary Islands (2002); and Spain
(2006) (Cox et al., 2006; Fernandez, 2006; U.S. Navy Marine Mammal
Program & Space and Naval Warfare Systems Command Center Pacific,
2017). These five mass strandings have resulted in about 40 known
cetacean deaths consisting mostly of beaked whales and with close
linkages to mid-frequency active sonar activity. In these
circumstances, exposure to non-impulsive acoustic energy was considered
a potential indirect cause of death of the marine mammals (Cox et al.,
2006). Only one of these stranding events, the Bahamas (2000), was
associated with exercises conducted by the U.S. Navy. Additionally, in
2004, during the Rim of the Pacific (RIMPAC) exercises, between 150 and
200 usually pelagic melon-headed whales occupied the shallow waters of
Hanalei Bay, Kauai, Hawaii for over 28 hours. NMFS determined that MFAS
was a plausible, if not likely, contributing factor in what may have
been a confluence of events that led to the Hanalei Bay stranding. A
number of other stranding events coincident with the operation of MFAS,
including the death of beaked whales or other species (minke whales,
dwarf sperm whales, pilot whales), have been reported; however, the
majority have not been investigated to the degree necessary to
determine the cause of the stranding. Most recently, the Independent
Scientific Review Panel investigating potential contributing factors to
a 2008 mass stranding of melon-headed whales in Antsohihy, Madagascar
released its final report suggesting that the stranding was likely
initially triggered by an industry seismic survey. This report suggests
that the operation of a commercial high-powered 12 kHz multi-beam
echosounder during an industry seismic survey was a plausible and
likely initial trigger that caused a large group of melon-headed whales
to leave their typical habitat and then ultimately strand as a result
of secondary factors such as malnourishment and dehydration. The report
indicates that the risk of this particular convergence of factors and
ultimate outcome is likely very low, but recommends that the potential
be considered in environmental planning. Because of the association
between tactical mid-frequency active sonar use and a small number of
marine mammal strandings, the Navy and NMFS have been considering and
addressing the potential for strandings in association with Navy
activities for years. In addition to the proposed mitigation measures
intended to more broadly minimize impacts to marine mammals, the Navy
will abide by the Notification and Reporting Plan, which sets out
notification, reporting, and other requirements when dead, injured, or
stranded marine mammals are detected in certain circumstances.
Greece (1996)
Twelve Cuvier's beaked whales stranded atypically (in both time and
space) along a 38.2-km strand of the Kyparissiakos Gulf coast on May 12
and 13, 1996 (Frantzis, 1998). From May 11 through May 15, the North
Atlantic Treaty Organization (NATO) research vessel Alliance was
conducting sonar tests with signals of 600 Hz and 3 kHz and source
levels of 228 and 226 dB re: 1[mu]Pa, respectively (D'Amico and
Verboom, 1998; D'Spain et al., 2006). The timing and location of the
testing encompassed the time and location of the strandings (Frantzis,
1998).
Necropsies of eight of the animals were performed but were limited
to basic external examination and sampling of stomach contents, blood,
and skin. No ears or organs were collected, and no histological samples
were preserved. No apparent abnormalities or wounds were found.
Examination of photos of the animals, taken soon after their death,
revealed that the eyes of at least four of the individuals were
bleeding. Photos were taken soon after their death (Frantzis, 2004).
Stomach contents contained the flesh of cephalopods, indicating that
feeding had recently taken place (Frantzis, 1998).
All available information regarding the conditions associated with
this stranding event were compiled, and many potential causes were
examined including major pollution events, prominent tectonic activity,
unusual physical or meteorological events, magnetic anomalies,
epizootics, and conventional military activities (International Council
for the Exploration of the Sea, 2005a). However, none of these
potential causes coincided in time or space with the mass stranding, or
could explain its characteristics (International Council for the
Exploration of the Sea, 2005a). The robust condition of the animals,
plus the recent stomach contents, is inconsistent with pathogenic
causes. In addition, environmental causes can be ruled out as there
were no unusual environmental circumstances or events before or during
this time period and within the general proximity (Frantzis, 2004).
Because of the rarity of this mass stranding of Cuvier's beaked
whales in the Kyparissiakos Gulf (first one in historical records), the
probability for the two events (the military exercises and the
strandings) to coincide in time and location, while being independent
of each other, was thought to be extremely low (Frantzis, 1998).
However, because full necropsies had not been conducted, and no
abnormalities were noted, the cause of the strandings could not be
precisely determined (Cox et al., 2006). A Bioacoustics Panel convened
by NATO concluded that the evidence available did not allow them to
accept or reject sonar exposures as a causal agent in these stranding
events. The analysis of this stranding event provided support for, but
no clear evidence for, the cause-and-effect relationship of tactical
sonar training activities and beaked whale strandings (Cox et al.,
2006).
Bahamas (2000)
NMFS and the Navy prepared a joint report addressing the multi-
species stranding in the Bahamas in 2000, which took place within 24
hrs of U.S. Navy ships using MFAS as they passed through the Northeast
and Northwest Providence Channels on March 15-16, 2000. The ships,
which operated both AN/SQS-53C and AN/SQS-56, moved through the channel
while emitting sonar pings approximately every 24 seconds. Of the 17
cetaceans that stranded over a 36-hour period (Cuvier's beaked whales,
Blainville's beaked whales, minke whales, and a spotted dolphin), seven
animals died on the beach (five Cuvier's beaked whales, one
Blainville's beaked whale, and the spotted dolphin), while the other 10
were returned to the water alive (though their ultimate fate is
unknown). As
[[Page 5822]]
discussed in the Bahamas report (DOC/DON, 2001), there is no likely
association between the minke whale and spotted dolphin strandings and
the operation of MFAS.
Necropsies were performed on five of the stranded beaked whales.
All five necropsied beaked whales were in good body condition, showing
no signs of infection, disease, ship strike, blunt trauma, or fishery
related injuries, and three still had food remains in their stomachs.
Auditory structural damage was discovered in four of the whales,
specifically bloody effusions or hemorrhaging around the ears.
Bilateral intracochlear and unilateral temporal region subarachnoid
hemorrhage, with blood clots in the lateral ventricles, were found in
two of the whales. Three of the whales had small hemorrhages in their
acoustic fats (located along the jaw and in the melon).
A comprehensive investigation was conducted and all possible causes
of the stranding event were considered, whether they seemed likely at
the outset or not. Based on the way in which the strandings coincided
with ongoing naval activity involving tactical MFAS use, in terms of
both time and geography, the nature of the physiological effects
experienced by the dead animals, and the absence of any other acoustic
sources, the investigation team concluded that MFAS aboard U.S. Navy
ships that were in use during the active sonar exercise in question
were the most plausible source of this acoustic or impulse trauma to
beaked whales. This sound source was active in a complex environment
that included the presence of a surface duct, unusual and steep
bathymetry, a constricted channel with limited egress, intensive use of
multiple, active sonar units over an extended period of time, and the
presence of beaked whales that appear to be sensitive to the
frequencies produced by these active sonars. The investigation team
concluded that the cause of this stranding event was the confluence of
the Navy MFAS and these contributory factors working together, and
further recommended that the Navy avoid operating MFAS in situations
where these five factors would be likely to occur. This report does not
conclude that all five of these factors must be present for a stranding
to occur, nor that beaked whales are the only species that could
potentially be affected by the confluence of the other factors. Based
on this, NMFS believes that the operation of MFAS in situations where
surface ducts exist, or in marine environments defined by steep
bathymetry and/or constricted channels may increase the likelihood of
producing a sound field with the potential to cause cetaceans
(especially beaked whales) to strand, and therefore, suggests the need
for increased vigilance while operating MFAS in these areas, especially
when beaked whales (or potentially other deep divers) are likely
present.
Madeira, Portugal (2000)
From May 10-14, 2000, three Cuvier's beaked whales were found
atypically stranded on two islands in the Madeira archipelago, Portugal
(Cox et al., 2006). A fourth animal was reported floating in the
Madeiran waters by fisherman but did not come ashore (Woods Hole
Oceanographic Institution, 2005). Joint NATO amphibious training
peacekeeping exercises involving participants from 17 countries and 80
warships, took place in Portugal during May 2-15, 2000.
The bodies of the three stranded whales were examined post mortem
(Woods Hole Oceanographic Institution, 2005), though only one of the
stranded whales was fresh enough (24 hours after stranding) to be
necropsied (Cox et al., 2006). Results from the necropsy revealed
evidence of hemorrhage and congestion in the right lung and both
kidneys (Cox et al., 2006). There was also evidence of intercochlear
and intracranial hemorrhage similar to that which was observed in the
whales that stranded in the Bahamas event (Cox et al., 2006). There
were no signs of blunt trauma, and no major fractures (Woods Hole
Oceanographic Institution, 2005). The cranial sinuses and airways were
found to be clear with little or no fluid deposition, which may
indicate good preservation of tissues (Woods Hole Oceanographic
Institution, 2005). Several observations on the Madeira stranded beaked
whales, such as the pattern of injury to the auditory system, are the
same as those observed in the Bahamas strandings. Blood in and around
the eyes, kidney lesions, pleural hemorrhages, and congestion in the
lungs are particularly consistent with the pathologies from the whales
stranded in the Bahamas, and are consistent with stress and pressure
related trauma. The similarities in pathology and stranding patterns
between these two events suggest that a similar pressure event may have
precipitated or contributed to the strandings at both sites (Woods Hole
Oceanographic Institution, 2005).
Even though no definitive causal link can be made between the
stranding event and naval exercises, certain conditions may have
existed in the exercise area that, in their aggregate, may have
contributed to the marine mammal strandings (Freitas, 2004): Exercises
were conducted in areas of at least 547 fathoms (1,000 m) depth near a
shoreline where there is a rapid change in bathymetry on the order of
547 to 3,281 fathoms (1,000 to 6,000 m) occurring across a relatively
short horizontal distance (Freitas, 2004); multiple ships were
operating around Madeira, though it is not known if MFAS was used, and
the specifics of the sound sources used are unknown (Cox et al., 2006,
Freitas, 2004); and exercises took place in an area surrounded by
landmasses separated by less than 35 nmi (65 km) and at least 10 NM (19
km) in length, or in an embayment. Exercises involving multiple ships
employing MFAS near land may produce sound directed towards a channel
or embayment that may cut off the lines of egress for marine mammals
(Freitas, 2004).
Canary Islands, Spain (2002)
The southeastern area within the Canary Islands is well known for
aggregations of beaked whales due to its ocean depths of greater than
547 fathoms (1,000 m) within a few hundred meters of the coastline
(Fernandez et al., 2005). On September 24, 2002, 14 beaked whales were
found stranded on Fuerteventura and Lanzarote Islands in the Canary
Islands (International Council for Exploration of the Sea, 2005a).
Seven whales died, while the remaining seven live whales were returned
to deeper waters (Fernandez et al., 2005). Four beaked whales were
found stranded dead over the next three days either on the coast or
floating offshore. These strandings occurred within near proximity of
an international naval exercise that utilized MFAS and involved
numerous surface warships and several submarines. Strandings began
about four hours after the onset of MFAS activity (International
Council for Exploration of the Sea, 2005a; Fernandez et al., 2005).
Eight Cuvier's beaked whales, one Blainville's beaked whale, and
one Gervais' beaked whale were necropsied, 6 of them within 12 hours of
stranding (Fernandez et al., 2005). No pathogenic bacteria were
isolated from the carcasses (Jepson et al., 2003). The animals
displayed severe vascular congestion and hemorrhage especially around
the tissues in the jaw, ears, brain, and kidneys, displaying marked
disseminated microvascular hemorrhages associated with widespread fat
emboli (Jepson et al., 2003; International Council for Exploration of
the Sea, 2005a). Several organs contained intravascular bubbles,
although definitive evidence of gas embolism in vivo is difficult to
[[Page 5823]]
determine after death (Jepson et al., 2003). The livers of the
necropsied animals were the most consistently affected organ, which
contained macroscopic gas-filled cavities and had variable degrees of
fibrotic encapsulation. In some animals, cavitary lesions had
extensively replaced the normal tissue (Jepson et al., 2003). Stomachs
contained a large amount of fresh and undigested contents, suggesting a
rapid onset of disease and death (Fernandez et al., 2005). Head and
neck lymph nodes were enlarged and congested, and parasites were found
in the kidneys of all animals (Fernandez et al., 2005).
The association of NATO MFAS use close in space and time to the
beaked whale strandings, and the similarity between this stranding
event and previous beaked whale mass strandings coincident with sonar
use, suggests that a similar scenario and causative mechanism of
stranding may be shared between the events. Beaked whales stranded in
this event demonstrated brain and auditory system injuries,
hemorrhages, and congestion in multiple organs, similar to the
pathological findings of the Bahamas and Madeira stranding events. In
addition, the necropsy results of Canary Islands stranding event lead
to the hypothesis that the presence of disseminated and widespread gas
bubbles and fat emboli were indicative of nitrogen bubble formation,
similar to what might be expected in decompression sickness (Jepson et
al., 2003; Fern[aacute]ndez et al., 2005).
Hanalei Bay (2004)
On July 3 and 4, 2004, approximately 150 to 200 melon-headed whales
occupied the shallow waters of Hanalei Bay, Kauai, Hawaii for over 28
hrs. Attendees of a canoe blessing observed the animals entering the
Bay in a single wave formation at 7 a.m. on July 3, 2004. The animals
were observed moving back into the shore from the mouth of the Bay at 9
a.m. The usually pelagic animals milled in the shallow bay and were
returned to deeper water with human assistance beginning at 9:30 a.m.
on July 4, 2004, and were out of sight by 10:30 a.m.
Only one animal, a calf, was known to have died following this
event. The animal was noted alive and alone in the Bay on the afternoon
of July 4, 2004, and was found dead in the Bay the morning of July 5,
2004. A full necropsy, magnetic resonance imaging, and computerized
tomography examination were performed on the calf to determine the
manner and cause of death. The combination of imaging, necropsy and
histological analyses found no evidence of infectious, internal
traumatic, congenital, or toxic factors. Cause of death could not be
definitively determined, but it is likely that maternal separation,
poor nutritional condition, and dehydration contributed to the final
demise of the animal. Although it is not known when the calf was
separated from its mother, the animals' movement into the Bay and
subsequent milling and re-grouping may have contributed to the
separation or lack of nursing, especially if the maternal bond was weak
or this was an inexperienced mother with her first calf.
Environmental factors, abiotic and biotic, were analyzed for any
anomalous occurrences that would have contributed to the animals
entering and remaining in Hanalei Bay. The Bay's bathymetry is similar
to many other sites within the Hawaiian Island chain and dissimilar to
sites that have been associated with mass strandings in other parts of
the U.S. The weather conditions appeared to be normal for that time of
year with no fronts or other significant features noted. There was no
evidence of unusual distribution, occurrence of predator or prey
species, or unusual harmful algal blooms, although Mobley et al. (2007)
suggested that the full moon cycle that occurred at that time may have
influenced a run of squid into the Bay. Weather patterns and bathymetry
that have been associated with mass strandings elsewhere were not found
to occur in this instance.
The Hanalei event was spatially and temporally correlated with
RIMPAC. Official sonar training and tracking exercises in the Pacific
Missile Range Facility (PMRF) warning area did not commence until
approximately 8 a.m. on July 3 and were thus ruled out as a possible
trigger for the initial movement into the Bay. However, six naval
surface vessels transiting to the operational area on July 2
intermittently transmitted active sonar (for approximately nine hours
total from 1:15 p.m. to 12:30 a.m.) as they approached from the south.
The potential for these transmissions to have triggered the whales'
movement into Hanalei Bay was investigated. Analyses with the
information available indicated that animals to the south and east of
Kaua'i could have detected active sonar transmissions on July 2, and
reached Hanalei Bay on or before 7 a.m. on July 3. However, data
limitations regarding the position of the whales prior to their arrival
in the Bay, the magnitude of sonar exposure, behavioral responses of
melon-headed whales to acoustic stimuli, and other possible relevant
factors preclude a conclusive finding regarding the role of sonar in
triggering this event. Propagation modeling suggests that transmissions
from sonar use during the July 3 exercise in the PMRF warning area may
have been detectable at the mouth of the Bay. If the animals responded
negatively to these signals, it may have contributed to their continued
presence in the Bay. The U.S. Navy ceased all active sonar
transmissions during exercises in this range on the afternoon of July
3. Subsequent to the cessation of sonar use, the animals were herded
out of the Bay.
While causation of this stranding event may never be unequivocally
determined, NMFS consider the active sonar transmissions of July 2-3,
2004, a plausible, if not likely, contributing factor in what may have
been a confluence of events. This conclusion is based on the following:
(1) The evidently anomalous nature of the stranding; (2) its close
spatiotemporal correlation with wide-scale, sustained use of sonar
systems previously associated with stranding of deep-diving marine
mammals; (3) the directed movement of two groups of transmitting
vessels toward the southeast and southwest coast of Kauai; (4) the
results of acoustic propagation modeling and an analysis of possible
animal transit times to the Bay; and (5) the absence of any other
compelling causative explanation. The initiation and persistence of
this event may have resulted from an interaction of biological and
physical factors. The biological factors may have included the presence
of an apparently uncommon, deep-diving cetacean species (and possibly
an offshore, non-resident group), social interactions among the animals
before or after they entered the Bay, and/or unknown predator or prey
conditions. The physical factors may have included the presence of
nearby deep water, multiple vessels transiting in a directed manner
while transmitting active sonar over a sustained period, the presence
of surface sound ducting conditions, and/or intermittent and random
human interactions while the animals were in the Bay.
A separate event involving melon-headed whales and rough-toothed
dolphins took place over the same period of time in the Northern
Mariana Islands (Jefferson et al., 2006), which is several thousand
miles from Hawaii. Some 500 to 700 melon-headed whales came into
Sasanhaya Bay on July 4, 2004, near the island of Rota and then left of
their own accord after 5.5 hours; no known active sonar transmissions
occurred in the vicinity of that event. The Rota incident led to
scientific debate regarding what, if any,
[[Page 5824]]
relationship the event had to the simultaneous events in Hawaii and
whether they might be related by some common factor (e.g., there was a
full moon on July 2, 2004, as well as during other melon-headed whale
strandings and nearshore aggregations (Brownell et al., 2009; Lignon et
al., 2007; Mobley et al., 2007). Brownell et al. (2009) compared the
two incidents, along with one other stranding incident at Nuka Hiva in
French Polynesia and normal resting behaviors observed at Palmyra
Island, in regard to physical features in the areas, melon-headed whale
behavior, and lunar cycles. Brownell et al., (2009) concluded that the
rapid entry of the whales into Hanalei Bay, their movement into very
shallow water far from the 100-m contour, their milling behavior
(typical pre-stranding behavior), and their reluctance to leave the bay
constituted an unusual event that was not similar to the events that
occurred at Rota (but was similar to the events at Palmyra), which
appear to be similar to observations of melon-headed whales resting
normally at Palmyra Island. Additionally, there was no correlation
between lunar cycle and the types of behaviors observed in the Brownell
et al. (2009) examples.
Spain (2006)
The Spanish Cetacean Society reported an atypical mass stranding of
four beaked whales that occurred January 26, 2006, on the southeast
coast of Spain, near Moj[aacute]car (Gulf of Vera) in the Western
Mediterranean Sea. According to the report, two of the whales were
discovered the evening of January 26 and were found to be still alive.
Two other whales were discovered during the day on January 27, but had
already died. The first three animals were located near the town of
Moj[aacute]car and the fourth animal was found dead, a few kilometers
north of the first three animals. From January 25-26, 2006, Standing
NATO Response Force Maritime Group Two (five of seven ships including
one U.S. ship under NATO Operational Control) had conducted active
sonar training against a Spanish submarine within 50 NM (93 km) of the
stranding site.
Veterinary pathologists necropsied the two male and two female
Cuvier's beaked whales. According to the pathologists, the most likely
primary cause of this type of beaked whale mass stranding event was
anthropogenic acoustic activities, most probably anti-submarine MFAS
used during the military naval exercises. However, no positive acoustic
link was established as a direct cause of the stranding. Even though no
causal link can be made between the stranding event and naval
exercises, certain conditions may have existed in the exercise area
that, in their aggregate, may have contributed to the marine mammal
strandings (Freitas, 2004). Exercises were conducted in areas of at
least 547 fathoms (1,000 m) depth near a shoreline where there is a
rapid change in bathymetry on the order of 547 to 3,281 fathoms (1,000
to 6,000 m) occurring across a relatively short horizontal distance
(Freitas, 2004). Multiple ships (in this instance, five) were operating
MFAS in the same area over extended periods of time (in this case, 20
hours) in close proximity; and exercises took place in an area
surrounded by landmasses, or in an embayment. Exercises involving
multiple ships employing MFAS near land may have produced sound
directed towards a channel or embayment that may have cut off the lines
of egress for the affected marine mammals (Freitas, 2004).
Behaviorally Mediated Responses to MFAS That May Lead to Stranding
Although the confluence of Navy MFAS with the other contributory
factors noted in the 2001 NMFS/Navy joint report was identified as the
cause of the 2000 Bahamas stranding event, the specific mechanisms that
led to that stranding (or the others) are not understood, and there is
uncertainty regarding the ordering of effects that led to the
stranding. It is unclear whether beaked whales were directly injured by
sound (e.g., acoustically mediated bubble growth, as addressed above)
prior to stranding or whether a behavioral response to sound occurred
that ultimately caused the beaked whales to be injured and strand.
Although causal relationships between beaked whale stranding events
and active sonar remain unknown, several authors have hypothesized that
stranding events involving these species in the Bahamas and Canary
Islands may have been triggered when the whales changed their dive
behavior in a startled response to exposure to active sonar or to
further avoid exposure (Cox et al., 2006; Rommel et al., 2006). These
authors proposed three mechanisms by which the behavioral responses of
beaked whales upon being exposed to active sonar might result in a
stranding event. These include the following: Gas bubble formation
caused by excessively fast surfacing; remaining at the surface too long
when tissues are supersaturated with nitrogen; or diving prematurely
when extended time at the surface is necessary to eliminate excess
nitrogen. More specifically, beaked whales that occur in deep waters
that are in close proximity to shallow waters (for example, the
``canyon areas'' that are cited in the Bahamas stranding event; see
D'Spain and D'Amico, 2006), may respond to active sonar by swimming
into shallow waters to avoid further exposures and strand if they were
not able to swim back to deeper waters. Second, beaked whales exposed
to active sonar might alter their dive behavior. Changes in their dive
behavior might cause them to remain at the surface or at depth for
extended periods of time which could lead to hypoxia directly by
increasing their oxygen demands or indirectly by increasing their
energy expenditures (to remain at depth) and increase their oxygen
demands as a result. If beaked whales are at depth when they detect a
ping from an active sonar transmission and change their dive profile,
this could lead to the formation of significant gas bubbles, which
could damage multiple organs or interfere with normal physiological
function (Cox et al., 2006; Rommel et al., 2006; Zimmer and Tyack,
2007). Baird et al. (2005) found that slow ascent rates from deep dives
and long periods of time spent within 50 m of the surface were typical
for both Cuvier's and Blainville's beaked whales, the two species
involved in mass strandings related to naval sonar. These two
behavioral mechanisms may be necessary to purge excessive dissolved
nitrogen concentrated in their tissues during their frequent long dives
(Baird et al., 2005). Baird et al. (2005) further suggests that
abnormally rapid ascents or premature dives in response to high-
intensity sonar could indirectly result in physical harm to the beaked
whales, through the mechanisms described above (gas bubble formation or
non-elimination of excess nitrogen). Because many species of marine
mammals make repetitive and prolonged dives to great depths, it has
long been assumed that marine mammals have evolved physiological
mechanisms to protect against the effects of rapid and repeated
decompressions. Although several investigators have identified
physiological adaptations that may protect marine mammals against
nitrogen gas supersaturation (alveolar collapse and elective
circulation; Kooyman et al., 1972; Ridgway and Howard, 1979), Ridgway
and Howard (1979) reported that bottlenose dolphins that were trained
to dive repeatedly had muscle tissues that were substantially
supersaturated with nitrogen gas. Houser et al. (2001) used these data
to model the accumulation of nitrogen gas within the muscle tissue of
other marine mammal species and concluded that
[[Page 5825]]
cetaceans that dive deep and have slow ascent or descent speeds would
have tissues that are more supersaturated with nitrogen gas than other
marine mammals. Based on these data, Cox et al. (2006) hypothesized
that a critical dive sequence might make beaked whales more prone to
stranding in response to acoustic exposures. The sequence began with
(1) very deep (to depths as deep as 2 km) and long (as long as 90
minutes) foraging dives; (2) relatively slow, controlled ascents; and
(3) a series of ``bounce'' dives between 100 and 400 m in depth (also
see Zimmer and Tyack, 2007). They concluded that acoustic exposures
that disrupted any part of this dive sequence (for example, causing
beaked whales to spend more time at surface without the bounce dives
that are necessary to recover from the deep dive) could produce
excessive levels of nitrogen supersaturation in their tissues, leading
to gas bubble and emboli formation that produces pathologies similar to
decompression sickness.
Zimmer and Tyack (2007) modeled nitrogen tension and bubble growth
in several tissue compartments for several hypothetical dive profiles
and concluded that repetitive shallow dives (defined as a dive where
depth does not exceed the depth of alveolar collapse, approximately 72
m for Cuvier's beaked whale), perhaps as a consequence of an extended
avoidance reaction to sonar sound, could pose a risk for decompression
sickness and that this risk should increase with the duration of the
response. Their models also suggested that unrealistically rapid rates
of ascent from normal dive behaviors are unlikely to result in
supersaturation to the extent that bubble formation would be expected.
Tyack et al. (2006) suggested that emboli observed in animals exposed
to mid-frequency range sonar (Jepson et al., 2003; Fernandez et al.,
2005; Fern[aacute]ndez et al., 2012) could stem from a behavioral
response that involves repeated dives shallower than the depth of lung
collapse. Given that nitrogen gas accumulation is a passive process
(i.e., nitrogen is metabolically inert), a bottlenose dolphin was
trained to repetitively dive a profile predicted to elevate nitrogen
saturation to the point that nitrogen bubble formation was predicted to
occur. However, inspection of the vascular system of the dolphin via
ultrasound did not demonstrate the formation of asymptomatic nitrogen
gas bubbles (Houser et al., 2007). Baird et al. (2008), in a beaked
whale tagging study off Hawaii, showed that deep dives are equally
common during day or night, but ``bounce dives'' are typically a
daytime behavior, possibly associated with visual predator avoidance.
This may indicate that ``bounce dives'' are associated with something
other than behavioral regulation of dissolved nitrogen levels, which
would be necessary day and night.
If marine mammals respond to a Navy vessel that is transmitting
active sonar in the same way that they might respond to a predator,
their probability of flight responses could increase when they perceive
that Navy vessels are approaching them directly, because a direct
approach may convey detection and intent to capture (Burger and
Gochfeld, 1981, 1990; Cooper, 1997, 1998). The probability of flight
responses could also increase as received levels of active sonar
increase (and the ship is, therefore, closer) and as ship speeds
increase (that is, as approach speeds increase). For example, the
probability of flight responses in Dall's sheep (Ovis dalli dalli)
(Frid 2001a, b), ringed seals (Phoca hispida) (Born et al., 1999),
Pacific brant (Branta bernic nigricans) and Canada geese (B.
canadensis) increased as a helicopter or fixed-wing aircraft approached
groups of these animals more directly (Ward et al., 1999). Bald eagles
(Haliaeetus leucocephalus) perched on trees alongside a river were also
more likely to flee from a paddle raft when their perches were closer
to the river or were closer to the ground (Steidl and Anthony, 1996).
Despite the many theories involving bubble formation (both as a
direct cause of injury, see Acoustically-Induced Bubble Formation Due
to Sonars and Other Pressure-related Injury section and an indirect
cause of stranding). Southall et al. (2007) summarizes that there is
either scientific disagreement or a lack of information regarding each
of the following important points: (1) Received acoustical exposure
conditions for animals involved in stranding events; (2) pathological
interpretation of observed lesions in stranded marine mammals; (3)
acoustic exposure conditions required to induce such physical trauma
directly; (4) whether noise exposure may cause behavioral reactions
(such as atypical diving behavior) that secondarily cause bubble
formation and tissue damage; and (5) the extent the post mortem
artifacts introduced by decomposition before sampling, handling,
freezing, or necropsy procedures affect interpretation of observed
lesions.
Strandings in the MITT Study Area
Although records of marine mammal strandings exist as far back as
1878 in Guam, reporting of marine mammal strandings across the Mariana
Islands has likely only become consistent in recent years. A variety of
marine mammals have historically stranded in the MITT Study Area and
have been documented by sources such as the Department of Lands and
Natural Resources Division of Fish and Wildlife and by the Department
of Agriculture, Division of Aquatic and Wildlife Resources. Species
that have stranded include pygmy and dwarf sperm whales, false killer
whales, melon-headed whales, striped dolphins, sperm whales, and beaked
whales.
The stranding of a pygmy sperm whale in 1997 (Trianni and Tenorio,
2012) is the only other confirmed occurrence of this species in the
MITT Study Area. There have been four known dwarf sperm whale
strandings in the Mariana Islands (Trianni and Tenorio, 2012; Uyeyama,
2014). Three false killer whale strandings occurred in 2000, 2003, and
2007 (Trianni and Tenorio, 2012; Uyeyama, 2014). There was a live
stranding of a melon-headed whale on the beach at Inarajan Bay, Guam in
1980 (Donaldson, 1983; Kami, 1982), and four individuals at Orote in
2009 (Uyeyama, 2014). Two striped dolphins stranding have occurred, one
recorded in July1985 (Eldredge, 1991, 2003) and a second in 1993 off
Saipan (Trianni and Tenorio, 2012). Six sperm whale stranding have
occurred between 1962 to 2018. Through January 2019, nine beaked whales
stranding events were reported in the Mariana Islands (Guam and
Saipan), with the first recorded stranding in 2007. All identified
beaked whales were Cuvier's beaked whales. Stranding events consisted
of 1-3 animals. A tenth event, and most recent stranding (live) event
of a Cuvier's beaked whale, occurred in November 2019 on Rota
(Commonwealth of the Northern Mariana Islands). A review of Navy
records indicates that sonar use occurred within 72 hours or 80 NM of
three of these stranding events (2011, 2015, and 2016) (C. Johnson,
Navy, pers. comm. 2019).
Potential Effects of Vessel Strike
Vessel collisions with marine mammals, also referred to as vessel
strikes or ship strikes, can result in death or serious injury of the
animal. Wounds resulting from ship strike may include massive trauma,
hemorrhaging, broken bones, or propeller lacerations (Knowlton and
Kraus, 2001). An animal at the surface could be struck directly by a
vessel, a surfacing animal could hit the bottom of a vessel, or an
animal just below the surface could be cut by a vessel's propeller.
Superficial strikes
[[Page 5826]]
may not kill or result in the death of the animal. Lethal interactions
are typically associated with large whales, which are occasionally
found draped across the bulbous bow of large commercial ships upon
arrival in port. Although smaller cetaceans are more maneuverable in
relation to large vessels than are large whales, they may also be
susceptible to strike. The severity of injuries typically depends on
the size and speed of the vessel (Knowlton and Kraus, 2001; Laist et
al., 2001; Vanderlaan and Taggart, 2007; Conn and Silber, 2013). Impact
forces increase with speed, as does the probability of a strike at a
given distance (Silber et al., 2010; Gende et al., 2011).
The most vulnerable marine mammals are those that spend extended
periods of time at the surface in order to restore oxygen levels within
their tissues after deep dives (e.g., the sperm whale). In addition,
some baleen whales seem generally unresponsive to vessel sound, making
them more susceptible to vessel collisions (Nowacek et al., 2004).
These species are primarily large, slow moving whales. Marine mammal
responses to vessels may include avoidance and changes in dive pattern
(NRC, 2003).
An examination of all known ship strikes from all shipping sources
(civilian and military) indicates vessel speed is a principal factor in
whether a vessel strike occurs and, if so, whether it results in
injury, serious injury, or mortality (Knowlton and Kraus, 2001; Laist
et al., 2001; Jensen and Silber, 2003; Pace and Silber, 2005;
Vanderlaan and Taggart, 2007; Conn and Silber 2013). In assessing
records in which vessel speed was known, Laist et al. (2001) found a
direct relationship between the occurrence of a whale strike and the
speed of the vessel involved in the collision. The authors concluded
that most deaths occurred when a vessel was traveling in excess of 13
kn.
Jensen and Silber (2003) detailed 292 records of known or probable
ship strikes of all large whale species from 1975 to 2002. Of these,
vessel speed at the time of collision was reported for 58 cases. Of
these 58 cases, 39 (or 67 percent) resulted in serious injury or death
(19 of those resulted in serious injury as determined by blood in the
water, propeller gashes or severed tailstock, and fractured skull, jaw,
vertebrae, hemorrhaging, massive bruising or other injuries noted
during necropsy and 20 resulted in death). Operating speeds of vessels
that struck various species of large whales ranged from 2 to 51 kn. The
majority (79 percent) of these strikes occurred at speeds of 13 kn or
greater. The average speed that resulted in serious injury or death was
18.6 kn. Pace and Silber (2005) found that the probability of death or
serious injury increased rapidly with increasing vessel speed.
Specifically, the predicted probability of serious injury or death
increased from 45 to 75 percent as vessel speed increased from 10 to 14
kn, and exceeded 90 percent at 17 kn. Higher speeds during collisions
result in greater force of impact and also appear to increase the
chance of severe injuries or death. While modeling studies have
suggested that hydrodynamic forces pulling whales toward the vessel
hull increase with increasing speed (Clyne, 1999; Knowlton et al.,
1995), this is inconsistent with Silber et al. (2010), which
demonstrated that there is no such relationship (i.e., hydrodynamic
forces are independent of speed).
In a separate study, Vanderlaan and Taggart (2007) analyzed the
probability of lethal mortality of large whales at a given speed,
showing that the greatest rate of change in the probability of a lethal
injury to a large whale as a function of vessel speed occurs between
8.6 and 15 kn. The chances of a lethal injury decline from
approximately 80 percent at 15 kn to approximately 20 percent at 8.6
kn. At speeds below 11.8 kn, the chances of lethal injury drop below 50
percent, while the probability asymptotically increases toward 100
percent above 15 kn.
The Jensen and Silber (2003) report notes that the Large Whale Ship
Strike Database represents a minimum number of collisions, because the
vast majority probably goes undetected or unreported. In contrast, Navy
personnel are likely to detect any strike that does occur because of
the required personnel training and lookouts (as described in the
Proposed Mitigation Measures section), and they are required to report
all ship strikes involving marine mammals.
In the MITT Study Area, NMFS has no documented vessel strikes of
marine mammals by the Navy. This, however, precludes the use of the
quantitative approach to assess the likelihood of vessel strikes used
in the 2018 and 2019 incidental take rulemakings for Navy activities in
the AFTT and HSTT Study Areas, which starts with the number of Navy
strikes that have occurred in the study area in question. Based on this
lack of strikes and other factors described below, which the Navy
presented and NMFS agrees are appropriate factors to consider in
assessing the likelihood of ship strike, the Navy does not anticipate
vessel strikes and has not requested authorization to take marine
mammals by serious injury or mortality within the MITT Study Area
during training and testing activities. NMFS agrees with the Navy's
decision based on the analysis and other factors described below. Table
8 summarizes the factors considered in determining the risk of vessel
strikes on large whales in the MITT Study Area, along with the
associated qualitative scores for each, which are described below. For
species with definite seasonal occurrence (e.g., winter), the approach
assigns a value of +1 for a ``yes'' and +0.5 for a ``no'' answer to
account for the possibility that a species could be there. In the other
columns, the approach assigns a value of +1 for a ``yes'' and -1 for a
``no'' answer. Justification for inclusion of a vessel strike request
was based on whether a final evaluation score was greater than zero
(similar to the analysis in the HSTT rule). None of the final
evaluation scores for large whales were greater than zero. Regardless
of the scoring system the Navy presented, NMFS concurs that the factors
considered are appropriate and that they support a determination that
vessel strike is not likely to occur.
Table 8--Weight of Evidence Approach for Determining the Risk of Vessel Strike on Large Whales in the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Justification
Year-round High Density for including
Species presence? (yes =1/ (>0.001/km\2\)? (yes Stranding record? Ship strike record? Final vessel strike
no = 0.5) =1/no = -1) (yes = 1/no = -1) (yes =1/no = -1) evaluation request (final
evaluation >0)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale.................... no (0.5)............ no (-1)............. no (-1)............. no (-1)............. -2.5 Did not request
vessel strike.
Fin whale..................... no (0.5)............ no (-1)............. no (-1)............. no (-1)............. -2.5 Did not request
vessel strike.
Humpback whale................ no (0.5)............ no (-1)............. no (-1)............. no (-1)............. -2.5 Did not request
vessel strike.
Sei whale..................... no (0.5)............ no (-1)............. no (-1)............. no (-1)............. -2.5 Did not request
vessel strike.
[[Page 5827]]
Sperm whale................... yes (1)............. no (-1)............. yes (1) *........... no (-1)............. 0 Did not request
vessel strike.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Six sperm whale strandings 1962 to 2018.
Additionally, the Navy has fewer vessel transits than commercial
entities and other Federal agencies in the MITT Study Area. For
example, over the five-year period between 2014 and 2018, there were a
total of 8,984 civilian commercial and Federal agency vessel transits
(excluding Navy) through Apra Harbor (Table 9). This represents 86
percent of all vessel transits. The remaining 14 percent were Navy
vessel transits (total of 1,497 transits). Other Federal agency vessels
include NOAA research vessels, U.S. Coast Guard vessels, and Department
of Defense (other than Navy) vessels account for approximately 5
percent of these total transits. The most frequent ship types arriving
at the Jose D. Leon Guerrero Commercial Port were container ships (27
percent), long-line fishing vessels (22 percent), tankers (12 percent),
and break bulk ships (10 percent) (Port of Guam, unpublished data).
These statistics do not account for civilian recreational boats, tour
boats, or personal watercraft (i.e., jet skis). The Navy transits are
about five times less than commercial shipping transits alone. Overall,
the percentage of Navy vessel traffic relative to the commercial and
other Federal agency shipping traffic is much smaller (14 percent), and
therefore represents a correspondingly smaller threat of potential ship
strikes when compared to other vessel use.
Table 9--Commercial and Navy Ship Transits Through Apra Harbor Guam 2014-2018
----------------------------------------------------------------------------------------------------------------
Commercial and other
Year federal agency vessel U.S. Navy vessel Total annual
transits transits transits
----------------------------------------------------------------------------------------------------------------
2014.................................... 1,735..................... 339....................... 2,074
2015.................................... 1,654..................... 328....................... 1,982
2016.................................... 1,534..................... 293....................... 1,827
2017.................................... 2,068..................... 264....................... 2,332
2018.................................... 1,993..................... 273....................... 2,266
-----------------------------------------------------------------------
5-yr Total.......................... 8,984 (86 percent)........ 1,497 (14 percent)........ 10,481
5-yr Average.................... 1,797 (86 percent)........ 299 (14 percent).......... 2,096
----------------------------------------------------------------------------------------------------------------
Outside of the vessel traffic as described above, major commercial
shipping vessels use shipping lanes for transporting goods between
Hawaii, the continental United States, and Asia. Typically, these are
great circle routes based on the most direct path between major
commercial ports. There are no standard commercial routes between Guam
and the United States. There are also commercial shipping routes from
Asia and Japan to the equatorial Pacific and Australia that pass
through larger portions of the Guam and CNMI Economic Exclusive Zones
(EEZ) as well as the MITT Study Area. Across all warfare areas and
activities, 493 days of Navy at-sea time would occur annually in MITT,
three times less than in the HSTT Study Area.
In addition, large Navy vessels (greater than 18 m in length)
within the offshore areas of range complexes and testing ranges operate
differently from commercial vessels in ways that may reduce potential
whale collisions. Surface ships operated by or for the Navy have
multiple personnel assigned to stand watch at all times, when a ship or
surfaced submarine is moving through the water (underway). A primary
duty of personnel standing watch on surface ships is to detect and
report all objects and disturbances sighted in the water that may
indicate a threat to the vessel and its crew, such as debris, a
periscope, surfaced submarine, or surface disturbance. Per vessel
safety requirements, personnel standing watch also report any marine
mammals sighted in the path of the vessel as a standard collision
avoidance procedure. All vessels proceed at a safe speed so they can
take proper and effective action to avoid a collision with any sighted
object or disturbance, and can be stopped within a distance appropriate
to the prevailing circumstances and conditions.
Between 2007 and 2009, the Navy developed and distributed
additional training, mitigation, and reporting tools to Navy operators
to improve marine mammal protection and to ensure compliance with LOA
requirements. In 2009, the Navy implemented Marine Species Awareness
Training designed to improve effectiveness of visual observation for
marine resources, including marine mammals. For over a decade, the Navy
has implemented the Protective Measures Assessment Protocol software
tool, which provides operators with notification of the required
mitigation and a visual display of the planned training or testing
activity location overlaid with relevant environmental data.
Based on all of these considerations, NMFS has preliminarily
determined that the Navy's decision not to request take authorization
for vessel strike of large whales is supported by multiple factors,
including the lack of ship strike reports in regional NMFS stranding
records (1962-2018) for the Mariana Islands (including no strikes by
Navy vessels in the MITT Study Area), the relatively low density of
large marine mammals in the Mariana Islands, and the seasonal nature of
several species (blue whales, humpback whales, fin whales, and sei
whales). In addition, there are relatively small numbers of
[[Page 5828]]
Navy vessels across a large expanse of offshore waters in the MITT
Study Area, and the procedural mitigation measures that would be in
place further minimize potential vessel strike.
In addition to the reasons listed above that make it unlikely that
the Navy will hit a large whale (more maneuverable ships, larger crew,
etc.), the following are additional reasons that vessel strike of
dolphins and small whales is very unlikely. Dating back more than 20
years and for as long as it has kept records, the Navy has no records
of individuals of these groups being struck by a vessel as a result of
Navy activities and, further, their smaller size and maneuverability
make a strike unlikely. Also, NMFS has never received any reports from
other authorized activities indicating that these species have been
struck by vessels. Worldwide ship strike records show little evidence
of strikes of these groups from the shipping sector and larger vessels,
and the majority of the Navy's activities involving faster-moving
vessels (that could be considered more likely to hit a marine mammal)
are located in offshore areas where smaller delphinid densities are
lower. Based on this information, NMFS concurs with the Navy's
assessment that vessel strike is not likely to occur for either large
whales or smaller marine mammals.
Marine Mammal Habitat
The Navy's proposed training and testing activities could
potentially affect marine mammal habitat through the introduction of
impacts to the prey species of marine mammals, acoustic habitat (sound
in the water column), water quality, and important habitat for marine
mammals. Each of these potential effects was considered in the 2019
MITT DSEIS/OEIS and was determined by the Navy to have no effect on
marine mammal habitat. Based on the information below and the
supporting information included in the 2019 MITT DSEIS/OEIS, NMFS has
determined that the proposed training and training activities would not
have adverse or long-term impacts on marine mammal habitat.
Effects to Prey
Sound may affect marine mammals through impacts on the abundance,
behavior, or distribution of prey species (e.g., crustaceans,
cephalopods, fish, zooplankton). Marine mammal prey varies by species,
season, and location and, for some, is not well documented. Here, we
describe studies regarding the effects of noise on known marine mammal
prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
The most likely effects on fishes exposed to loud, intermittent, low-
frequency sounds are behavioral responses (i.e., flight or avoidance).
Short duration, sharp sounds (such as pile driving or air guns) can
cause overt or subtle changes in fish behavior and local distribution.
The reaction of fish to acoustic sources depends on the physiological
state of the fish, past exposures, motivation (e.g., feeding, spawning,
migration), and other environmental factors. Key impacts to fishes may
include behavioral responses, hearing damage, barotrauma (pressure-
related injuries), and mortality.
Fishes, like other vertebrates, have a variety of different sensory
systems to glean information from ocean around them (Astrup and Mohl,
1993; Astrup, 1999; Braun and Grande, 2008; Carroll et al., 2017;
Hawkins and Johnstone, 1978; Ladich and Popper, 2004; Ladich and
Schulz-Mirbach, 2016; Mann, 2016; Nedwell et al., 2004; Popper et al.,
2003; Popper et al., 2005). Depending on their hearing anatomy and
peripheral sensory structures, which vary among species, fishes hear
sounds using pressure and particle motion sensitivity capabilities and
detect the motion of surrounding water (Fay et al., 2008) (terrestrial
vertebrates generally only detect pressure). Most marine fishes
primarily detect particle motion using the inner ear and lateral line
system, while some fishes possess additional morphological adaptations
or specializations that can enhance their sensitivity to sound
pressure, such as a gas-filled swim bladder (Braun and Grande, 2008;
Popper and Fay, 2011).
Hearing capabilities vary considerably between different fish
species with data only available for just over 100 species out of the
34,000 marine and freshwater fish species (Eschmeyer and Fong, 2016).
In order to better understand acoustic impacts on fishes, fish hearing
groups are defined by species that possess a similar continuum of
anatomical features which result in varying degrees of hearing
sensitivity (Popper and Hastings, 2009a). There are four hearing groups
defined for all fish species (modified from Popper et al., 2014) within
this analysis and they include: Fishes without a swim bladder (e.g.,
flatfish, sharks, rays, etc.); fishes with a swim bladder not involved
in hearing (e.g., salmon, cod, pollock, etc.); fishes with a swim
bladder involved in hearing (e.g., sardines, anchovy, herring, etc.);
and fishes with a swim bladder involved in hearing and high-frequency
hearing (e.g., shad and menhaden). Most marine mammal fish prey species
would not be likely to perceive or hear Navy mid- or high-frequency
sonars. While hearing studies have not been done on sardines and
northern anchovies, it would not be unexpected for them to have hearing
similarities to Pacific herring (up to 2-5 kHz) (Mann et al., 2005).
Currently, less data are available to estimate the range of best
sensitivity for fishes without a swim bladder.
In terms of physiology, multiple scientific studies have documented
a lack of mortality or physiological effects to fish from exposure to
low- and mid-frequency sonar and other sounds (Halvorsen et al., 2012;
J[oslash]rgensen et al., 2005; Juanes et al., 2017; Kane et al., 2010;
Kvadsheim and Sevaldsen, 2005; Popper et al., 2007; Popper et al.,
2016; Watwood et al., 2016). Techer et al. (2017) exposed carp in
floating cages for up to 30 days to low-power 23 and 46 kHz source
without any significant physiological response. Other studies have
documented either a lack of TTS in species whose hearing range cannot
perceive Navy sonar, or for those species that could perceive sonar-
like signals, any TTS experienced would be recoverable (Halvorsen et
al., 2012; Ladich and Fay, 2013; Popper and Hastings, 2009a, 2009b;
Popper et al., 2014; Smith, 2016). Only fishes that have
specializations that enable them to hear sounds above about 2,500 Hz
(2.5 kHz) such as herring (Halvorsen et al., 2012; Mann et al., 2005;
Mann, 2016; Popper et al., 2014) would have the potential to receive
TTS or exhibit behavioral responses from exposure to mid-frequency
sonar. In addition, any sonar induced TTS to fish whose hearing range
could perceive sonar would only occur in the narrow spectrum of the
source (e.g., 3.5 kHz) compared to the fish's total hearing range
(e.g., 0.01 kHz to 5 kHz). Overall, Navy sonar sources are much
narrower in terms of source frequency compared to a given fish species
full hearing range (Halvorsen et al., 2012; J[oslash]rgensen et al.,
2005; Juanes et al., 2017; Kane et al., 2010; Kvadsheim & Sevaldsen,
2005; Popper et al., 2007; Popper and Hawkins, 2016; Watwood et al.,
2016).
In terms of behavioral responses, Juanes et al. (2017) discuss the
potential for negative impacts from anthropogenic soundscapes on fish,
but the author's focus was on broader based sounds such as ship and
boat noise sources. Watwood et al. (2016) also documented no behavioral
responses by reef fish after exposure to mid-frequency active sonar.
Doksaeter et al. (2009; 2012)
[[Page 5829]]
reported no behavioral responses to mid-frequency naval sonar by
Atlantic herring; specifically, no escape reactions (vertically or
horizontally) were observed in free swimming herring exposed to mid-
frequency sonar transmissions. Based on these results (Doksaeter et
al., 2009; Doksaeter et al., 2012; Sivle et al., 2012), Sivle et al.
(2014) created a model in order to report on the possible population-
level effects on Atlantic herring from active naval sonar. The authors
concluded that the use of naval sonar poses little risk to populations
of herring regardless of season, even when the herring populations are
aggregated and directly exposed to sonar. Finally, Bruintjes et al.
(2016) commented that fish exposed to any short-term noise within their
hearing range might initially startle, but would quickly return to
normal behavior.
Occasional behavioral reactions to intermittent explosions and
impulsive sound sources are unlikely to cause long-term consequences
for individual fish or populations. Fish that experience hearing loss
as a result of exposure to explosions and impulsive sound sources may
have a reduced ability to detect relevant sounds such as predators,
prey, or social vocalizations. However, PTS has not been known to occur
in fishes and any hearing loss in fish may be as temporary as the
timeframe required to repair or replace the sensory cells that were
damaged or destroyed (Popper et al., 2005; Popper et al., 2014; Smith
et al., 2006). It is not known if damage to auditory nerve fibers could
occur, and if so, whether fibers would recover during this process. It
is also possible for fish to be injured or killed by an explosion in
the immediate vicinity of the surface from dropped or fired ordnance,
or near the bottom from shallow water bottom-placed underwater mine
warfare detonations. Physical effects from pressure waves generated by
underwater sounds (e.g., underwater explosions) could potentially
affect fish within proximity of training or testing activities. The
shock wave from an underwater explosion is lethal to fish at close
range, causing massive organ and tissue damage and internal bleeding
(Keevin and Hempen, 1997). At greater distance from the detonation
point, the extent of mortality or injury depends on a number of factors
including fish size, body shape, orientation, and species (Keevin and
Hempen, 1997; Wright, 1982). At the same distance from the source,
larger fish are generally less susceptible to death or injury,
elongated forms that are round in cross-section are less at risk than
deep-bodied forms, and fish oriented sideways to the blast suffer the
greatest impact (Edds-Walton and Finneran, 2006; O'Keeffe, 1984;
O'Keeffe and Young, 1984; Wiley et al., 1981; Yelverton et al., 1975).
Species with gas-filled organs are more susceptible to injury and
mortality than those without them (Gaspin, 1975; Gaspin et al., 1976;
Goertner et al., 1994). Barotrauma injuries have been documented during
controlled exposure to impact pile driving (an impulsive noise source,
as are explosives and air guns) (Halvorsen et al., 2012b; Casper et
al., 2013).
Fish not killed or driven from a location by an explosion might
change their behavior, feeding pattern, or distribution. Changes in
behavior of fish have been observed as a result of sound produced by
explosives, with effect intensified in areas of hard substrate (Wright,
1982). However, Navy explosive use avoids hard substrate to the best
extent practical during underwater detonations, or deep-water surface
detonations (distance from bottom). Stunning from pressure waves could
also temporarily immobilize fish, making them more susceptible to
predation. The abundances of various fish (and invertebrates) near the
detonation point for explosives could be altered for a few hours before
animals from surrounding areas repopulate the area. However, these
populations would likely be replenished as waters near the detonation
point are mixed with adjacent waters. Repeated exposure of individual
fish to sounds from underwater explosions is not likely and are
expected to be short-term and localized. Long-term consequences for
fish populations would not be expected. Several studies have
demonstrated that air gun sounds might affect the distribution and
behavior of some fishes, potentially impacting foraging opportunities
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012;
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999;
Paxton et al., 2017).
For fishes exposed to Navy sonar, there would be limited sonar use
spread out in time and space across large offshore areas such that only
small areas are actually ensonified (10's of miles) compared to the
total life history distribution of fish prey species. There would be no
probability for mortality or physical injury from sonar, and for most
species, no or little potential for hearing or behavioral effects,
except to a few select fishes with hearing specializations (e.g.,
herring) that could perceive mid-frequency sonar. Training and testing
exercises involving explosions are dispersed in space and time;
therefore, repeated exposure of individual fishes are unlikely.
Mortality and injury effects to fishes from explosives would be
localized around the area of a given in-water explosion, but only if
individual fish and the explosive (and immediate pressure field) were
co-located at the same time. Fishes deeper in the water column or on
the bottom would not be affected by water surface explosions. Repeated
exposure of individual fish to sound and energy from underwater
explosions is not likely given fish movement patterns, especially
schooling prey species. Most acoustic effects, if any, are expected to
be short-term and localized. Long-term consequences for fish
populations including key prey species within the MITT Study Area would
not be expected.
Invertebrates appear to be able to detect sounds (Pumphrey, 1950;
Frings and Frings, 1967) and are most sensitive to low-frequency sounds
(Packard et al., 1990; Budelmann and Williamson, 1994; Lovell et al.,
2005; Mooney et al., 2010). Data on response of invertebrates such as
squid, another marine mammal prey species, to anthropogenic sound is
more limited (de Soto, 2016; Sole et al., 2017b). Data suggest that
cephalopods are capable of sensing the particle motion of sounds and
detect low frequencies up to 1-1.5 kHz, depending on the species, and
so are likely to detect air gun noise (Kaifu et al., 2008; Hu et al.,
2009; Mooney et al., 2010; Samson et al., 2014). Sole et al. (2017b)
reported physiological injuries to cuttlefish in cages placed at-sea
when exposed during a controlled exposure experiment to low-frequency
sources (315 Hz, 139 to 142 dB re 1 [mu]Pa\2\ and 400 Hz, 139 to 141 dB
re 1 [mu]Pa\2\). Fewtrell and McCauley (2012) reported squids
maintained in cages displayed startle responses and behavioral changes
when exposed to seismic air gun sonar (136-162 re 1
[mu]Pa\2\[middot]s). However, the sources Sole et al. (2017a) and
Fewtrell and McCauley (2012) used are not similar and were much lower
than typical Navy sources within the MITT Study Area. Nor do the
studies address the issue of individual displacement outside of a zone
of impact when exposed to sound. Cephalopods have a specialized sensory
organ inside the head called a statocyst that may help an animal
determine its position in space (orientation) and maintain balance
(Budelmann, 1992). Packard et al. (1990) showed that cephalopods were
sensitive to particle motion, not sound pressure, and Mooney et al.
(2010) demonstrated that squid statocysts act as an accelerometer
through which
[[Page 5830]]
particle motion of the sound field can be detected. Auditory injuries
(lesions occurring on the statocyst sensory hair cells) have been
reported upon controlled exposure to low-frequency sounds, suggesting
that cephalopods are particularly sensitive to low-frequency sound
(Andre et al., 2011; Sole et al., 2013). Behavioral responses, such as
inking and jetting, have also been reported upon exposure to low-
frequency sound (McCauley et al., 2000b; Samson et al., 2014). Squids,
like most fish species, are likely more sensitive to low frequency
sounds, and may not perceive mid- and high-frequency sonars such as
Navy sonars. Cumulatively for squid as a prey species, individual and
population impacts from exposure to Navy sonar and explosives, like
fish, are not likely to be significant, and explosive impacts would be
short-term and localized.
Explosions could kill or injure nearby marine invertebrates.
Vessels also have the potential to impact marine invertebrates by
disturbing the water column or sediments, or directly striking
organisms (Bishop, 2008). The propeller wash (water displaced by
propellers used for propulsion) from vessel movement and water
displaced from vessel hulls can potentially disturb marine
invertebrates in the water column and is a likely cause of zooplankton
mortality (Bickel et al., 2011). The localized and short-term exposure
to explosions or vessels could displace, injure, or kill zooplankton,
invertebrate eggs or larvae, and macro-invertebrates. However,
mortality or long-term consequences for a few animals is unlikely to
have measurable effects on overall populations. Long-term consequences
to marine invertebrate populations would not be expected as a result of
exposure to sounds or vessels in the MITT Study Area.
Vessels and in-water devices do not normally collide with adult
fish, most of which can detect and avoid them. Exposure of fishes to
vessel strike stressors is limited to those fish groups that are large,
slow-moving, and may occur near the surface, such as ocean sunfish,
whale sharks, basking sharks, and manta rays. These species are
distributed widely in offshore portions of the MITT Study Area. Any
isolated cases of a Navy vessel striking an individual could injure
that individual, impacting the fitness of an individual fish. Vessel
strikes would not pose a risk to most of the other marine fish groups,
because many fish can detect and avoid vessel movements, making strikes
rare and allowing the fish to return to their normal behavior after the
ship or device passes. As a vessel approaches a fish, they could have a
detectable behavioral or physiological response (e.g., swimming away
and increased heart rate) as the passing vessel displaces them.
However, such reactions are not expected to have lasting effects on the
survival, growth, recruitment, or reproduction of these marine fish
groups at the population level and therefore would not have an impact
on marine mammals species as prey items.
In addition to fish, prey sources such as marine invertebrates
could potentially be impacted by sound stressors as a result of the
proposed activities. However, most marine invertebrates' ability to
sense sounds is very limited. In most cases, marine invertebrates would
not respond to impulsive and non-impulsive sounds, although they may
detect and briefly respond to nearby low-frequency sounds. These short-
term responses would likely be inconsequential to invertebrate
populations. Impacts to benthic communities from impulsive sound
generated by active acoustic sound sources are not well documented.
(e.g., Andriguetto-Filho et al., 2005; Payne et al., 2007; 2008;
Boudreau et al., 2009). There are no published data that indicate
whether temporary or permanent threshold shifts, auditory masking, or
behavioral effects occur in benthic invertebrates (Hawkins et al.,
2014) and some studies showed no short-term or long-term effects of air
gun exposure (e.g., Andriguetto-Filho et al., 2005; Payne et al., 2007;
2008; Boudreau et al., 2009). Exposure to air gun signals was found to
significantly increase mortality in scallops, in addition to causing
significant changes in behavioral patterns during exposure (Day et al.,
2017). However, the authors state that the observed levels of mortality
were not beyond naturally occurring rates. Explosions and pile driving
could potentially kill or injure nearby marine invertebrates; however,
mortality or long-term consequences for a few animals is unlikely to
have measurable effects on overall populations.
Vessels also have the potential to impact marine invertebrates by
disturbing the water column or sediments, or directly striking
organisms (Bishop, 2008). The propeller wash from vessel movement and
water displaced from vessel hulls can potentially disturb marine
invertebrates in the water column and is a likely cause of zooplankton
mortality (Bickel et al., 2011). The localized and short-term exposure
to explosions or vessels could displace, injure, or kill zooplankton,
invertebrate eggs or larvae, and macro-invertebrates. However,
mortality or long-term consequences for a few animals is unlikely to
have measurable effects on overall populations.
There is little information concerning potential impacts of noise
on zooplankton populations. However, one recent study (McCauley et al.,
2017) investigated zooplankton abundance, diversity, and mortality
before and after exposure to air gun noise, finding that the exposure
resulted in significant depletion for more than half the taxa present
and that there were two to three times more dead zooplankton after air
gun exposure compared with controls for all taxa. The majority of taxa
present were copepods and cladocerans; for these taxa, the range within
which effects on abundance were detected was up to approximately 1.2
km. In order to have significant impacts on r-selected species such as
plankton, the spatial or temporal scale of impact must be large in
comparison with the ecosystem concerned (McCauley et al., 2017).
Therefore, the large scale of effect observed here is of concern--
particularly where repeated noise exposure is expected--and further
study is warranted.
Overall, the combined impacts of sound exposure, explosions, vessel
strikes, and military expended materials resulting from the proposed
activities would not be expected to have measurable effects on
populations of marine mammal prey species. Prey species exposed to
sound might move away from the sound source, experience TTS, experience
masking of biologically relevant sounds, or show no obvious direct
effects. Mortality from decompression injuries is possible in close
proximity to a sound, but only limited data on mortality in response to
air gun noise exposure are available (Hawkins et al., 2014). The most
likely impacts for most prey species in a given area would be temporary
avoidance of the area. Surveys using towed air gun arrays move through
an area relatively quickly, limiting exposure to multiple impulsive
sounds. In all cases, sound levels would return to ambient once a
survey ends and the noise source is shut down and, when exposure to
sound ends, behavioral and/or physiological responses are expected to
end relatively quickly (McCauley et al., 2000b). The duration of fish
avoidance of a given area after survey effort stops is unknown, but a
rapid return to normal recruitment, distribution, and behavior is
anticipated. While the potential for disruption of spawning
aggregations or schools of important prey species can be meaningful on
a local scale, the mobile
[[Page 5831]]
and temporary nature of most surveys and the likelihood of temporary
avoidance behavior suggest that impacts would be minor. Long-term
consequences to marine invertebrate populations would not be expected
as a result of exposure to sounds or vessels in the MITT Study Area.
Military expended materials resulting from training and testing
activities could potentially result in minor long-term changes to
benthic habitat. Military expended materials may be colonized over time
by benthic organisms that prefer hard substrate and would provide
structure that could attract some species of fish or invertebrates.
Acoustic Habitat
Acoustic habitat is the soundscape which encompasses all of the
sound present in a particular location and time, as a whole when
considered from the perspective of the animals experiencing it. Animals
produce sound for, or listen for sounds produced by, conspecifics
(communication during feeding, mating, and other social activities),
other animals (finding prey or avoiding predators), and the physical
environment (finding suitable habitats, navigating). Together, sounds
made by animals and the geophysical environment (e.g., produced by
earthquakes, lightning, wind, rain, waves) make up the natural
contributions to the total acoustics of a place. These acoustic
conditions, termed acoustic habitat, are one attribute of an animal's
total habitat.
Soundscapes are also defined by, and acoustic habitat influenced
by, the total contribution of anthropogenic sound. This may include
incidental emissions from sources such as vessel traffic or may be
intentionally introduced to the marine environment for data acquisition
purposes (as in the use of air gun arrays) or for Navy training and
testing purposes (as in the use of sonar and explosives and other
acoustic sources). Anthropogenic noise varies widely in its frequency,
content, duration, and loudness and these characteristics greatly
influence the potential habitat-mediated effects to marine mammals
(please also see the previous discussion on ``Masking''), which may
range from local effects for brief periods of time to chronic effects
over large areas and for long durations. Depending on the extent of
effects to habitat, animals may alter their communications signals
(thereby potentially expending additional energy) or miss acoustic cues
(either conspecific or adventitious). Problems arising from a failure
to detect cues are more likely to occur when noise stimuli are chronic
and overlap with biologically relevant cues used for communication,
orientation, and predator/prey detection (Francis and Barber, 2013).
For more detail on these concepts see, e.g., Barber et al., 2009;
Pijanowski et al., 2011; Francis and Barber, 2013; Lillis et al., 2014.
The term ``listening area'' refers to the region of ocean over
which sources of sound can be detected by an animal at the center of
the space. Loss of communication space concerns the area over which a
specific animal signal, used to communicate with conspecifics in
biologically important contexts (e.g., foraging, mating), can be heard,
in noisier relative to quieter conditions (Clark et al., 2009). Lost
listening area concerns the more generalized contraction of the range
over which animals would be able to detect a variety of signals of
biological importance, including eavesdropping on predators and prey
(Barber et al., 2009). Such metrics do not, in and of themselves,
document fitness consequences for the marine animals that live in
chronically noisy environments. Long-term population-level consequences
mediated through changes in the ultimate survival and reproductive
success of individuals are difficult to study, and particularly so
underwater. However, it is increasingly well documented that aquatic
species rely on qualities of natural acoustic habitats, with
researchers quantifying reduced detection of important ecological cues
(e.g., Francis and Barber, 2013; Slabbekoorn et al., 2010) as well as
survivorship consequences in several species (e.g., Simpson et al.,
2014; Nedelec et al., 2015).
Sound produced from training and testing activities in the MITT
Study Area is temporary and transitory. The sounds produced during
training and testing activities can be widely dispersed or concentrated
in small areas for varying periods. Any anthropogenic noise attributed
to training and testing activities in the MITT Study Area would be
temporary and the affected area would be expected to immediately return
to the original state when these activities cease.
Water Quality
The 2019 MITT DSEIS/OEIS analyzed the potential effects on water
quality from military expended materials. Training and testing
activities may introduce water quality constituents into the water
column. Based on the analysis of the 2019 MITT DSEIS/OEIS, military
expended materials (e.g., undetonated explosive materials) would be
released in quantities and at rates that would not result in a
violation of any water quality standard or criteria. High-order
explosions consume most of the explosive material, creating typical
combustion products. For example, in the case of Royal Demolition
Explosive, 98 percent of the products are common seawater constituents
and the remainder is rapidly diluted below threshold effect level.
Explosion by-products associated with high order detonations present no
secondary stressors to marine mammals through sediment or water.
However, low order detonations and unexploded ordnance present elevated
likelihood of impacts on marine mammals.
Indirect effects of explosives and unexploded ordnance to marine
mammals via sediment is possible in the immediate vicinity of the
ordnance. Degradation products of Royal Demolition Explosive are not
toxic to marine organisms at realistic exposure levels (Rosen and
Lotufo, 2010). Relatively low solubility of most explosives and their
degradation products means that concentrations of these contaminants in
the marine environment are relatively low and readily diluted.
Furthermore, while explosives and their degradation products were
detectable in marine sediment approximately 6-12 in (0.15-0.3 m) away
from degrading ordnance, the concentrations of these compounds were not
statistically distinguishable from background beyond 3-6 ft (1-2 m)
from the degrading ordnance. Taken together, it is possible that marine
mammals could be exposed to degrading explosives, but it would be
within a very small radius of the explosive (1-6 ft (0.3-2 m)).
Equipment used by the Navy within the MITT Study Area, including
ships and other marine vessels, aircraft, and other equipment, are also
potential sources of by-products. All equipment is properly maintained
in accordance with applicable Navy and legal requirements. All such
operating equipment meets Federal water quality standards, where
applicable.
Estimated Take of Marine Mammals
This section indicates the number of takes that NMFS is proposing
to authorize, which are based on the maximum amount of take that NMFS
anticipates is reasonably expected to occur. NMFS coordinated closely
with the Navy in the development of their incidental take application,
and preliminarily agrees that the methods the Navy has put forth
described herein to estimate take (including the model, thresholds, and
density estimates), and the resulting numbers are based on the best
available science and appropriate for authorization.
[[Page 5832]]
Takes would be in the form of harassment only. For military
readiness activities, the MMPA defines ``harassment'' as (i) Any act
that injures or has the significant potential to injure a marine mammal
or marine mammal stock in the wild (Level A harassment); or (ii) Any
act that disturbs or is likely to disturb a marine mammal or marine
mammal stock in the wild by causing disruption of natural behavioral
patterns, including, but not limited to, migration, surfacing, nursing,
breeding, feeding, or sheltering, to a point where such behavioral
patterns are abandoned or significantly altered (Level B harassment).
Proposed authorized takes would primarily be in the form of Level B
harassment, as use of the acoustic and explosive sources (i.e., sonar
and explosives) is more likely to result in behavioral disruption
(rising to the level of a take as described above) or temporary
threshold shift (TTS) for marine mammals than other forms of take.
There is also the potential for Level A harassment, however, in the
form of auditory injury and/or tissue damage (the latter from
explosives only) to result from exposure to the sound sources utilized
in training and testing activities.
Generally speaking, for acoustic impacts NMFS estimates the amount
and type of harassment by considering: (1) Acoustic thresholds above
which NMFS believes the best available science indicates marine mammals
will be taken by Level B harassment (in this case, as defined in the
military readiness definition of Level B harassment included above) or
incur some degree of temporary or permanent hearing impairment; (2) the
area or volume of water that will be ensonified above these levels in a
day or event; (3) the density or occurrence of marine mammals within
these ensonified areas; and (4) the number of days of activities or
events.
Acoustic Thresholds
Using the best available science, NMFS, in coordination with the
Navy, has established acoustic thresholds that identify the most
appropriate received level of underwater sound above which marine
mammals exposed to these sound sources could be reasonably expected to
experience a disruption in behavior patterns to a point where they are
abandoned or significantly altered, or to incur TTS (equated to Level B
harassment) or PTS of some degree (equated to Level A harassment).
Thresholds have also been developed to identify the pressure levels
above which animals may incur non-auditory injury from exposure to
pressure waves from explosive detonation.
Despite the quickly evolving science, there are still challenges in
quantifying expected behavioral responses that qualify as take by Level
B harassment, especially where the goal is to use one or two
predictable indicators (e.g., received level and distance) to predict
responses that are also driven by additional factors that cannot be
easily incorporated into the thresholds (e.g., context). So, while the
behavioral Level B harassment thresholds have been refined here to
better consider the best available science (e.g., incorporating both
received level and distance), they also still have some built-in
conservative factors to address the challenge noted. For example, while
duration of observed responses in the data are now considered in the
thresholds, some of the responses that are informing take thresholds
are of a very short duration, such that it is possible some of these
responses might not always rise to the level of disrupting behavior
patterns to a point where they are abandoned or significantly altered.
We describe the application of this Level B harassment threshold as
identifying the maximum number of instances in which marine mammals
could be reasonably expected to experience a disruption in behavior
patterns to a point where they are abandoned or significantly altered.
In summary, we believe these behavioral Level B harassment thresholds
are the most appropriate method for predicting behavioral Level B
harassment given the best available science and the associated
uncertainty.
Hearing Impairment (TTS/PTS and Tissues Damage and Mortality)
Non-Impulsive and Impulsive
NMFS' Acoustic Technical Guidance (NMFS, 2018) identifies dual
criteria to assess auditory injury (Level A harassment) to five
different marine mammal groups (based on hearing sensitivity) as a
result of exposure to noise from two different types of sources
(impulsive or non-impulsive). The Acoustic Technical Guidance also
identifies criteria to predict TTS, which is not considered injury and
falls into the Level B harassment category. The Navy's planned activity
includes the use of non-impulsive (sonar) and impulsive (explosives)
sources.
These thresholds (Tables 10 and 11) were developed by compiling and
synthesizing the best available science and soliciting input multiple
times from both the public and peer reviewers. The references,
analysis, and methodology used in the development of the thresholds are
described in Acoustic Technical Guidance, which may be accessed at:
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
Table 10--Acoustic Thresholds Identifying the Onset of TTS and PTS for
Non-Impulsive Sound Sources by Functional Hearing Groups
------------------------------------------------------------------------
Non-impulsive
-------------------------------
Functional hearing group TTS threshold PTS threshold
SEL SEL
(weighted) (weighted)
------------------------------------------------------------------------
Low-Frequency Cetaceans................. 179 199
Mid-Frequency Cetaceans................. 178 198
High-Frequency Cetaceans................ 153 173
Phocid Pinnipeds (Underwater)........... 181 201
Otarid Pinnipeds (Underwater)........... 199 219
------------------------------------------------------------------------
Note: SEL thresholds in dB re 1 [mu]Pa\2\s.
Based on the best available science, the Navy (in coordination with
NMFS) used the acoustic and pressure thresholds indicated in Table 11
to predict the onset of TTS, PTS, tissue damage, and mortality for
explosives (impulsive) and other impulsive sound sources.
[[Page 5833]]
Table 11--Onset of TTS, PTS, Tissue Damage, and Mortality Thresholds for Marine Mammals for Explosives and Other Impulsive Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mean onset
Functional hearing group Species Onset TTS Onset PTS Mean onset slight slight lung Mean onset
GI tract injury injury mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-frequency cetaceans......... All mysticetes..... 168 dB SEL 183 dB SEL 237 dB Peak SPL.... Equation 1...... Equation 2.
(weighted) or 213 (weighted) or 219
dB Peak SPL. dB Peak SPL.
Mid-frequency cetaceans......... Most delphinids, 170 dB SEL 185 dB SEL 237 dB Peak SPL....
medium and large (weighted) or 224 (weighted) or 230
toothed whales. dB Peak SPL. dB Peak SPL.
High-frequency cetaceans........ Porpoises and Kogia 140 dB SEL 155 dB SEL 237 dB Peak SPL....
spp.. (weighted) or 196 (weighted) or 202
dB Peak SPL. dB Peak SPL.
Phocidae........................ Harbor seal, 170 dB SEL 185 dB SEL 237 dB Peak SPL....
Hawaiian monk (weighted) or 212 (weighted) or 218
seal, Northern dB Peak SPL. dB Peak SPL.
elephant seal.
Otariidae....................... California sea 188 dB SEL 203 dB SEL 237 dB Peak SPL....
lion, Guadalupe (weighted) or 226 (weighted) or 232
fur seal, Northern dB Peak SPL. dB Peak SPL.
fur seal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Equation 1: 47.5M 1/3 (1+[DRm/10.1]) 1/6 Pa-sec. Equation 2: 103M 1/3 (1+[D>Rm/10.1]) 1/6 Pa-sec. M = mass of the animals in kg; DRm = depth of
the receiver (animal) in meters; SPL = sound pressure level.
The criteria used to assess the onset of TTS and PTS due to
exposure to sonars (non-impulsive, see Table 10 above) are discussed
further in the Navy's rulemaking/LOA application (see Hearing Loss from
Sonar and Other Transducers in Chapter 6, Section 6.4.2.1, Methods for
Analyzing Impacts from Sonars and Other Transducers). Refer to the
Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects
Analysis (Phase III) report (U.S. Department of the Navy, 2017c) for
detailed information on how the criteria and thresholds were derived.
Non-auditory injury (i.e., other than PTS) and mortality from sonar and
other transducers is so unlikely as to be discountable under normal
conditions for the reasons explained under the Potential Effects of
Specified Activities on Marine Mammals and Their Habitat section--
Acoustically Mediated Bubble Growth and other Pressure-related Injury
and is therefore not considered further in this analysis.
Behavioral Harassment
Though significantly driven by received level, the onset of Level B
harassment by behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source (e.g., frequency, predictability, duty cycle), the environment
(e.g., bathymetry), and the receiving animals (hearing, motivation,
experience, demography, behavioral context) and can be difficult to
predict (Ellison et al., 2011; Southall et al., 2007). Based on what
the available science indicates and the practical need to use
thresholds based on a factor, or factors, that are both predictable and
measurable for most activities, NMFS uses generalized acoustic
thresholds based primarily on received level (and distance in some
cases) to estimate the onset of Level B behavioral harassment.
Sonar
As noted above, the Navy coordinated with NMFS to develop, and
propose for use in this rule, Level B behavioral harassment thresholds
specific to their military readiness activities utilizing active sonar.
These behavioral response thresholds are used to estimate the number of
animals that may exhibit a behavioral response that rises to the level
of a take when exposed to sonar and other transducers. The way the
criteria were derived is discussed in detail in the Criteria and
Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase
III) report (U.S. Department of the Navy, 2017c). Developing the Level
B harassment behavioral criteria involved multiple steps. All peer-
reviewed published behavioral response studies conducted both in the
field and on captive animals were examined in order to understand the
breadth of behavioral responses of marine mammals to sonar and other
transducers. NMFS has carefully reviewed the Navy's Level B behavioral
thresholds and establishment of cutoff distances for the species, and
agrees that it is the best available science and is the appropriate
method to use at this time for determining impacts to marine mammals
from sonar and other transducers and for calculating take and to
support the determinations made in this proposed rule.
As discussed above, marine mammal responses to sound (some of which
are considered disturbances that rise to the level of a take) are
highly variable and context specific, i.e., they are affected by
differences in acoustic conditions; differences between species and
populations; differences in gender, age, reproductive status, or social
behavior; or other prior experience of the individuals. This means that
there is support for considering alternative approaches for estimating
Level B behavioral harassment. Although the statutory definition of
Level B harassment for military readiness activities means that a
natural behavior pattern of a marine mammal is significantly altered or
abandoned, the current state of science for determining those
thresholds is somewhat unsettled.
In its analysis of impacts associated with sonar acoustic sources
(which was coordinated with NMFS), the Navy used an updated
conservative approach that likely overestimates the number of takes by
Level B harassment due to behavioral disturbance and response. Many of
the behavioral responses identified using the Navy's quantitative
analysis are most likely to be of moderate severity as described in the
Southall et al. (2007) behavioral response severity scale. These
``moderate'' severity responses were considered significant if they
were sustained for the duration of the exposure or longer. Within the
Navy's quantitative analysis, many reactions are predicted from
exposure to sound that may exceed an animal's Level B behavioral
harassment threshold for only a single exposure (a few seconds) to
several minutes, and it is likely that some of the resulting estimated
behavioral responses that are counted as Level B harassment would not
constitute ``significantly altering or abandoning natural behavioral
patterns.'' The Navy and NMFS have used the best available science to
address the challenging differentiation between significant and non-
significant behavioral reactions (i.e., whether the behavior has been
abandoned or significantly altered such that it qualifies as
harassment), but have erred on the cautious side where uncertainty
[[Page 5834]]
exists (e.g., counting these lower duration reactions as take), which
likely results in some degree of overestimation of Level B behavioral
harassment. We consider application of this Level B behavioral
harassment threshold, therefore, as identifying the maximum number of
instances in which marine mammals could be reasonably expected to
experience a disruption in behavior patterns to a point where they are
abandoned or significantly altered (i.e., Level B harassment). Because
this is the most appropriate method for estimating Level B harassment
given the best available science and uncertainty on the topic, it is
these numbers of Level B harassment by behavioral disturbance that are
analyzed in the Preliminary Analysis and Negligible Impact
Determination section and would be authorized.
In the Navy's acoustic impact analyses during Phase II (previous
phase of Navy testing and training, 2013-2018, see also Navy's Criteria
and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis
Technical Report, 2012), the likelihood of Level B behavioral
harassment in response to sonar and other transducers was based on a
probabilistic function (termed a behavioral response function--BRF),
that related the likelihood (i.e., probability) of a behavioral
response (at the level of a Level B harassment) to the received SPL.
The BRF was used to estimate the percentage of an exposed population
that is likely to exhibit Level B harassment due to altered behaviors
or behavioral disturbance at a given received SPL. This BRF relied on
the assumption that sound poses a negligible risk to marine mammals if
they are exposed to SPL below a certain ``basement'' value. Above the
basement exposure SPL, the probability of a response increased with
increasing SPL. Two BRFs were used in Navy acoustic impact analyses:
BRF1 for mysticetes and BRF2 for other species. BRFs were not used for
beaked whales during Phase II analyses. Instead, a step function at an
SPL of 140 dB re 1 [mu]Pa was used for beaked whales as the threshold
to predict Level B harassment by behavioral disturbance.
Developing the Level B behavioral harassment criteria for Phase III
(the current phase of Navy training and testing activities) involved
multiple steps: All available behavioral response studies conducted
both in the field and on captive animals were examined to understand
the breadth of behavioral responses of marine mammals to sonar and
other transducers (See also Navy's Criteria and Thresholds for U.S.
Navy Acoustic and Explosive Effects Analysis (Phase III) Technical
Report, 2017). Six behavioral response field studies with observations
of 14 different marine mammal species reactions to sonar or sonar-like
signals and 6 captive animal behavioral studies with observations of 8
different species reactions to sonar or sonar-like signals were used to
provide a robust data set for the derivation of the Navy's Phase III
marine mammal behavioral response criteria. All behavioral response
research that has been published since the derivation of the Navy's
Phase III criteria (c.a. December 2016) has been examined and is
consistent with the current behavioral response functions. Marine
mammal species were placed into behavioral criteria groups based on
their known or suspected behavioral sensitivities to sound. In most
cases these divisions were driven by taxonomic classifications (e.g.,
mysticetes, pinnipeds). The data from the behavioral studies were
analyzed by looking for significant responses, or lack thereof, for
each experimental session.
The Navy used cutoff distances beyond which the potential of
significant behavioral responses (and therefore Level B harassment) is
considered to be unlikely (see Table 12 below). This was determined by
examining all available published field observations of behavioral
reactions to sonar or sonar-like signals that included the distance
between the sound source and the marine mammal. The longest distance,
rounded up to the nearest 5-km increment, was chosen as the cutoff
distance for each behavioral criteria group (i.e. odontocetes,
mysticetes, and beaked whales). For animals within the cutoff distance,
a behavioral response function based on a received SPL as presented in
Chapter 3, Section 3.1.0 of the Navy's rulemaking/LOA application was
used to predict the probability of a potential significant behavioral
response. For training and testing events that contain multiple
platforms or tactical sonar sources that exceed 215 dB re 1 [mu]Pa @1
m, this cutoff distance is substantially increased (i.e., doubled) from
values derived from the literature. The use of multiple platforms and
intense sound sources are factors that probably increase responsiveness
in marine mammals overall (however, we note that helicopter dipping
sonars were considered in the intense sound source group, despite lower
source levels, because of data indicating that marine mammals are
sometimes more responsive to the less predictable employment of this
source). There are currently few behavioral observations under these
circumstances; therefore, the Navy conservatively predicted significant
behavioral responses that would rise to Level B harassment at farther
ranges as shown in Table 12, versus less intense events.
Table 12--Cutoff Distances for Moderate Source Level, Single Platform
Training and Testing Events and for All Other Events With Multiple
Platforms or Sonar With Source Levels at or Exceeding 215 dB re 1
[micro]Pa @1 m
------------------------------------------------------------------------
Moderate SL/single High SL/multi-
Criteria group platform cutoff platform cutoff
distance distance
------------------------------------------------------------------------
Odontocetes................. 10 km............... 20 km.
Mysticetes.................. 10 km............... 20 km.
Beaked Whales............... 25 km............... 50 km.
------------------------------------------------------------------------
Note: dB re 1 [micro]Pa @1 m: Decibels referenced to 1 micropascal at 1
meter; km: Kilometer; SL: Source level.
The range to received sound levels in 6-dB steps from five
representative sonar bins and the percentage of animals that may be
taken by Level B harassment under each behavioral response function are
shown in Table 13 through Table 17. Cells are shaded if the mean range
value for the specified received level exceeds the distance cutoff
range for a particular hearing group and therefore are not included in
the estimated take. See Chapter 6, Section 6.4.2.1.1 (Methods for
Analyzing Impacts from Sonars and Other Transducers) of the Navy's
rulemaking/LOA application for further details on the derivation and
use of the behavioral response functions,
[[Page 5835]]
thresholds, and the cutoff distances to identify takes by Level B
harassment, which were coordinated with NMFS. Table 13 illustrates the
maximum likely percentage of exposed individuals taken at the indicated
received level and associated range (in which marine mammals would be
reasonably expected to experience a disruption in behavior patterns to
a point where they are abandoned or significantly altered) for LFAS. As
noted previously, NMFS carefully reviewed, and contributed to, the
Navy's proposed Level B behavioral harassment thresholds and cutoff
distances for the species, and agrees that these methods represent the
best available science at this time for determining impacts to marine
mammals from sonar and other transducers.
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[[Page 5837]]
Table 14. Ranges to estimated Level B behavioral harassment takes
for sonar bin MF1 over a representative range of environments within
the MITT Study Area.
[GRAPHIC] [TIFF OMITTED] TP31JA20.003
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[[Page 5840]]
Table 17 identifies the maximum likely percentage of exposed
individuals taken at the indicated received level and associated range
for HFAS.
Table 17--Ranges To Estimated Level B Behavioral Harassment Takes for Sonar Bin HF4 Over a Representative Range
of Environments Within the MITT Study Area
----------------------------------------------------------------------------------------------------------------
Probability of level B behavioral harassment
Average range (m) with for sonar Bin HF4
Received level (dB re 1 [micro]Pa) minimum and maximum -----------------------------------------------
values in parenthesis Odontocetes Beaked whales
(%) Mysticetes (%) (%)
----------------------------------------------------------------------------------------------------------------
196.................................... 3 (2-4) 100 100 100
190.................................... 8 (6-10) 100 98 100
184.................................... 16 (12-20) 99 88 100
178.................................... 32 (24-40) 97 59 100
172.................................... 63 (45-80) 91 30 99
166.................................... 120 (75-160) 78 20 97
160.................................... 225 (120-310) 58 18 93
154.................................... 392 (180-550) 40 17 83
148.................................... 642 (280-1,275) 29 16 66
142.................................... 916 (420-1,775) 25 13 45
136.................................... 1,359 (625-2,525) 23 9 28
130.................................... 1,821 (950-3,275) 20 5 18
124.................................... 2,567 (1,275-5,025) 17 2 14
118.................................... 3,457 (1,775-6,025) 12 1 12
112.................................... 4,269 (2,275-7,025) 6 0 11
106.................................... 5,300 (3,025-8,025) 3 0 11
100.................................... 6,254 (3,775-9,275) 1 0 8
----------------------------------------------------------------------------------------------------------------
Notes: dB re 1 [micro]Pa = decibels referenced to 1 micropascal, m = meters.
Explosives
Phase III explosive criteria for Level B behavioral harassment
thresholds for marine mammals is the hearing groups' TTS threshold
minus 5 dB (see Table 18 below and Table 11 for the TTS thresholds for
explosives) for events that contain multiple impulses from explosives
underwater. This was the same approach as taken in Phase II for
explosive analysis. See the Criteria and Thresholds for U.S. Navy
Acoustic and Explosive Effects Analysis (Phase III) report (U.S.
Department of the Navy, 2017c) for detailed information on how the
criteria and thresholds were derived. NMFS continues to concur that
this approach represents the best available science for determining
impacts to marine mammals from explosives.
Table 18--Level B Behavioral Harassment Thresholds for Explosives for
Marine Mammals
------------------------------------------------------------------------
Functional hearing
Medium group SEL (weighted)
------------------------------------------------------------------------
Underwater........................ LF.................. 163
Underwater........................ MF.................. 165
Underwater........................ HF.................. 135
------------------------------------------------------------------------
Note: Weighted SEL thresholds in dB re 1 [mu]Pa\2\s underwater.
Navy's Acoustic Effects Model
The Navy's Acoustic Effects Model calculates sound energy
propagation from sonar and other transducers and explosives during
naval activities and the sound received by animat dosimeters. Animat
dosimeters are virtual representations of marine mammals distributed in
the area around the modeled naval activity and each dosimeter records
its individual sound ``dose.'' The model bases the distribution of
animats over the MITT Study Area on the density values in the Navy
Marine Species Density Database and distributes animats in the water
column proportional to the known time that species spend at varying
depths.
The model accounts for environmental variability of sound
propagation in both distance and depth when computing the received
sound level received by the animats. The model conducts a statistical
analysis based on multiple model runs to compute the estimated effects
on animals. The number of animats that exceed the thresholds for
effects is tallied to provide an estimate of the number of marine
mammals that could be affected.
Assumptions in the Navy model intentionally err on the side of
overestimation when there are unknowns. Naval activities are modeled as
though they would occur regardless of proximity to marine mammals,
meaning that no mitigation is considered (i.e., no power down or shut
down modeled) and without any avoidance of the activity by the animal.
The final step of the quantitative analysis of acoustic effects is to
consider the implementation of mitigation and the possibility that
marine mammals would avoid continued or repeated sound exposures. For
more information on this process, see the discussion in the Take
Requests subsection below. Many explosions from ordnance such as bombs
and missiles actually occur upon impact with above-water targets.
However, for this analysis, sources such as these were modeled as
exploding underwater. This overestimates the amount of explosive and
acoustic energy entering the water.
The model estimates the impacts caused by individual training and
testing exercises. During any individual modeled event, impacts to
individual animats are considered over 24-hour periods. The animats do
not represent actual animals, but rather they represent a distribution
of animals based on density and abundance data, which allows for a
statistical analysis of the number of instances that marine mammals may
be exposed to sound levels resulting in an effect. Therefore, the model
estimates the number of instances in which an effect threshold was
exceeded over the course of a year, but does not estimate the number of
individual marine mammals that may be impacted over a year (i.e., some
marine mammals could be impacted several times, while others would not
experience any impact). A detailed
[[Page 5841]]
explanation of the Navy's Acoustic Effects Model is provided in the
technical report Quantifying Acoustic Impacts on Marine Mammals and Sea
Turtles: Methods and Analytical Approach for Phase III Training and
Testing report (U.S. Department of the Navy, 2018).
Range to Effects
The following section provides range to effects for sonar and other
active acoustic sources as well as explosives to specific acoustic
thresholds determined using the Navy Acoustic Effects Model. Marine
mammals exposed within these ranges for the shown duration are
predicted to experience the associated effect. Range to effects is
important information in not only predicting acoustic impacts, but also
in verifying the accuracy of model results against real-world
situations and determining adequate mitigation ranges to avoid higher
level effects, especially physiological effects to marine mammals.
Sonar
The range to received sound levels in 6-dB steps from five
representative sonar bins and the percentage of the total number of
animals that may exhibit a significant behavioral response (and
therefore Level B harassment) under each behavioral response function
are shown in Table 13 through Table 17 above, respectively. See Chapter
6, Section 6.4.2.1 (Methods for Analyzing Impacts from Sonars and Other
Transducers) of the Navy's rulemaking/LOA application for additional
details on the derivation and use of the behavioral response functions,
thresholds, and the cutoff distances that are used to identify Level B
behavioral harassment.
The ranges to PTS for five representative sonar systems for an
exposure of 30 seconds is shown in Table 19 relative to the marine
mammal's functional hearing group. This period (30 seconds) was chosen
based on examining the maximum amount of time a marine mammal would
realistically be exposed to levels that could cause the onset of PTS
based on platform (e.g., ship) speed and a nominal animal swim speed of
approximately 1.5 m per second. The ranges provided in the table
include the average range to PTS, as well as the range from the minimum
to the maximum distance at which PTS is possible for each hearing
group.
Table 19--Range to Permanent Threshold Shift (Meters) for Five Representative Sonar Systems
----------------------------------------------------------------------------------------------------------------
Approximate range in meters for PTS from 30 second exposure \1\
Hearing group -------------------------------------------------------------------------------
Sonar bin HF4 Sonar bin LF4 Sonar bin MF1 Sonar bin MF4 Sonar bin MF5
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans........ 29 (22-35) 0 (0-0) 181 (180-190) 30 (30-30) 9 (8-10)
Low-frequency cetaceans......... 0 (0-0) 0 (0-0) 65 (65-65) 15 (15-15) 0 (0-0)
Mid-frequency cetaceans......... 1 (0-1) 0 (0-0) 16 (16-16) 3 (3-3) 0 (0-0)
----------------------------------------------------------------------------------------------------------------
\1\ PTS ranges extend from the sonar or other active acoustic sound source to the indicated distance. The
average range to PTS is provided as well as the range from the estimated minimum to the maximum range to PTS
in parenthesis.
The tables below illustrate the range to TTS for 1, 30, 60, and 120
seconds from five representative sonar systems (see Table 20 through
Table 24).
Table 20--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin LF4 Over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Approximate TTS ranges (meters) \1\
---------------------------------------------------------------------------------------------------
Hearing group Sonar Bin LF4
---------------------------------------------------------------------------------------------------
1 second 30 seconds 60 seconds 120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................ 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0)
Low-frequency cetaceans............................. 3 (3-3) 4 (4-4) 6 (6-6) 9 (9-9)
Mid-frequency cetaceans............................. 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT Study Area. The zone in which animals are expected to
suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to
the maximum range to TTS in parentheses.
Table 21--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF1 Over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Approximate TTS ranges (meters) \1\
---------------------------------------------------------------------------------------------------
Hearing group Sonar Bin MF1
---------------------------------------------------------------------------------------------------
1 second 30 seconds 60 seconds 120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................ 3,181 (2,025-5,025) 3,181 (2,025-5,025) 5,298 (2,275-7,775) 6,436 (2,525-9,775)
Low-frequency cetaceans............................. 898 (850-1,025) 898 (850-1,025) 1,271 (1,025-1,525) 1,867 (1,275-3,025)
Mid-frequency cetaceans............................. 210 (200-210) 210 (200-210) 302 (300-310) 377 (370-390)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT Study Area. The zone in which animals are expected to
suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to
the maximum range to TTS in parentheses.
Note: Ranges for 1-second and 30-second periods are identical for Bin MF1 because this system nominally pings every 50 seconds; therefore, these periods
encompass only a single ping.
[[Page 5842]]
Table 22--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF4 Over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Approximate TTS ranges (meters) \1\
---------------------------------------------------------------------------------------------------
Hearing group Sonar Bin MF4
---------------------------------------------------------------------------------------------------
1 second 30 seconds 60 seconds 120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................ 232 (220-260) 454 (420-600) 601 (575-875) 878 (800-1,525)
Low-frequency cetaceans............................. 85 (85-90) 161 (160-170) 229 (220-250) 352 (330-410)
Mid-frequency cetaceans............................. 22 (22-22) 35 (35-35) 50 (45-50) 70 (70-70)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT Study Area. The zone in which animals are expected to
suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to
the maximum range to TTS in parentheses.
Table 23-- Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF5 Over a Representative Range of Environments Within the MITT Study Area.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Approximate TTS ranges (meters) \1\
---------------------------------------------------------------------------------------------------
Hearing group Sonar Bin MF5
---------------------------------------------------------------------------------------------------
1 second 30 seconds 60 seconds 120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................ 114 (110-130) 114 (110-130) 168 (150-200) 249 (210-290)
Low-frequency cetaceans............................. 11 (10-12) 11 (10-12) 16 (16-17) 23 (23-24)
Mid-frequency cetaceans............................. 5 (0-9) 5 (0-9) 12 (11-13) 18 (17-18)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT Study Area. The zone in which animals are expected to
suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to
the maximum range to TTS in parentheses.
Table 24--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin HF4 over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Approximate TTS ranges (meters) \1\
---------------------------------------------------------------------------------------------------
Hearing group Sonar Bin HF4
---------------------------------------------------------------------------------------------------
1 second 30 seconds 60 seconds 120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................ 155 (110-210) 259 (180-350) 344 (240-480) 445 (300-600)
Low-frequency cetaceans............................. 1 (0-2) 2 (1-3) 4 (3-5) 7 (5-8)
Mid-frequency cetaceans............................. 10 (7-12) 17 (12-21) 24 (17-30) 33 (25-40)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT Study Area. The zone in which animals are expected to
suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to
the maximum range to TTS in parentheses.
Explosives
The following section provides the range (distance) over which
specific physiological or behavioral effects are expected to occur
based on the explosive criteria (see Chapter 6, Section 6.5.2.1.1 of
the Navy's rulemaking/LOA application and the Criteria and Thresholds
for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)
report (U.S. Department of the Navy, 2017c)) and the explosive
propagation calculations from the Navy Acoustic Effects Model (see
Chapter 6, Section 6.5.2.1.3, Navy Acoustic Effects Model of the Navy's
rulemaking/LOA application). The range to effects are shown for a range
of explosive bins, from E1 (up to 0.25 lb net explosive weight) to E12
(up to 1,000 lb net explosive weight) (Tables 25 through 29). Ranges
are determined by modeling the distance that noise from an explosion
would need to propagate to reach exposure level thresholds specific to
a hearing group that would cause behavioral response (to the degree of
Level B behavioral harassment), TTS, PTS, and non-auditory injury.
Ranges are provided for a representative source depth and cluster size
for each bin. For events with multiple explosions, sound from
successive explosions can be expected to accumulate and increase the
range to the onset of an impact based on SEL thresholds. Ranges to non-
auditory injury and mortality are shown in Tables 28 and 29,
respectively. NMFS has reviewed the range distance to effect data
provided by the Navy and concurs with the analysis. Range to effects is
important information in not only predicting impacts from explosives,
but also in verifying the accuracy of model results against real-world
situations and determining adequate mitigation ranges to avoid higher
level effects, especially physiological effects to marine mammals. For
additional information on how ranges to impacts from explosions were
estimated, see the technical report Quantifying Acoustic Impacts on
Marine Mammals and Sea Turtles: Methods and Analytical Approach for
Phase III Training and Testing (U.S. Navy, 2018).
Table 25 shows the minimum, average, and maximum ranges to onset of
auditory and likely behavioral effects that rise to the level of Level
B harassment for high-frequency cetaceans based on the developed
thresholds.
[[Page 5843]]
Table 25--SEL-Based Ranges (Meters) to Onset PTS, Onset TTS, and Level B Behavioral Harassment for High-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Range to effects for explosives bin: High-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
Source Cluster
Bin depth (m) size PTS TTS Behavioral
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1................................................. 0.1 1 353 (340-370) 1,303 (1,275-1,775) 2,139 (2,025-4,275)
........... 18 1,031 (1,025-1,275) 3,409 (2,525-8,025) 4,208 (3,025-11,525)
E2................................................. 0.1 1 431 (410-700) 1,691 (1,525-2,775) 2,550 (2,025-4,525)
........... 5 819 (775-1,275) 2,896 (2,275-6,775) 3,627 (2,525-10,275)
E3................................................. 0.1 1 649 (625-700) 2,439 (2,025-4,525) 3,329 (2,525-7,525)
........... 12 1,682 (1,525-2,275) 4,196 (3,025-11,525) 5,388 (4,525-16,275)
18.25 1 720 (675-775) 4,214 (2,275-6,275) 7,126 (3,525-8,775)
........... 12 1,798 (1,525-2,775) 10,872 (4,525-13,775) 14,553 (5,525-17,775)
E4................................................. 10 2 1,365 (1,025-2,775) 7,097 (4,275-10,025) 9,939 (5,025-15,275)
60 2 1,056 (875-2,275) 3,746 (2,775-5,775) 5,262 (3,025-7,775)
E5................................................. 0.1 20 2,926 (1,525-6,275) 6,741 (4,525-16,025) 9,161 (4,775-20,025)
30 20 4,199 (3,025-6,275) 13,783 (8,775-17,775) 17,360 (10,525-22,775)
E6................................................. 0.1 1 1,031 (1,025-1,275) 3,693 (2,025-8,025) 4,659 (3,025-12,775)
30 1 1,268 (1,025-1,275) 7,277 (3,775-8,775) 10,688 (5,275-12,525)
E7................................................. 28 1 1,711 (1,525-2,025) 8,732 (4,275-11,775) 12,575 (4,275-16,025)
E8................................................. 0.1 1 1,790 (1,775-3,025) 4,581 (4,025-10,775) 6,028 (4,525-15,775)
45.75 1 1,842 (1,525-2,025) 9,040 (4,525-12,775) 12,729 (5,025-18,525)
E9................................................. 0.1 1 2,343 (2,275-4,525) 5,212 (4,025-13,275) 7,573 (5,025-17,025)
E10................................................ 0.1 1 2,758 (2,275-5,025) 6,209 (4,275-16,525) 8,578 (5,275-19,775)
E11................................................ 45.75 1 3,005 (2,525-3,775) 11,648 (5,025-18,775) 14,912 (6,525-24,775)
91.4 1 3,234 (2,525-4,525) 5,772 (4,775-11,775) 7,197 (5,775-14,025)
E12................................................ 0.1 1 3,172 (3,025-6,525) 7,058 (5,025-17,025) 9,262 (6,025-21,775)
........... 4 4,209 (3,775-10,025) 9,817 (6,275-22,025) 12,432 (7,525-27,775)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values
depict the range produced by SEL hearing threshold criteria levels.
Table 26 shows the minimum, average, and maximum ranges to onset of
auditory and likely behavioral effects that rise to the level of Level
B harassment for mid-frequency cetaceans based on the developed
thresholds.
Table 26--SEL-Based Ranges (Meters) to Onset PTS, Onset TTS, and Level B Behavioral Harassment for Mid-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Range to effects for explosives bin: Mid-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
Source Cluster
Bin depth (m) size PTS TTS Behavioral
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1................................................. 0.1 1 25 (25-25) 116 (110-120) 199 (190-210)
........... 18 94 (90-100) 415 (390-440) 646 (525-700)
E2................................................. 0.1 1 30 (30-35) 146 (140-170) 248 (230-370)
........... 5 63 (60-70) 301 (280-410) 481 (430-675)
E3................................................. 0.1 1 50 (50-50) 233 (220-250) 381 (360-400)
........... 12 155 (150-160) 642 (525-700) 977 (700-1,025)
18.25 1 40 (40-40) 202 (190-220) 332 (320-350)
........... 12 126 (120-130) 729 (675-775) 1,025 (1,025-1,025)
E4................................................. 10 2 76 (70-90) 464 (410-550) 783 (650-975)
60 2 60 (60-60) 347 (310-675) 575 (525-900)
E5................................................. 0.1 20 290 (280-300) 1,001 (750-1,275) 1,613 (925-3,275)
30 20 297 (240-420) 1,608 (1,275-2,775) 2,307 (2,025-2,775)
E6................................................. 0.1 1 98 (95-100) 430 (400-450) 669 (550-725)
30 1 78 (75-80) 389 (370-410) 619 (600-650)
E7................................................. 28 1 110 (110-110) 527 (500-575) 1,025 (1,025-1,025)
E8................................................. 0.1 1 162 (150-170) 665 (550-700) 982 (725-1,025)
45.75 1 127 (120-130) 611 (600-625) 985 (950-1,025)
E9................................................. 0.1 1 215 (210-220) 866 (625-1,000) 1,218 (800-1,525)
E10................................................ 0.1 1 270 (250-280) 985 (700-1,275) 1,506 (875-2,525)
E11................................................ 45.75 1 241 (230-250) 1,059 (1,000-1,275) 1,874 (1,525-2,025)
91.4 1 237 (230-270) 1,123 (900-2,025) 1,731 (1,275-2,775)
E12................................................ 0.1 1 332 (320-370) 1,196 (825-1,525) 1,766 (1,025-3,525)
........... 4 572 (500-600) 1,932 (1,025-4,025) 2,708 (1,275-6,775)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values
depict the range produced by SEL hearing threshold criteria levels.
[[Page 5844]]
Table 27 shows the minimum, average, and maximum ranges to onset of
auditory and likely behavioral effects that rise to the level of Level
B harassment for low-frequency cetaceans based on the developed
thresholds.
Table 27--SEL-Based Ranges (Meters) to Onset PTS, Onset TTS, and Level B Behavioral Harassment for Low-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Range to effects for explosives bin: Low-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
Source Cluster
Bin depth (m) size PTS TTS Behavioral
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1................................................. 0.1 1 51 (50-55) 231 (200-250) 378 (280-410)
........... 18 183 (170-190) 691 (450-775) 934 (575-1,275)
E2................................................. 0.1 1 66 (65-70) 291 (220-320) 463 (330-500)
........... 5 134 (110-140) 543 (370-600) 769 (490-950)
E3................................................. 0.1 1 113 (110-120) 477 (330-525) 689 (440-825)
........... 12 327 (250-370) 952 (600-1,525) 1,240 (775-4,025)
18.25 1 200 (200-200) 955 (925-1,000) 1,534 (1,275-1,775)
........... 12 625 (600-625) 5,517 (2,275-7,775) 10,299 (3,775-13,025)
E4................................................. 10 2 429 (370-600) 2,108 (1,775-2,775) 4,663 (3,025-6,025)
60 2 367 (340-470) 1,595 (1,025-2,025) 2,468 (1,525-4,275)
E5................................................. 0.1 20 702 (380-1,275) 1,667 (850-11,025) 2,998 (1,025-19,775)
30 20 1,794 (1,275-2,775) 8,341 (3,775-11,525) 13,946 (4,025-22,275)
E6................................................. 0.1 1 250 (190-410) 882 (480-1,775) 1,089 (625-6,525)
30 1 495 (490-500) 2,315 (2,025-2,525) 5,446 (3,275-6,025)
E7................................................. 28 1 794 (775-900) 4,892 (2,775-6,275) 9,008 (3,775-12,525)
E8................................................. 0.1 1 415 (270-725) 1,193 (625-4,275) 1,818 (825-8,525)
45.75 1 952 (900-975) 6,294 (3,025-9,525) 12,263 (4,275-20,025)
E9................................................. 0.1 1 573 (320-1,025) 1,516 (725-7,275) 2,411 (950-14,275)
E10................................................ 0.1 1 715 (370-1,525) 2,088 (825-28,275) 4,378 (1,025-32,275)
E11................................................ 45.75 1 1,881 (1,525-2,275) 12,425 (4,275-27,275) 23,054 (7,025-65,275)
91.4 1 1,634 (1,275-2,525) 5,686 (3,775-11,275) 11,618 (5,525-64,275)
E12................................................ 0.1 1 790 (420-2,775) 2,698 (925-25,275) 6,032 (1,025-31,275)
........... 4 1,196 (575-6,025) 6,876 (1,525-31,275) 13,073 (3,775-64,275)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values
depict the range produced by SEL hearing threshold criteria levels.
Table 28 shows the minimum, average, and maximum ranges due to
varying propagation conditions to non-auditory injury as a function of
animal mass and explosive bin (i.e., net explosive weight). Ranges to
gastrointestinal tract injury typically exceed ranges to slight lung
injury; therefore, the maximum range to effect is not mass-dependent.
Animals within these water volumes would be expected to receive minor
injuries at the outer ranges, increasing to more substantial injuries,
and finally mortality as an animal approaches the detonation point.
Table 28--Ranges \1\ to 50 Percent Non-Auditory Injury Risk for All
Marine Mammal Hearing Groups
------------------------------------------------------------------------
Range (m) (min-
Bin max)
------------------------------------------------------------------------
E1.................................................... 12 (11-13)
E2.................................................... 16 (15-16)
E3.................................................... 25 (25-25)
E4.................................................... 30 (30-35)
E5.................................................... 40 (40-65)
E6.................................................... 52 (50-60)
E7.................................................... 120 (120-120)
E8.................................................... 98 (90-150)
E9.................................................... 123 (120-270)
E10................................................... 155 (150-430)
E11................................................... 418 (410-420)
E12................................................... 195 (180-675)
------------------------------------------------------------------------
\1\ Distances in meters (m). Average distance is shown with the minimum
and maximum distances due to varying propagation environments in
parentheses.
Note: All ranges to non-auditory injury within this table are driven by
gastrointestinal tract injury thresholds regardless of animal mass.
Ranges to mortality, based on animal mass, are shown in Table 29
below.
Table 29--Ranges \1\ to 50 Percent Mortality Risk for All Marine Mammal Hearing Groups as a Function of Animal Mass
--------------------------------------------------------------------------------------------------------------------------------------------------------
Range to mortality (meters) for various animal mass intervals (kg) \1\
Bin -----------------------------------------------------------------------------------------------
10 250 1,000 5,000 25,000 72,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1...................................................... 3 (3-3) 1 (0-2) 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0)
E2...................................................... 4 (3-4) 2 (1-3) 1 (0-1) 0 (0-0) 0 (0-0) 0 (0-0)
E3...................................................... 9 (7-10) 4 (2-8) 2 (1-2) 1 (0-1) 0 (0-0) 0 (0-0)
E4...................................................... 13 (12-15) 7 (4-12) 3 (3-4) 2 (1-3) 1 (1-1) 1 (0-1)
E5...................................................... 13 (12-30) 7 (4-25) 3 (2-7) 2 (1-5) 1 (1-2) 1 (0-2)
E6...................................................... 16 (15-25) 9 (5-23) 4 (3-8) 3 (2-6) 1 (1-2) 1 (1-2)
E7...................................................... 55 (55-55) 26 (18-40) 13 (11-15) 9 (7-10) 4 (4-4) 3 (2-3)
E8...................................................... 42 (25-65) 22 (9-50) 11 (6-19) 8 (4-13) 4 (2-6) 3 (1-5)
E9...................................................... 33 (30-35) 20 (13-30) 10 (9-12) 7 (5-9) 4 (3-4) 3 (2-3)
[[Page 5845]]
E10..................................................... 55 (40-170) 24 (16-35) 13 (11-15) 9 (7-11) 5 (4-5) 4 (3-4)
E11..................................................... 206 (200-210) 98 (55-170) 44 (35-50) 30 (25-35) 16 (14-18) 12 (10-15)
E12..................................................... 86 (50-270) 35 (20-210) 16 (13-19) 11 (9-13) 6 (5-6) 5 (4-5)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (m) to mortality is depicted above the minimum and maximum distances, which are in parentheses.
Marine Mammal Density
A quantitative analysis of impacts on a species or stock requires
data on their abundance and distribution that may be affected by
anthropogenic activities in the potentially impacted area. The most
appropriate metric for this type of analysis is density, which is the
number of animals present per unit area. Marine species density
estimation requires a significant amount of effort to both collect and
analyze data to produce a reasonable estimate. Unlike surveys for
terrestrial wildlife, many marine species spend much of their time
submerged, and are not easily observed. In order to collect enough
sighting data to make reasonable density estimates, multiple
observations are required, often in areas that are not easily
accessible (e.g., far offshore). Ideally, marine mammal species
sighting data would be collected for the specific area and time period
(e.g., season) of interest and density estimates derived accordingly.
However, in many places, poor weather conditions and high sea states
prohibit the completion of comprehensive visual surveys.
For most cetacean species, abundance is estimated using line-
transect surveys or mark-recapture studies (e.g., Barlow, 2010; Barlow
and Forney, 2007; Calambokidis et al., 2008). The result provides one
single density estimate value for each species across broad geographic
areas. This is the general approach applied in estimating cetacean
abundance in NMFS' Stock Assessment Reports (SARs). Although the single
value provides a good average estimate of abundance (total number of
individuals) for a specified area, it does not provide information on
the species distribution or concentrations within that area, and it
does not estimate density for other timeframes or seasons that were not
surveyed. More recently, spatial habitat modeling developed by NMFS'
Southwest Fisheries Science Center has been used to estimate cetacean
densities (Barlow et al., 2009; Becker et al., 2010, 2012a, b, c, 2014,
2016; Ferguson et al., 2006a; Forney et al., 2012, 2015; Redfern et
al., 2006). These models estimate cetacean density as a continuous
function of habitat variables (e.g., sea surface temperature, seafloor
depth, etc.) and thus allow predictions of cetacean densities on finer
spatial scales than traditional line-transect or mark recapture
analyses and for areas that have not been surveyed. Within the
geographic area that was modeled, densities can be predicted wherever
these habitat variables can be measured or estimated.
Ideally, density data would be available for all species throughout
the study area year-round, in order to best estimate the impacts of
Navy activities on marine species. However, in many places, ship
availability, lack of funding, inclement weather conditions, and high
sea states prevent the completion of comprehensive year-round surveys.
Even with surveys that are completed, poor conditions may result in
lower sighting rates for species that would typically be sighted with
greater frequency under favorable conditions. Lower sighting rates
preclude having an acceptably low uncertainty in the density estimates.
A high level of uncertainty, indicating a low level of confidence in
the density estimate, is typical for species that are rare or difficult
to sight. In areas where survey data are limited or non-existent, known
or inferred associations between marine habitat features and the likely
presence of specific species are sometimes used to predict densities in
the absence of actual animal sightings. Consequently, there is no
single source of density data for every area, species, and season
because of the fiscal costs, resources, and effort involved in
providing enough survey coverage to sufficiently estimate density.
To characterize marine species density for large oceanic regions,
the Navy reviews, critically assesses, and prioritizes existing density
estimates from multiple sources, requiring the development of a
systematic method for selecting the most appropriate density estimate
for each combination of species, area, and season. The selection and
compilation of the best available marine species density data resulted
in the Navy Marine Species Density Database (NMSDD). NMFS vetted all
cetacean densities by the Navy prior to use in the Navy's acoustic
analysis for the current MITT rulemaking process.
In the MITT Study Area there is a paucity of line-transect survey
data, and little is known about the stock structure of the majority of
marine mammal species in the region. The Navy conducted the first
comprehensive marine mammal survey of waters off Guam and the
Commonwealth of the Northern Mariana Islands in 2007, and data from
this survey were used to derive line-transect abundance estimates for
12 cetacean species (Fulling et al., 2011). There has not been a
subsequent systematic survey of the MITT Study Area at this scale, so
these data still provide the best available density estimates for this
region.
In the absence of study-area-specific density data, line-transect
estimates derived for Hawaiian waters were used to provide conservative
density estimates for the MITT Study Area. For Phase II, these
estimates were based on systematic surveys conducted by NMFS' Southwest
Fisheries Science Center (SWFSC) within the Exclusive Economic Zone of
the Hawaiian Islands in 2002 (Barlow, 2006). New survey data collected
within the Exclusive Economic Zone of the Hawaiian Islands (2010) and
Palmyra Atoll/Kingman Reef (2011-2012) allowed NMFS' Pacific Islands
Fisheries Science Center (PIFSC) to update the line-transect density
estimates that included new sea-state-specific estimates of trackline
detection probability (Bradford et al., 2017) and represent
improvements to the estimates used for Phase II. In addition, an
updated density estimate for minke whale was available for Phase III
based on line-transect analyses of acoustic data collected from a towed
hydrophone during the 2007 systematic survey (Norris et al., 2017).
Finally, a habitat model was developed for sperm whale based on
acoustic data collected during the 2007 survey, and provided spatially
explicit density predictions at a10 km x 10 km (100 square km) spatial
resolution (Yack et al., 2016).
[[Page 5846]]
To characterize the marine species density for large areas,
including the MITT Study Area, the Navy compiled data from several
sources. The Navy developed a protocol to select the best available
data sources based on species, area, and time (season). The resulting
Geographic Information System database, used in the NMSDD, includes
seasonal density values for every marine mammal species present within
the MITT Study Area. This database is described in the technical report
titled U.S. Navy Marine Species Density Database Phase III for the
Mariana Islands Training and Testing Study Area (U.S. Department of the
Navy, 2018), hereafter referred to as the Density Technical Report.
A variety of density data and density models are needed in order to
develop a density database that encompasses the entirety of the MITT
Study Area. Because this data is collected using different methods with
varying amounts of accuracy and uncertainty, the Navy has developed a
hierarchy to ensure the most accurate data is used when available. The
Density Technical Report describes these models in detail and provides
detailed explanations of the models applied to each species density
estimate. The list below describes models in order of preference.
1. Spatial density models are preferred and used when available
because they provide an estimate with the least amount of uncertainty
by deriving estimates for divided segments of the sampling area. These
models (see Becker et al., 2016; Forney et al., 2015) predict spatial
variability of animal presence as a function of habitat variables
(e.g., sea surface temperature, seafloor depth, etc.). This model is
developed for areas, species, and, when available, specific timeframes
(months or seasons) with sufficient survey data; therefore, this model
cannot be used for species with low numbers of sightings.
2. Stratified design-based density estimates use line-transect
survey data with the sampling area divided (stratified) into sub-
regions, and a density is predicted for each sub-region (see Barlow,
2016; Becker et al., 2016; Bradford et al., 2017; Campbell et al.,
2014; Jefferson et al., 2014). While geographically stratified density
estimates provide a better indication of a species' distribution within
the study area, the uncertainty is typically high because each sub-
region estimate is based on a smaller stratified segment of the overall
survey effort.
3. Design-based density estimations use line-transect survey data
from land and aerial surveys designed to cover a specific geographic
area (see Carretta et al., 2015). These estimates use the same survey
data as stratified design-based estimates, but are not segmented into
sub-regions and instead provide one estimate for a large surveyed area.
Although relative environmental suitability (RES) models provide
estimates for areas of the oceans that have not been surveyed using
information on species occurrence and inferred habitat associations and
have been used in past density databases, these models were not used in
the current quantitative analysis.
The Navy describes some of the challenges of interpreting the
results of the quantitative analysis summarized above and described in
the Density Technical Report: ``It is important to consider that even
the best estimate of marine species density is really a model
representation of the values of concentration where these animals might
occur. Each model is limited to the variables and assumptions
considered by the original data source provider. No mathematical model
representation of any biological population is perfect, and with
regards to marine mammal biodiversity, any single model method will not
completely explain the actual distribution and abundance of marine
mammal species. It is expected that there would be anomalies in the
results that need to be evaluated, with independent information for
each case, to support if we might accept or reject a model or portions
of the model (U.S. Department of the Navy, 2017a).''
NMFS coordinated with the Navy in the development of its take
estimates and concurs that the Navy's approach for density
appropriately utilizes the best available science. Later, in the
Preliminary Analysis and Negligible Impact Determination section, we
assess how the estimated take numbers compare to abundance in order to
better understand the potential number of individuals impacted, and the
rationale for which abundance estimate is used is included there.
Take Requests
The 2019 MITT DSEIS/OEIS considered all training and testing
activities proposed to occur in the MITT Study Area that have the
potential to result in the MMPA defined take of marine mammals. The
Navy determined that the two stressors below could result in the
incidental taking of marine mammals. NMFS has reviewed the Navy's data
and analysis and determined that it is complete and accurate and agrees
that the following stressors have the potential to result in takes by
harassment of marine mammals from the Navy's planned activities.
[ssquf] Acoustics (sonar and other transducers);
[ssquf] Explosives (explosive shock wave and sound, assumed to
encompass the risk due to fragmentation).
The quantitative analysis process used for the 2019 MITT DSEIS/OEIS
and the Navy's take request in the rulemaking/LOA application to
estimate potential exposures to marine mammals resulting from acoustic
and explosive stressors is detailed in the technical report titled
Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods
and Analytical Approach for Phase III Training and Testing (U.S.
Department of the Navy, 2018). The Navy Acoustic Effects Model
estimates acoustic and explosive effects without taking mitigation into
account; therefore, the model overestimates predicted impacts on marine
mammals within mitigation zones. To account for mitigation for marine
species in the take estimates, the Navy conducts a quantitative
assessment of mitigation. The Navy conservatively quantifies the manner
in which procedural mitigation is expected to reduce the risk for
model-estimated PTS for exposures to sonars and for model-estimated
mortality for exposures to explosives, based on species sightability,
observation area, visibility, and the ability to exercise positive
control over the sound source. Where the analysis indicates mitigation
would effectively reduce risk, the model-estimated PTS are considered
reduced to TTS and the model-estimated mortalities are considered
reduced to injury. For a complete explanation of the process for
assessing the effects of mitigation, see the Navy's rulemaking/LOA
application and the technical report titled Quantifying Acoustic
Impacts on Marine Mammals and Sea Turtles: Methods and Analytical
Approach for Phase III Training and Testing (U.S. Department of the
Navy, 2018). The extent to which the mitigation areas reduce impacts on
the affected species is addressed separately in the Preliminary
Analysis and Negligible Impact Determination section.
The Navy assessed the effectiveness of its procedural mitigation
measures on a per-scenario basis for four factors: (1) Species
sightability, (2) a Lookout's ability to observe the range to PTS (for
sonar and other transducers) and range to mortality (for explosives),
(3) the portion of time when mitigation could potentially be conducted
during periods of reduced daytime visibility (to include inclement
weather and high sea-state) and the portion of time when mitigation
[[Page 5847]]
could potentially be conducted at night, and (4) the ability for sound
sources to be positively controlled (e.g., powered down).
During training and testing activities, there is typically at least
one, if not numerous, support personnel involved in the activity (e.g.,
range support personnel aboard a torpedo retrieval boat or support
aircraft). In addition to the Lookout posted for the purpose of
mitigation, these additional personnel observe and disseminate marine
species sighting information amongst the units participating in the
activity whenever possible as they conduct their primary mission
responsibilities. However, as a conservative approach to assigning
mitigation effectiveness factors, the Navy elected to only account for
the minimum number of required Lookouts used for each activity;
therefore, the mitigation effectiveness factors may underestimate the
likelihood that some marine mammals may be detected during activities
that are supported by additional personnel who may also be observing
the mitigation zone.
The Navy used the equations in the below sections to calculate the
reduction in model-estimated mortality impacts due to implementing
procedural mitigation.
[GRAPHIC] [TIFF OMITTED] TP31JA20.006
Species Sightability is the ability to detect marine mammals and is
dependent on the animal's presence at the surface and the
characteristics of the animal that influence its sightability. The Navy
considered applicable data from the best available science to
numerically approximate the sightability of marine mammals and
determined the standard ``detection probability'' referred to as g(0)
is most appropriate. Also, Visibility = 1-sum of individual visibility
reduction factors; Observation Area = portion of impact range that can
be continuously observed during an event; and Positive Control =
positive control factor of all sound sources involving mitigation. For
further details on these mitigation effectiveness factors please refer
to the technical report titled Quantifying Acoustic Impacts on Marine
Mammals and Sea Turtles: Methods and Analytical Approach for Phase III
Training and Testing (U.S. Department of the Navy, 2018).
To quantify the number of marine mammals predicted to be sighted by
Lookouts in the injury zone during implementation of procedural
mitigation for sonar and other transducers, the species sightability is
multiplied by the mitigation effectiveness scores and number of model-
estimated PTS impacts, as shown in the equation below:
[GRAPHIC] [TIFF OMITTED] TP31JA20.007
The marine mammals sighted by Lookouts in the injury zone during
implementation of mitigation, as calculated by the equation above,
would avoid being exposed to these higher level impacts. To quantify
the number of marine mammals predicted to be sighted by Lookouts in the
mortality zone during implementation of procedural mitigation during
events using explosives, the species sightability is multiplied by the
mitigation effectiveness scores and number of model-estimated mortality
impacts, as shown in equation 1 above. The marine mammals predicted to
be sighted in the mortality zone by Lookouts during implementation of
procedural mitigation, as calculated by the above equation 2, are
predicted to avoid exposure in these ranges. The Navy corrects the
category of predicted impact for the number of animals sighted within
the mitigation zone, but does not modify the total number of animals
predicted to experience impacts from the scenario. For example, the
number of animals sighted (i.e., number of animals that will avoid
mortality) is first subtracted from the model-predicted mortality
impacts, and then added to the model-predicted injurious impacts.
The NAEMO (animal movement) model overestimates the number of
marine mammals that would be exposed to sound sources that could cause
PTS because the model does not consider horizontal movement of animats,
including avoidance of high intensity sound exposures. Therefore, the
potential for animal avoidance is considered separately. At close
ranges and high sound levels, avoidance of the area immediately around
the sound source is one of the assumed behavioral responses for marine
mammals. Animal avoidance refers to the movement out of the immediate
injury zone for subsequent exposures, not wide-scale area avoidance.
Various researchers have demonstrated that cetaceans can perceive the
location and movement of a sound source (e.g., vessel, seismic source,
etc.) relative to their own location and react with responsive movement
away from the source, often at distances of 1 km or more (Au &
Perryman,1982; Jansen et al., 2010; Richardson et al., 1995; Tyack et
al., 2011; Watkins, 1986; W[uuml]rsig et al., 1998) A marine mammal's
ability to avoid a sound source and reduce its cumulative sound energy
exposure would reduce risk of both PTS and TTS. However, the
quantitative analysis conservatively only considers the potential to
reduce some instances of PTS by accounting for marine mammals swimming
away to avoid repeated high-level sound exposures. All reductions in
PTS impacts from likely avoidance behaviors are instead considered TTS
impacts.
[[Page 5848]]
NMFS coordinated with the Navy in the development of this
quantitative method to address the effects of procedural mitigation on
acoustic and explosive exposures and takes, and NMFS independently
reviewed and concurs with the Navy that it is appropriate to
incorporate the quantitative assessment of mitigation into the take
estimates based on the best available science. For additional
information on the quantitative analysis process and mitigation
measures, refer to the technical report titled Quantifying Acoustic
Impacts on Marine Mammals and Sea Turtles: Methods and Analytical
Approach for Phase III Training and Testing (U.S. Department of the
Navy, 2018) and Chapter 6 (Take Estimates for Marine Mammals) and
Chapter 11 (Mitigation Measures) of the Navy's rulemaking/LOA
application.
As a general matter, NMFS does not prescribe the methods for
estimating take for any applicant, but we review and ensure that
applicants use the best available science, and methodologies that are
logical and technically sound. Applicants may use different methods of
calculating take (especially when using models) and still get to a
result that is representative of the best available science and that
allows for a rigorous and accurate evaluation of the effects on the
affected populations. There are multiple pieces of the Navy take
estimation methods--propagation models, animat movement models, and
behavioral thresholds, for example. NMFS evaluates the acceptability of
these pieces as they evolve and are used in different rules and impact
analyses. Some of the pieces of the Navy's take estimation process have
been used in Navy incidental take rules since 2009 and undergone
multiple public comment processes, all of them have undergone extensive
internal Navy review, and all of them have undergone comprehensive
review by NMFS, which has sometimes resulted in modifications to
methods or models.
The Navy uses rigorous review processes (verification, validation,
and accreditation processes, peer and public review) to ensure the data
and methodology it uses represent the best available science. For
instance, the NAEMO model is the result of a NMFS-led Center for
Independent Experts (CIE) review of the components used in earlier
models. The acoustic propagation component of the NAEMO model (CASS/
GRAB) is accredited by the Oceanographic and Atmospheric Master Library
(OAML), and many of the environmental variables used in the NAEMO model
come from approved OAML databases and are based on in-situ data
collection. The animal density components of the NAEMO model are base
products of the NMSDD, which includes animal density components that
have been validated and reviewed by a variety of scientists from NMFS
Science Centers and academic institutions. Several components of the
model, for example the Duke University habitat-based density models,
have been published in peer reviewed literature. Others like the
Atlantic Marine Assessment Program for Protected Species, which was
conducted by NMFS Science Centers, have undergone quality assurance and
quality control (QA/QC) processes. Finally the NAEMO model simulation
components underwent QA/QC review and validation for model parts such
as the scenario builder, acoustic builder, scenario simulator, etc.,
conducted by qualified statisticians and modelers to ensure accuracy.
Other models and methodologies have gone through similar review
processes.
In summary, we believe the Navy's methods, including the method for
incorporating mitigation and avoidance, are the most appropriate
methods for predicting PTS, TTS, and behavioral disruption. But even
with the consideration of mitigation and avoidance, given some of the
more conservative components of the methodology (e.g., the thresholds
do not consider ear recovery between pulses), we would describe the
application of these methods as identifying the maximum number of
instances in which marine mammals would be reasonably expected to be
taken through PTS, TTS, or behavioral disruption.
Summary of Requested Take From Training and Testing Activities
Based on the methods discussed in the previous sections and the
Navy's model and quantitative assessment of mitigation, the Navy
provided its take estimate and request for authorization of takes
incidental to the use of acoustic and explosive sources for training
and testing activities both annually (based on the maximum number of
activities that could occur per 12-month period) and over the seven-
year period covered by the Navy's rulemaking/LOA application. NMFS has
reviewed the Navy's data, methodology, and analysis and determined that
it is complete and accurate. NMFS agrees that the estimates for
incidental takes by harassment from all sources requested for
authorization are the maximum number of instances in which marine
mammals are reasonably expected to be taken.
For training and testing activities, Table 30 summarizes the Navy's
take estimate and request and the annual and maximum amount and type of
Level A harassment and Level B harassment for the seven-year period
that NMFS concurs is reasonably expected to occur by species. Note that
take by Level B harassment includes both behavioral disruption and TTS.
Tables 6.4-13 through 6.4-38 in Section 6 of the Navy's rulemaking/LOA
application provide the comparative amounts of TTS and behavioral
disruption for each species annually, noting that if a modeled marine
mammal was ``taken'' through exposure to both TTS and behavioral
disruption in the model, it was recorded as a TTS.
Table 30--Annual and Seven-Year Total Species-Specific Take Estimates Proposed for Authorization From Acoustic
and Explosive Sound Source Effects for All Training and Testing Activities in the MITT Study Area
----------------------------------------------------------------------------------------------------------------
Annual 7-Year Total \1\
Species ---------------------------------------------------------------
Level B Level A Level B Level A
----------------------------------------------------------------------------------------------------------------
Mysticetes
----------------------------------------------------------------------------------------------------------------
Blue whale *.................................... 24 0 169 0
Bryde's whale................................... 298 0 2,078 0
Fin whale *..................................... 25 0 173 0
Humpback whale *................................ 479 0 3,348 0
Minke whale..................................... 95 0 665 0
Omura's whale................................... 29 0 199 0
[[Page 5849]]
Sei whale *..................................... 155 0 1,083 0
----------------------------------------------------------------------------------------------------------------
Odontocetes
----------------------------------------------------------------------------------------------------------------
Blainville's beaked whale....................... 1,718 0 12,033 0
Bottlenose dolphin.............................. 137 0 961 0
Cuvier's beaked whale........................... 646 0 4,529 0
Dwarf sperm whale............................... 8,499 50 59,459 341
False killer whale.............................. 762 0 5,331 0
Fraser's dolphin................................ 13,278 1 92,931 8
Ginkgo-toothed beaked whale..................... 3,726 0 26,088 0
Killer whale.................................... 44 0 309 0
Longman's beaked whale.......................... 6,066 0 42,487 0
Melon-headed whale.............................. 2,815 0 19,691 0
Pantropical spotted dolphin..................... 14,896 1 104,242 7
Pygmy killer whale.............................. 104 0 726 0
Pygmy sperm whale............................... 3,410 19 23,853 136
Risso's dolphin................................. 3,170 0 22,179 0
Rough-toothed dolphin........................... 197 0 1,379 0
Short-finned pilot whale........................ 1,163 0 8,140 0
Sperm whale *................................... 203 0 1,420 0
Spinner dolphin................................. 1,414 1 9,896 4
Striped dolphin................................. 4,007 0 28,038 0
----------------------------------------------------------------------------------------------------------------
*ESA-listed species within the MITT Study Area
\1\The 7-year totals may be less than the annual totals times seven, given that not all activities occur every
year, some activities occur multiple times within a year, and some activities only occur a few times over the
course of a 7-year period.
Proposed Mitigation Measures
Under section 101(a)(5)(A) of the MMPA, NMFS must set forth the
permissible methods of taking pursuant to the activity, and other means
of effecting the least practicable adverse impact on the species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance, and on the
availability of the species or stocks for subsistence uses (``least
practicable adverse impact''). NMFS does not have a regulatory
definition for least practicable adverse impact. The 2004 NDAA amended
the MMPA as it relates to military readiness activities and the
incidental take authorization process such that a determination of
``least practicable adverse impact'' shall include consideration of
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
In Conservation Council for Hawaii v. National Marine Fisheries
Service, 97 F. Supp.3d 1210, 1229 (D. Haw. 2015), the Court stated that
NMFS ``appear[s] to think [it] satisfies] the statutory `least
practicable adverse impact' requirement with a `negligible impact'
finding.'' More recently, expressing similar concerns in a challenge to
a U.S. Navy Surveillance Towed Array Sensor System Low Frequency Active
Sonar (SURTASS LFA) incidental take rule (77 FR 50290), the Ninth
Circuit Court of Appeals in Natural Resources Defense Council (NRDC) v.
Pritzker, 828 F.3d 1125, 1134 (9th Cir. 2016), stated, ``[c]ompliance
with the `negligible impact' requirement does not mean there [is]
compliance with the `least practicable adverse impact' standard.'' As
the Ninth Circuit noted in its opinion, however, the Court was
interpreting the statute without the benefit of NMFS' formal
interpretation. We state here explicitly that NMFS is in full agreement
that the ``negligible impact'' and ``least practicable adverse impact''
requirements are distinct, even though both statutory standards refer
to species and stocks. With that in mind, we provide further
explanation of our interpretation of least practicable adverse impact,
and explain what distinguishes it from the negligible impact standard.
This discussion is consistent with previous rules we have issued, such
as the Navy's HSTT rule (83 FR 66846; December 27, 2018) and Atlantic
Fleet Training and Testing rule (83 FR 57076; November 14, 2018).
Before NMFS can issue incidental take regulations under section
101(a)(5)(A) of the MMPA, it must make a finding that the total taking
will have a ``negligible impact'' on the affected ``species or stocks''
of marine mammals. NMFS' and U.S. Fish and Wildlife Service's
implementing regulations for section 101(a)(5) both define ``negligible
impact'' as ``an impact resulting from the specified activity that
cannot be reasonably expected to, and is not reasonably likely to,
adversely affect the species or stock through effects on annual rates
of recruitment or survival'' (50 CFR 216.103 and 50 CFR 18.27(c)).
Recruitment (i.e., reproduction) and survival rates are used to
determine population growth rates \1\ and, therefore are considered in
evaluating population level impacts.
---------------------------------------------------------------------------
\1\ A growth rate can be positive, negative, or flat.
---------------------------------------------------------------------------
As stated in the preamble to the proposed rule for the MMPA
incidental take implementing regulations, not every population-level
impact violates the negligible impact requirement. The negligible
impact standard does not require a finding that the anticipated take
will have ``no effect'' on population numbers or growth rates: ``The
statutory standard does not require that the same recovery rate be
maintained, rather that no significant effect on annual rates of
recruitment or survival occurs. [T]he key factor is the significance of
the level of impact on rates of recruitment or survival.'' (54 FR
40338, 40341-42; September 29, 1989).
[[Page 5850]]
While some level of impact on population numbers or growth rates of
a species or stock may occur and still satisfy the negligible impact
requirement--even without consideration of mitigation--the least
practicable adverse impact provision separately requires NMFS to
prescribe means of effecting the least practicable adverse impact on
such species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance,'' 50 CFR
216.102(b), which are typically identified as mitigation measures.\2\
---------------------------------------------------------------------------
\2\ For purposes of this discussion, we omit reference to the
language in the standard for least practicable adverse impact that
says we also must mitigate for subsistence impacts because they are
not at issue in this rule.
---------------------------------------------------------------------------
The negligible impact and least practicable adverse impact
standards in the MMPA both call for evaluation at the level of the
``species or stock.'' The MMPA does not define the term ``species.''
However, Merriam-Webster Dictionary defines ``species'' to include
``related organisms or populations potentially capable of
interbreeding.'' See www.merriam-webster.com/dictionary/species
(emphasis added). Section 3(11) of the MMPA defines ``stock'' as a
group of marine mammals of the same species or smaller taxa in a common
spatial arrangement that interbreed when mature. The definition of
``population'' is a group of interbreeding organisms that represents
the level of organization at which speciation begins. www.merriam-webster.com/dictionary/population. The definition of ``population'' is
strikingly similar to the MMPA's definition of ``stock,'' with both
definitions involving groups of individuals that belong to the same
species and that are located in a manner that allows for interbreeding.
In fact under MMPA section 3(11), the term ``stock'' in the MMPA is
interchangeable with the statutory term ``population stock.'' Both the
negligible impact standard and the least practicable adverse impact
standard call for evaluation at the level of the species or stock, and
the terms ``species'' and ``stock'' both relate to populations;
therefore, it is appropriate to view both the negligible impact
standard and the least practicable adverse impact standard as having a
population-level focus.
This interpretation is consistent with Congress' statutory findings
for enacting the MMPA, nearly all of which are most applicable at the
species or stock (i.e., population) level. See MMPA section 2 (finding
that it is species and population stocks that are or may be in danger
of extinction or depletion; that it is species and population stocks
that should not diminish beyond being significant functioning elements
of their ecosystems; and that it is species and population stocks that
should not be permitted to diminish below their optimum sustainable
population level). Annual rates of recruitment (i.e., reproduction) and
survival are the key biological metrics used in the evaluation of
population-level impacts, and accordingly these same metrics are also
used in the evaluation of population level impacts for the least
practicable adverse impact standard.
Recognizing this common focus of the least practicable adverse
impact and negligible impact provisions on the ``species or stock''
does not mean we conflate the two standards; despite some common
statutory language, we recognize the two provisions are different and
have different functions. First, a negligible impact finding is
required before NMFS can issue an incidental take authorization.
Although it is acceptable to use the mitigation measures to reach a
negligible impact finding (see 50 CFR 216.104(c)), no amount of
mitigation can enable NMFS to issue an incidental take authorization
for an activity that still would not meet the negligible impact
standard. Moreover, even where NMFS can reach a negligible impact
finding--which we emphasize does allow for the possibility of some
``negligible'' population-level impact--the agency must still prescribe
measures that will affect the least practicable amount of adverse
impact upon the affected species or stock.
Section 101(a)(5)(A)(i)(II) requires NMFS to issue, in conjunction
with its authorization, binding--and enforceable--restrictions (in the
form of regulations) setting forth how the activity must be conducted,
thus ensuring the activity has the ``least practicable adverse impact''
on the affected species or stocks. In situations where mitigation is
specifically needed to reach a negligible impact determination, section
101(a)(5)(A)(i)(II) also provides a mechanism for ensuring compliance
with the ``negligible impact'' requirement. Finally, the least
practicable adverse impact standard also requires consideration of
measures for marine mammal habitat, with particular attention to
rookeries, mating grounds, and other areas of similar significance, and
for subsistence impacts, whereas the negligible impact standard is
concerned solely with conclusions about the impact of an activity on
annual rates of recruitment and survival.\3\ In NRDC v. Pritzker, the
Court stated, ``[t]he statute is properly read to mean that even if
population levels are not threatened significantly, still the agency
must adopt mitigation measures aimed at protecting marine mammals to
the greatest extent practicable in light of military readiness needs.''
Pritzker at 1134 (emphases added). This statement is consistent with
our understanding stated above that even when the effects of an action
satisfy the negligible impact standard (i.e., in the Court's words,
``population levels are not threatened significantly''), still the
agency must prescribe mitigation under the least practicable adverse
impact standard. However, as the statute indicates, the focus of both
standards is ultimately the impact on the affected ``species or
stock,'' and not solely focused on or directed at the impact on
individual marine mammals.
---------------------------------------------------------------------------
\3\ Outside of the military readiness context, mitigation may
also be appropriate to ensure compliance with the ``small numbers''
language in MMPA sections 101(a)(5)(A) and (D).
---------------------------------------------------------------------------
We have carefully reviewed and considered the Ninth Circuit's
opinion in NRDC v. Pritzker in its entirety. While the Court's
reference to ``marine mammals'' rather than ``marine mammal species or
stocks'' in the italicized language above might be construed as a
holding that the least practicable adverse impact standard applies at
the individual ``marine mammal'' level, i.e., that NMFS must require
mitigation to minimize impacts to each individual marine mammal unless
impracticable, we believe such an interpretation reflects an incomplete
appreciation of the Court's holding. In our view, the opinion as a
whole turned on the Court's determination that NMFS had not given
separate and independent meaning to the least practicable adverse
impact standard apart from the negligible impact standard, and further,
that the Court's use of the term ``marine mammals'' was not addressing
the question of whether the standard applies to individual animals as
opposed to the species or stock as a whole. We recognize that while
consideration of mitigation can play a role in a negligible impact
determination, consideration of mitigation measures extends beyond that
analysis. In evaluating what mitigation measures are appropriate, NMFS
considers the potential impacts of the Specified Activities, the
availability of measures to minimize those potential impacts, and the
practicability of implementing those measures, as we describe below.
[[Page 5851]]
Implementation of Least Practicable Adverse Impact Standard
Given the NRDC v. Pritzker decision, we discuss here how we
determine whether a measure or set of measures meets the ``least
practicable adverse impact'' standard. Our separate analysis of whether
the take anticipated to result from Navy's activities meets the
``negligible impact'' standard appears in the Preliminary Analysis and
Negligible Impact Determination section below.
Our evaluation of potential mitigation measures includes
consideration of two primary factors:
(1) The manner in which, and the degree to which, implementation of
the potential measure(s) is expected to reduce adverse impacts to
marine mammal species or stocks, their habitat, and their availability
for subsistence uses (where relevant). This analysis considers such
things as the nature of the potential adverse impact (such as
likelihood, scope, and range), the likelihood that the measure will be
effective if implemented, and the likelihood of successful
implementation; and
(2) The practicability of the measures for applicant
implementation. Practicability of implementation may consider such
things as cost, impact on activities, and, in the case of a military
readiness activity, specifically considers personnel safety,
practicality of implementation, and impact on the effectiveness of the
military readiness activity.
While the language of the least practicable adverse impact standard
calls for minimizing impacts to affected species or stocks, we
recognize that the reduction of impacts to those species or stocks
accrues through the application of mitigation measures that limit
impacts to individual animals. Accordingly, NMFS' analysis focuses on
measures that are designed to avoid or minimize impacts on individual
marine mammals that are likely to increase the probability or severity
of population-level effects.
While direct evidence of impacts to species or stocks from a
specified activity is rarely available, and additional study is still
needed to understand how specific disturbance events affect the fitness
of individuals of certain species, there have been improvements in
understanding the process by which disturbance effects are translated
to the population. With recent scientific advancements (both marine
mammal energetic research and the development of energetic frameworks),
the relative likelihood or degree of impacts on species or stocks may
often be inferred given a detailed understanding of the activity, the
environment, and the affected species or stocks--and the best available
science has been used here. This same information is used in the
development of mitigation measures and helps us understand how
mitigation measures contribute to lessening effects (or the risk
thereof) to species or stocks. We also acknowledge that there is always
the potential that new information, or a new recommendation could
become available in the future and necessitate reevaluation of
mitigation measures (which may be addressed through adaptive
management) to see if further reductions of population impacts are
possible and practicable.
In the evaluation of specific measures, the details of the
specified activity will necessarily inform each of the two primary
factors discussed above (expected reduction of impacts and
practicability), and are carefully considered to determine the types of
mitigation that are appropriate under the least practicable adverse
impact standard. Analysis of how a potential mitigation measure may
reduce adverse impacts on a marine mammal stock or species,
consideration of personnel safety, practicality of implementation, and
consideration of the impact on effectiveness of military readiness
activities are not issues that can be meaningfully evaluated through a
yes/no lens. The manner in which, and the degree to which,
implementation of a measure is expected to reduce impacts, as well as
its practicability in terms of these considerations, can vary widely.
For example, a time/area restriction could be of very high value for
decreasing population-level impacts (e.g., avoiding disturbance of
feeding females in an area of established biological importance) or it
could be of lower value (e.g., decreased disturbance in an area of high
productivity but of less biological importance). Regarding
practicability, a measure might involve restrictions in an area or time
that impede the Navy's ability to certify a strike group (higher impact
on mission effectiveness), or it could mean delaying a small in-port
training event by 30 minutes to avoid exposure of a marine mammal to
injurious levels of sound (lower impact). A responsible evaluation of
``least practicable adverse impact'' will consider the factors along
these realistic scales. Accordingly, the greater the likelihood that a
measure will contribute to reducing the probability or severity of
adverse impacts to the species or stock or its habitat, the greater the
weight that measure is given when considered in combination with
practicability to determine the appropriateness of the mitigation
measure, and vice versa. We discuss consideration of these factors in
greater detail below.
1. Reduction of adverse impacts to marine mammal species or stocks
and their habitat.\4\ The emphasis given to a measure's ability to
reduce the impacts on a species or stock considers the degree,
likelihood, and context of the anticipated reduction of impacts to
individuals (and how many individuals) as well as the status of the
species or stock.
---------------------------------------------------------------------------
\4\ We recognize the least practicable adverse impact standard
requires consideration of measures that will address minimizing
impacts on the availability of the species or stocks for subsistence
uses where relevant. Because subsistence uses are not implicated for
this action, we do not discuss them. However, a similar framework
would apply for evaluating those measures, taking into account the
MMPA's directive that we make a finding of no unmitigable adverse
impact on the availability of the species or stocks for taking for
subsistence, and the relevant implementing regulations.
---------------------------------------------------------------------------
The ultimate impact on any individual from a disturbance event
(which informs the likelihood of adverse species- or stock-level
effects) is dependent on the circumstances and associated contextual
factors, such as duration of exposure to stressors. Though any proposed
mitigation needs to be evaluated in the context of the specific
activity and the species or stocks affected, measures with the
following types of effects have greater value in reducing the
likelihood or severity of adverse species- or stock-level impacts:
Avoiding or minimizing injury or mortality; limiting interruption of
known feeding, breeding, mother/young, or resting behaviors; minimizing
the abandonment of important habitat (temporally and spatially);
minimizing the number of individuals subjected to these types of
disruptions; and limiting degradation of habitat. Mitigating these
types of effects is intended to reduce the likelihood that the activity
will result in energetic or other types of impacts that are more likely
to result in reduced reproductive success or survivorship. It is also
important to consider the degree of impacts that are expected in the
absence of mitigation in order to assess the added value of any
potential measures. Finally, because the least practicable adverse
impact standard gives NMFS discretion to weigh a variety of factors
when determining appropriate mitigation measures and because the focus
of the standard is on reducing impacts at the species or stock level,
the least practicable adverse impact standard does not compel
mitigation for every kind of take, or
[[Page 5852]]
every individual taken, if that mitigation is unlikely to meaningfully
contribute to the reduction of adverse impacts on the species or stock
and its habitat, even when practicable for implementation by the
applicant.
The status of the species or stock is also relevant in evaluating
the appropriateness of potential mitigation measures in the context of
least practicable adverse impact. The following are examples of factors
that may (either alone, or in combination) result in greater emphasis
on the importance of a mitigation measure in reducing impacts on a
species or stock: the stock is known to be decreasing or status is
unknown, but believed to be declining; the known annual mortality (from
any source) is approaching or exceeding the potential biological
removal (PBR) level (as defined in MMPA section 3(20)); the affected
species or stock is a small, resident population; or the stock is
involved in a UME or has other known vulnerabilities, such as
recovering from an oil spill.
Habitat mitigation, particularly as it relates to rookeries, mating
grounds, and areas of similar significance, is also relevant to
achieving the standard and can include measures such as reducing
impacts of the activity on known prey utilized in the activity area or
reducing impacts on physical habitat. As with species- or stock-related
mitigation, the emphasis given to a measure's ability to reduce impacts
on a species or stock's habitat considers the degree, likelihood, and
context of the anticipated reduction of impacts to habitat. Because
habitat value is informed by marine mammal presence and use, in some
cases there may be overlap in measures for the species or stock and for
use of habitat.
We consider available information indicating the likelihood of any
measure to accomplish its objective. If evidence shows that a measure
has not typically been effective nor successful, then either that
measure should be modified or the potential value of the measure to
reduce effects should be lowered.
2. Practicability. Factors considered may include cost, impact on
activities, and, in the case of a military readiness activity, will
include personnel safety, practicality of implementation, and impact on
the effectiveness of the military readiness activity (see MMPA section
101(a)(5)(A)(ii)).
Assessment of Mitigation Measures for the MITT Study Area
NMFS has fully reviewed the specified activities and the mitigation
measures included in the Navy's rulemaking/LOA application and the 2019
MITT DSEIS/OEIS to determine if the mitigation measures would result in
the least practicable adverse impact on marine mammals and their
habitat. NMFS worked with the Navy in the development of the Navy's
initially proposed measures, which are informed by years of
implementation and monitoring. A complete discussion of the Navy's
evaluation process used to develop, assess, and select mitigation
measures, which was informed by input from NMFS, can be found in
Chapter 5 (Mitigation) and Appendix I (Geographic Mitigation
Assessment) of the 2019 MITT DSEIS/OEIS. The process described in
Chapter 5 (Mitigation) and Appendix I (Geographic Mitigation
Assessment) of the 2019 MITT DSEIS/OEIS robustly supported NMFS'
independent evaluation of whether the mitigation measures would meet
the least practicable adverse impact standard. The Navy would be
required to implement the mitigation measures identified in this rule
for the full seven years to avoid or reduce potential impacts from
acoustic and explosive stressors.
As a general matter, where an applicant proposes measures that are
likely to reduce impacts to marine mammals, the fact that they are
included in the application indicates that the measures are
practicable, and it is not necessary for NMFS to conduct a detailed
analysis of the measures the applicant proposed (rather, they are
simply included). We note that in their application, the Navy added
three geographic mitigation measures that are new since the 2015-2020
MITT incidental take regulations: (1) Marpi Reef Geographic Mitigation
Area--to avoid potential impacts from explosives on marine mammals and
report hours of MFAS-MF1 within the mitigation area, which contains a
seasonal presence of humpback whales (2) Chalan Kanoa Reef Geographic
Mitigation Area--to avoid potential impacts from explosives on marine
mammals and report hours of MFAS-MF1 within the mitigation area, which
contains a seasonal presence of humpback whales and (3) Agat Bay
Nearshore Geographic Mitigation Area--to avoid potential impacts from
explosives and MFAS-MF1 on spinner dolphins. However, it is still
necessary for NMFS to consider whether there are additional practicable
measures that would meaningfully reduce the probability or severity of
impacts that could affect reproductive success or survivorship. In the
case of this rule, we worked with the Navy after it submitted its 2019
rulemaking/LOA application but prior to the development of this
proposed rule and the Navy also agreed to expand the geographic
mitigation areas for Marpi Reef and Chalan Kanoa Reef Geographic
Mitigation Areas to more fully encompass the 400 m isobaths based on
the available data indicating the presence of humpback whale mother/
calf pairs (seasonal breeding area), which is expected to further avoid
impacts from explosives that would be more likely to affect
reproduction or survival of individuals and could adversely impact the
species. The Navy also agreed to the addition of the Marpi Reef and
Chalan Kanoa Reef Awareness Notification Message Areas, which allow
Navy personnel to inform other personnel of the presence of humpback
whales, enabling them to avoid potential impacts from vessel strikes
and training and testing activities as these areas contain important
seasonal breeding habitat for this species.
Overall the Navy has agreed to procedural mitigation measures that
would reduce the probability and/or severity of impacts expected to
result from acute exposure to acoustic sources or explosives, ship
strike, and impacts to marine mammal habitat. Specifically, the Navy
would use a combination of delayed starts, powerdowns, and shutdowns to
avoid mortality or serious injury, minimize the likelihood or severity
of PTS or other injury, and reduce instances of TTS or more severe
behavioral disruption caused by acoustic sources or explosives. The
Navy would also implement multiple time/area restrictions that would
reduce take of marine mammals in areas or at times where they are known
to engage in important behaviors, such as calving, where the disruption
of those behaviors would have a higher probability of resulting in
impacts on reproduction or survival of individuals that could lead to
population-level impacts. Summaries of the Navy's procedural mitigation
measures and mitigation areas for the MITT Study Area are provided in
Tables 31 and 32.
[[Page 5853]]
Table 31--Summary of Procedural Mitigation
------------------------------------------------------------------------
Mitigation zone sizes and other
Stressor or activity requirements
------------------------------------------------------------------------
Environmental Awareness and Afloat Environmental Compliance Training
Education. program for applicable personnel.
Active Sonar................. Depending on sonar source: 1,000 yd power
down, 500 yd power down, and 200 yd shut
down.
Weapons Firing Noise......... 30 degrees on either side of the firing
line out to 70 yd.
Explosive Sonobuoys.......... 600 yd.
Explosive Torpedoes.......... 2,100 yd.
Explosive Medium-Caliber and 1,000 yd (large-caliber projectiles), 600
Large-Caliber Projectiles. yd. (medium-caliber projectiles during
surface-to-surface activities), or 200
yd. (medium-caliber projectiles during
air-to-surface activities).
Explosive Missiles and 2,000 yd (>21-500 lb net explosive
Rockets. weight), or 900 yd (0.6-20 lb net
explosive weight).
Explosive Bombs.............. 2,500 yd.
Sinking Exercises............ 2.5 NM.
Explosive Mine Countermeasure 600 yd.
and Neutralization
Activities.
Explosive Mine Neutralization 1,000 yd (charges using time delay
Activities involving Navy fuses), or 500 yd (positive control
Divers. charges).
Maritime Security Operations-- 200 yd.
Anti-Swimmer Grenades.
Vessel Movement.............. 500 yd (whales) or 200 yd (other marine
mammals).
Towed In-Water Devices....... 250 yd.
Small-, Medium-, and Large- 200 yd.
Caliber Non-Explosive
Practice Munitions.
Non-Explosive Missiles and 900 yd.
Rockets.
Non-Explosive Bombs and Mine 1,000 yd.
Shapes.
------------------------------------------------------------------------
Notes: lb: Pounds; NM: Nautical miles; yd: Yards
Table 32--Summary of Mitigation Areas for Marine Mammals
------------------------------------------------------------------------
Geographic mitigation area Approximate area
name (km\2\) Summary of actions
------------------------------------------------------------------------
Marpi Reef................... 33................. Humpback whales
(seasonally)
reporting MFAS-MF1;
no explosives year-
round.
Chalan Kanoa Reef............ 102................ Humpback whales
(seasonally)
reporting MFAS-MF1;
no explosives year-
round.
Agat Bay Nearshore........... 5.................. No MFAS- MF1 sonar
or explosive year-
round.
Marpi Reef and Chalan Kanoa 33 and 102......... Inform personnel to
Reef Notification Awareness the presence of
Message Areas. humpback whales
enabling them to
avoid potential
impacts from vessel
strikes and
training and
testing activities.
------------------------------------------------------------------------
The Navy assessed the practicability of the proposed measures in
the context of personnel safety, practicality of implementation, and
their impacts on the Navy's ability to meet their Title 10 requirements
and found that the measures are supportable. As described in more
detail below, NMFS has independently evaluated the measures the Navy
proposed in the manner described earlier in this section (i.e., in
consideration of their ability to reduce adverse impacts on marine
mammal species and their habitat and their practicability for
implementation). We have determined that the measures will
significantly and adequately reduce impacts on the affected marine
mammal species and their habitat and, further, be practicable for Navy
implementation. Therefore, the mitigation measures assure that Navy's
activities will have the least practicable adverse impact on the
species and their habitat.
The Navy also evaluated numerous measures in the 2019 MITT DSEIS/
OEIS that were not included in the Navy's rulemaking/LOA application,
and NMFS independently reviewed and preliminarily concurs with Navy's
analysis that their inclusion was not appropriate under the least
practicable adverse impact standard based on our assessment. The Navy
considered these additional potential mitigation measures in two
groups. First, Chapter 5 (Mitigation) of the 2019 MITT DSEIS/OEIS, in
the Measures Considered but Eliminated section, includes an analysis of
an array of different types of mitigation that have been recommended
over the years by non-governmental organizations or the public, through
scoping or public comment on environmental compliance documents.
Appendix I (Geographic Mitigation Assessment) of the 2019 MITT DSEIS/
OEIS includes an in-depth analysis of time/area restrictions that have
been recommended over time or previously implemented as a result of
litigation (outside of the MITT Study Area). As described in Chapter 5
(Mitigation) of the 2019 MITT DSEIS/OEIS, commenters sometimes
recommend that the Navy reduce its overall amount of training, reduce
explosive use, modify its sound sources, completely replace live
training with computer simulation, or include time of day restrictions.
Many of these mitigation measures could potentially reduce the number
of marine mammals taken, via direct reduction of the activities or
amount of sound energy put in the water. However, as described in
Chapter 5 (Mitigation) of the 2019 MITT DSEIS/OEIS, the Navy needs to
train and test in the conditions in which it fights--and these types of
modifications fundamentally change the activity in a manner that would
not support the purpose and need for the training and testing (i.e.,
are entirely impracticable) and therefore are not considered further.
NMFS finds the Navy's explanation for why adoption of these
recommendations would unacceptably undermine the purpose of the testing
and training persuasive. After independent review, NMFS finds Navy's
judgment on the impacts of potential mitigation measures to personnel
safety, practicality of implementation, and the effectiveness of
training and testing within the MITT Study Area persuasive, and for
these
[[Page 5854]]
reasons, NMFS finds that these measures do not meet the least
practicable adverse impact standard because they are not practicable.
Second, in Chapter 5 (Mitigation) of the 2019 MITT DSEIS/OEIS, the
Navy evaluated additional potential procedural mitigation measures,
including increased mitigation zones, ramp-up measures, additional
passive acoustic and visual monitoring, and decreased vessel speeds.
Some of these measures have the potential to incrementally reduce take
to some degree in certain circumstances, though the degree to which
this would occur is typically low or uncertain. However, as described
in the Navy's analysis, the measures would have significant direct
negative effects on mission effectiveness and are considered
impracticable (see Chapter 5 Mitigation of 2019 MITT DSEIS/OEIS). NMFS
independently reviewed the Navy's evaluation and concurs with this
assessment, which supports NMFS' preliminary findings that the
impracticability of this additional mitigation would greatly outweigh
any potential minor reduction in marine mammal impacts that might
result; therefore, these additional mitigation measures are not
warranted.
Last, Appendix I (Geographic Mitigation Assessment) of the 2019
MITT DSEIS/OEIS describes a comprehensive method for analyzing
potential geographic mitigation that includes consideration of both a
biological assessment of how the potential time/area limitation would
benefit the species and its habitat (e.g., is a key area of biological
importance or would result in avoidance or reduction of impacts) in the
context of the stressors of concern in the specific area and an
operational assessment of the practicability of implementation (e.g.,
including an assessment of the specific importance of that area for
training, considering proximity to training ranges and emergency
landing fields and other issues).
In its application, the Navy proposed several time/area mitigations
that were not included in the 2015-2020 MITT regulations. For most of
the areas that were considered in the 2019 MITT DSEIS/OEIS but not
included in this rule, the Navy found that the mitigation was not
warranted because the anticipated reduction of adverse impacts on
marine mammal species and their habitat was not sufficient to offset
the impracticability of implementation. In some cases potential
benefits to marine mammals were non-existent, while in others the
consequences on mission effectiveness were too great. NMFS has reviewed
the Navy's analysis in Chapter 5 Mitigation and Appendix I Geographic
Mitigation Assessment of the 2019 MITT DSEIS/OEIS, which considers the
same factors that NMFS considers to satisfy the least practicable
adverse impact standard, and concurs with the analysis and conclusions.
Therefore, NMFS is not proposing to include any of the measures that
the Navy ruled out in the 2019 MITT DSEIS/OEIS. Below are the
mitigation measures that NMFS determined will ensure the least
practicable adverse impact on all affected species and their habitat,
including the specific considerations for military readiness
activities. The following sections summarize the mitigation measures
that would be implemented in association with the training and testing
activities analyzed in this document. The mitigation measures are
organized into two categories: procedural mitigation and mitigation
areas.
Procedural Mitigation
Procedural mitigation is mitigation that the Navy would implement
whenever and wherever an applicable training or testing activity takes
place within the MITT Study Area. The Navy customizes procedural
mitigation for each applicable activity category or stressor.
Procedural mitigation generally involves: (1) The use of one or more
trained Lookouts to diligently observe for specific biological
resources (including marine mammals) within a mitigation zone, (2)
requirements for Lookouts to immediately communicate sightings of
specific biological resources to the appropriate watch station for
information dissemination, and (3) requirements for the watch station
to implement mitigation (e.g., halt an activity) until certain
recommencement conditions have been met. The first procedural
mitigation (Table 33) is designed to aid Lookouts and other applicable
Navy personnel with their observation, environmental compliance, and
reporting responsibilities. The remainder of the procedural mitigation
measures (Tables 34 through 50) are organized by stressor type and
activity category and includes acoustic stressors (i.e., active sonar,
weapons firing noise), explosive stressors (i.e., sonobuoys, torpedoes,
medium-caliber and large-caliber projectiles, missiles and rockets,
bombs, sinking exercises, mines, anti-swimmer grenades), and physical
disturbance and strike stressors (i.e., vessel movement, towed in-water
devices, small-, medium-, and large-caliber non-explosive practice
munitions, non-explosive missiles and rockets, non-explosive bombs and
mine shapes).
Table 33--Procedural Mitigation for Environmental Awareness and
Education
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
All training and testing activities, as applicable
Mitigation Requirements:
Appropriate Navy personnel (including civilian personnel) involved
in mitigation and training or testing activity reporting under the
specified activities will complete one or more modules of the U.S.
Navy Afloat Environmental Compliance Training Series, as identified
in their career path training plan. Modules include:
--Introduction to the U.S. Navy Afloat Environmental Compliance
Training Series. The introductory module provides information
on environmental laws (e.g., Endangered Species Act, Marine
Mammal Protection Act) and the corresponding responsibilities
that are relevant to Navy training and testing activities. The
material explains why environmental compliance is important in
supporting the Navy's commitment to environmental stewardship.
--Marine Species Awareness Training. All bridge watch personnel,
Commanding Officers, Executive Officers, maritime patrol
aircraft aircrews, anti-submarine warfare and mine warfare
rotary-wing aircrews, Lookouts, and equivalent civilian
personnel must successfully complete the Marine Species
Awareness Training prior to standing watch or serving as a
Lookout. The Marine Species Awareness Training provides
information on sighting cues, visual observation tools and
techniques, and sighting notification procedures. Navy
biologists developed Marine Species Awareness Training to
improve the effectiveness of visual observations for biological
resources, focusing on marine mammals and sea turtles, and
including floating vegetation, jellyfish aggregations, and
flocks of seabirds.
--U.S. Navy Protective Measures Assessment Protocol. This module
provides the necessary instruction for accessing mitigation
requirements during the event planning phase using the
Protective Measures Assessment Protocol software tool.
[[Page 5855]]
--U.S. Navy Sonar Positional Reporting System and Marine Mammal
Incident Reporting. This module provides instruction on the
procedures and activity reporting requirements for the Sonar
Positional Reporting System and marine mammal incident
reporting.
------------------------------------------------------------------------
Procedural Mitigation for Acoustic Stressors
Mitigation measures for acoustic stressors are provided in Tables
34 and 35.
Procedural Mitigation for Active Sonar
Procedural mitigation for active sonar is described in Table 34
below.
Table 34--Procedural Mitigation for Active Sonar
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Low-frequency active sonar, mid-frequency active sonar,
high-frequency active sonar
--For vessel-based active sonar activities, mitigation applies
only to sources that are positively controlled and deployed
from manned surface vessels (e.g., sonar sources towed from
manned surface platforms).
--For aircraft-based active sonar activities, mitigation applies
only to sources that are positively controlled and deployed
from manned aircraft that do not operate at high altitudes
(e.g., rotary-wing aircraft). Mitigation does not apply to
active sonar sources deployed from unmanned aircraft or
aircraft operating at high altitudes (e.g., maritime patrol
aircraft).
Number of Lookouts and Observation Platform:
Hull-mounted sources:
--1 Lookout: Platforms with space or manning restrictions while
underway (at the forward part of a small boat or ship) and
platforms using active sonar while moored or at anchor
(including pierside).
--2 Lookouts: Platforms without space or manning restrictions
while underway (at the forward part of the ship).
Sources that are not hull-mounted:
--1 Lookout on the ship or aircraft conducting the activity.
Mitigation Requirements:
Mitigation zones:
--During the activity at 1,000 yd, Navy personnel must power
down 6dB, at 500 yd, Navy personnel must power down an
additional 4 dB (for a total of 10 dB), and at 200 yd Navy
personnel must shut down for low-frequency active sonar >=200
dB and hull-mounted mid-frequency active sonar.
--200 yd shut down for low-frequency active sonar <200 dB, mid-
frequency active sonar sources that are not hull-mounted, and
high-frequency active sonar.
Prior to the initial start of the activity (e.g., when
maneuvering on station):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of active
sonar transmission.
During the activity:
--Low-frequency active sonar at >=200 dB or more, and hull-
mounted mid-frequency active sonar: Navy personnel must observe
the mitigation zone for marine mammals; power down active sonar
transmission by 6 dB if marine mammals are observed within
1,000 yd of the sonar source; power down an additional 4 dB
(for a total of 10 dB total) within 500 yd; cease transmission
within 200 yd.
--Low-frequency active sonar <200 dB, mid-frequency active sonar
sources that are not hull-mounted, and high-frequency active
sonar: Navy personnel must observe the mitigation zone for
marine mammals; cease active sonar transmission if observed
within 200 yd of the sonar source.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
or powering up active sonar transmission) until one of the
following conditions has been met: (1) The animal is observed
exiting the mitigation zone; (2) the animal is thought to have
exited the mitigation zone based on a determination of its
course, speed, and movement relative to the sonar source; (3)
the mitigation zone has been clear from any additional
sightings for 10 min. for aircraft-deployed sonar sources or 30
min for vessel-deployed sonar sources; (4) for mobile
activities, the active sonar source has transited a distance
equal to double that of the mitigation zone size beyond the
location of the last sighting; or (5) for activities using hull-
mounted sonar, the ship concludes that dolphins are
deliberately closing in on the ship to ride the ship's bow
wave, and are therefore out of the main transmission axis of
the sonar (and there are no other marine mammal sightings
within the mitigation zone).
------------------------------------------------------------------------
[[Page 5856]]
Procedural Mitigation for Weapons Firing Noise
Procedural mitigation for weapons firing noise is described in
Table 35 below.
Table 35--Procedural Mitigation for Weapons Firing Noise
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Weapons firing noise associated with large-caliber gunnery
activities.
Number of Lookouts and Observation Platform:
1 Lookout positioned on the ship conducting the firing.
Depending on the activity, the Lookout could be the same as
the one described in Procedural Mitigation for Explosive Medium-
and Large-Caliber Projectiles (Table 38) or Procedural Mitigation
for Small-, Medium-, and Large-Caliber Non-Explosive Practice
Munitions (Table 47).
Mitigation Requirements:
Mitigation Zone:
--30[deg] on either side of the firing line out to 70 yd from
the muzzle of the weapon being fired.
Prior to the initial start of the activity:
--Observe the mitigation zone for marine mammals; if observed,
relocate or delay the start of weapons firing.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease weapons firing.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
weapons firing) until one of the following conditions has been
met: (1) The animal is observed exiting the mitigation zone;
(2) the animal is thought to have exited the mitigation zone
based on a determination of its course, speed, and movement
relative to the firing ship; (3) the mitigation zone has been
clear from any additional sightings for 30 min; or (4) for
mobile activities, the firing ship has transited a distance
equal to double that of the mitigation zone size beyond the
location of the last sighting.
------------------------------------------------------------------------
Procedural Mitigation for Explosive Stressors
Mitigation measures for explosive stressors are provided in Tables
36 through 44.
Procedural Mitigation for Explosive Sonobuoys
Procedural mitigation for explosive sonobuoys is described in Table
36 below.
Table 36--Procedural Mitigation for Explosive Sonobuoys
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Explosive sonobuoys.
Number of Lookouts and Observation Platform:
1 Lookout positioned in an aircraft or on a small boat.
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation Zone:
--600 yd around an explosive sonobuoy.
Prior to the initial start of the activity (e.g., during
deployment of a sonobuoy pattern, which typically lasts 20-30
minutes):
--Conduct passive acoustic monitoring for marine mammals; use
information from detections to assist visual observations.
--Visually observe the mitigation zone for marine mammals; if
marine mammals are observed, relocate or delay the start of
sonobuoy or source/receiver pair detonations.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease sonobuoy or source/receiver pair
detonations.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
detonations) until one of the following conditions has been
met: (1) The animal is observed exiting the mitigation zone;
(2) the animal is thought to have exited the mitigation zone
based on a determination of its course, speed, and movement
relative to the sonobuoy; or (3) the mitigation zone has been
clear from any additional sightings for 10 min when the
activity involves aircraft that have fuel constraints, or 30
min when the activity involves aircraft that are not typically
fuel constrained.
After completion of the activity (e.g., prior to
maneuvering off station):
--When practical (e.g., when platforms are not constrained by
fuel restrictions or mission-essential follow-on commitments),
observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
[[Page 5857]]
Procedural Mitigation for Explosive Torpedoes
Procedural mitigation for explosive torpedoes is described in Table
37 below.
Table 37--Procedural Mitigation for Explosive Torpedoes
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Explosive Torpedoes.
Number of Lookouts and Observation Platform:
1 Lookout positioned in an aircraft.
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation Zone:
--2,100 yd around the intended impact location.
Prior to the start of the activity (e.g., during deployment
of the target):
--Conduct passive acoustic monitoring for marine mammals; use
information from detections to assist visual observations.
--Visually observe the mitigation zone for marine mammals; if
marine mammals are observed, relocate or delay the start of
firing.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease firing.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
firing) until one of the following conditions has been met: (1)
The animal is observed exiting the mitigation zone; (2) the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to
the intended impact location; or (3) the mitigation zone has
been clear from any additional sightings for 10 min when the
activity involves aircraft that have fuel constraints, or 30
min when the activity involves aircraft that are not typically
fuel constrained.
After completion of the activity (e.g., prior to
maneuvering off station):
--When practical (e.g., when platforms are not constrained by
fuel restrictions or mission-essential follow-on commitments),
observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
Procedural Mitigation for Medium- and Large-Caliber Projectiles
Procedural mitigation for medium- and large-caliber projectiles is
described in Table 38 below.
Table 38--Procedural Mitigation for Explosive Medium-Caliber and Large-
Caliber Projectiles
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Gunnery activities using explosive medium-caliber and large-
caliber projectiles.
--Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
1 Lookout on the vessel or aircraft conducting the
activity.
--For activities using explosive large-caliber projectiles,
depending on the activity, the Lookout could be the same as the
one described in Weapons Firing Noise (Table 35).
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation zones:
--200 yd around the intended impact location for air-to-surface
activities using explosive medium-caliber projectiles.
--600 yd around the intended impact location for surface-to-
surface activities using explosive medium-caliber projectiles.
--1,000 yd around the intended impact location for surface-to-
surface activities using explosive large-caliber projectiles.
Prior to the initial start of the activity (e.g., when
maneuvering on station):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of firing.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease firing.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
[[Page 5858]]
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
firing) until one of the following conditions has been met: (1)
The animal is observed exiting the mitigation zone; (2) the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to
the intended impact location; (3) the mitigation zone has been
clear from any additional sightings for 10 min for aircraft-
based firing or 30 min for vessel-based firing; or (4) for
activities using mobile targets, the intended impact location
has transited a distance equal to double that of the mitigation
zone size beyond the location of the last sighting.
After completion of the activity (e.g., prior to
maneuvering off station):
--When practical (e.g., when platforms are not constrained by
fuel restrictions or mission-essential follow-on commitments),
observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
Procedural Mitigation for Explosive Missiles and Rockets
Procedural mitigation for explosive missiles and rockets is
described in Table 39 below.
Table 39--Procedural Mitigation for Explosive Missiles and Rockets
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Aircraft-deployed explosive missiles and rockets.
--Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
1 Lookout positioned in an aircraft.
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation zones:
--900 yd around the intended impact location for missiles or
rockets with 0.6-20 lb net explosive weight.
--2,000 yd around the intended impact location for missiles with
21-500 lb net explosive weight.
Prior to the initial start of the activity (e.g., during a
fly-over of the mitigation zone):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of firing.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease firing.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
firing) until one of the following conditions has been met: (1)
The animal is observed exiting the mitigation zone; (2) the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to
the intended impact location; or (3) the mitigation zone has
been clear from any additional sightings for 10 min when the
activity involves aircraft that have fuel constraints, or 30
min when the activity involves aircraft that are not typically
fuel constrained.
After completion of the activity (e.g., prior to
maneuvering off station):
--When practical (e.g., when platforms are not constrained by
fuel restrictions or mission-essential follow-on commitments),
observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
Procedural Mitigation for Explosive Bombs
Procedural mitigation for explosive bombs is described in Table 40
below.
Table 40--Procedural Mitigation for Explosive Bombs
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Explosive bombs.
Number of Lookouts and Observation Platform:
1 Lookout positioned in the aircraft conducting the
activity.
[[Page 5859]]
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation zone:
--2,500 yd around the intended target.
Prior to the initial start of the activity (e.g., when
arriving on station):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of bomb
deployment.
During the activity (e.g., during target approach):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease bomb deployment.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
bomb deployment) until one of the following conditions has been
met: (1) The animal is observed exiting the mitigation zone;
(2) the animal is thought to have exited the mitigation zone
based on a determination of its course, speed, and movement
relative to the intended target; (3) the mitigation zone has
been clear from any additional sightings for 10 min; or (4) for
activities using mobile targets, the intended target has
transited a distance equal to double that of the mitigation
zone size beyond the location of the last sighting.
After completion of the activity (e.g., prior to
maneuvering off station):
--When practical (e.g., when platforms are not constrained by
fuel restrictions or mission-essential follow-on commitments),
observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
Procedural Mitigation for Sinking Exercises
Procedural mitigation for sinking exercises is described in Table
41 below.
Table 41--Procedural Mitigation for Sinking Exercises
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Sinking exercises.
Number of Lookouts and Observation Platform:
2 Lookouts (one positioned in an aircraft and one on a
vessel).
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation Zone:
--2.5 NM around the target ship hulk.
Prior to the initial start of the activity (90 min. prior
to the first firing):
--Conduct aerial observations of the mitigation zone for marine
mammals; if marine mammals are observed, delay the start of
firing.
During the activity:
--Conduct passive acoustic monitoring for marine mammals; use
information from detections to assist visual observations.
--Visually observe the mitigation zone for marine mammals from
the vessel; if marine mammals are observed, Navy personnel must
cease firing.
--Immediately after any planned or unplanned breaks in weapons
firing of longer than 2 hours, observe the mitigation zone for
marine mammals from the aircraft and vessel; if marine mammals
are observed, Navy personnel must delay recommencement of
firing.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
firing) until one of the following conditions has been met: (1)
The animal is observed exiting the mitigation zone; (2) the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to
the target ship hulk; or (3) the mitigation zone has been clear
from any additional sightings for 30 min.
After completion of the activity (for 2 hours after sinking
the vessel or until sunset, whichever comes first):
--Observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, Navy personnel
must follow established incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
[[Page 5860]]
Procedural Mitigation for Explosive Mine Countermeasure and
Neutralization Activities
Procedural mitigation for explosive mine countermeasure and
neutralization activities is described in Table 42 below.
Table 42--Procedural Mitigation for Explosive Mine Countermeasure and
Neutralization Activities
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Explosive mine countermeasure and neutralization
activities.
Number of Lookouts and Observation Platform:
1 Lookout positioned on a vessel or in an aircraft.
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation Zone:
--600 yd around the detonation site.
Prior to the initial start of the activity (e.g., when
maneuvering on station; typically, 10 min when the activity
involves aircraft that have fuel constraints, or 30 min when the
activity involves aircraft that are not typically fuel
constrained):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of
detonations.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease detonations.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
detonations) until one of the following conditions has been
met: (1) The animal is observed exiting the mitigation zone;
(2) the animal is thought to have exited the mitigation zone
based on a determination of its course, speed, and movement
relative to detonation site; or (3) the mitigation zone has
been clear from any additional sightings for 10 min when the
activity involves aircraft that have fuel constraints, or 30
min. when the activity involves aircraft that are not typically
fuel constrained.
After completion of the activity (typically 10 min when the
activity involves aircraft that have fuel constraints, or 30 min
when the activity involves aircraft that are not typically fuel
constrained):
--Observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
Procedural Mitigation for Explosive Mine Neutralization Activities
Involving Navy Divers
Procedural mitigation for explosive mine neutralization activities
involving Navy divers is described in Table 43 below.
Table 43--Procedural Mitigation for Explosive Mine Neutralization
Activities Involving Navy Divers
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Explosive mine neutralization activities involving Navy
divers.
Number of Lookouts and Observation Platforms:
2 Lookouts (two small boats with one Lookout each, or one
Lookout on a small boat and one in a rotary-wing aircraft) when
implementing the smaller mitigation zone.
4 Lookouts (two small boats with two Lookouts each), and a
pilot or member of an aircrew will serve as an additional Lookout
if aircraft are used during the activity, when implementing the
larger mitigation zone.
All divers placing the charges on mines will support the
Lookouts while performing their regular duties and will report
applicable sightings to their supporting small boat or Range Safety
Officer.
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation Zones:
--500 yd around the detonation site during activities under
positive control.
--1,000 yd around the detonation site during activities using
time-delay fuses.
Prior to the initial start of the activity (e.g., when
maneuvering on station for activities under positive control; 30
min for activities using time-delay firing devices):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of
detonations or fuse initiation.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease detonations or fuse initiation.
[[Page 5861]]
--To the maximum extent practical depending on mission
requirements, safety, and environmental conditions, boats will
position themselves near the mid-point of the mitigation zone
radius (but outside of the detonation plume and human safety
zone), will position themselves on opposite sides of the
detonation location (when two boats are used), and will travel
in a circular pattern around the detonation location with one
Lookout observing inward toward the detonation site and the
other observing outward toward the perimeter of the mitigation
zone.
--If used, aircraft will travel in a circular pattern around the
detonation location to the maximum extent practicable.
--The Navy will not set time-delay firing devices to exceed 10
min.
Commencement/recommencement conditions after a marine
mammal before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
detonations) until one of the following conditions has been
met: (1) The animal is observed exiting the mitigation zone;
(2) the animal is thought to have exited the mitigation zone
based on a determination of its course, speed, and movement
relative to the detonation site; or (3) the mitigation zone has
been clear from any additional sightings for 10 min during
activities under positive control with aircraft that have fuel
constraints, or 30 min during activities under positive control
with aircraft that are not typically fuel constrained and
during activities using time-delay firing devices.
After completion of an activity (for 30 min):
--Observe the vicinity of where detonations occurred; if any
injured or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
Procedural Mitigation for Maritime Security Operations--Anti-Swimmer
Grenades
Procedural mitigation for maritime security operations--anti-
swimmer grenades is described in Table 44 below.
Table 44--Procedural Mitigation for Maritime Security Operations--Anti-
Swimmer Grenades
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Maritime Security Operations--Anti-Swimmer Grenades.
Number of Lookouts and Observation Platform:
1 Lookout positioned on the small boat conducting the
activity.
If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) will support observing the mitigation zone for
applicable biological resources while performing their regular
duties.
Mitigation Requirements:
Mitigation zone:
--200 yd around the intended detonation location.
Prior to the initial start of the activity (e.g., when
maneuvering on station):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of
detonations.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease detonations.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
detonations) until one of the following conditions has been
met: (1) The animal is observed exiting the mitigation zone;
(2) the animal is thought to have exited the mitigation zone
based on a determination of its course, speed, and movement
relative to the intended detonation location; (3) the
mitigation zone has been clear from any additional sightings
for 30 min; or (4) the intended detonation location has
transited a distance equal to double that of the mitigation
zone size beyond the location of the last sighting.
After completion of the activity (e.g., prior to
maneuvering off station):
--When practical (e.g., when platforms are not constrained by
fuel restrictions or mission-essential follow-on commitments),
observe vicinity of where detonations occurred; if any injured
or dead marine mammals are observed, follow established
incident reporting procedures.
--If additional platforms are supporting this activity (e.g.,
providing range clearance), these assets will assist in the
visual observation of the area where detonations occurred.
------------------------------------------------------------------------
Procedural Mitigation for Physical Disturbance and Strike Stressors
Mitigation measures for physical disturbance and strike stressors
are provided in Table 45 through Table 49.
Procedural Mitigation for Vessel Movement
Procedural mitigation for vessel movement is described in Table 45
below.
[[Page 5862]]
Table 45--Procedural Mitigation for Vessel Movement
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Vessel movement:
--The mitigation will not be applied if (1) the vessel's safety
is threatened, (2) the vessel is restricted in its ability to
maneuver (e.g., during launching and recovery of aircraft or
landing craft, during towing activities, when mooring, etc.),
(3) the vessel is operated autonomously, or (4) when
impractical based on mission requirements (e.g., during
Amphibious Assault and Amphibious Raid exercises).
Number of Lookouts and Observation Platform:
1 Lookout on the vessel that is underway.
Mitigation Requirements:
Mitigation Zones:
--500 yd around whales.
--200 yd around other marine mammals (except bow-riding
dolphins).
During the activity:
--When underway, observe the mitigation zone for marine mammals;
if marine mammals are observed, maneuver to maintain distance.
Additional requirements:
--If a marine mammal vessel strike occurs, the Navy will follow
the established incident reporting procedures.
------------------------------------------------------------------------
Procedural Mitigation for Towed In-Water Devices
Procedural mitigation for towed in-water devices is described in
Table 46 below.
Table 46--Procedural Mitigation for Towed In-Water Devices
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Towed in-water devices:
--Mitigation applies to devices that are towed from a manned
surface platform or manned aircraft.
--The mitigation will not be applied if the safety of the towing
platform or in-water device is threatened.
Number of Lookouts and Observation Platform:
1 Lookout positioned on a manned towing platform.
Mitigation Requirements:
Mitigation Zones:
--250 yd. around marine mammals.
During the activity (i.e., when towing an in-water device):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, maneuver to maintain distance.
------------------------------------------------------------------------
Procedural Mitigation for Small-, Medium-, and Large-Caliber Non-
Explosive Practice Munitions
Procedural mitigation for small-, medium-, and large-caliber non-
explosive practice munitions is described in Table 47 below.
Table 47--Procedural Mitigation for Small-, Medium-, and Large-Caliber
Non-Explosive Practice Munitions
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Gunnery activities using small-, medium-, and large-caliber
non-explosive practice munitions
--Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
1 Lookout positioned on the platform conducting the
activity.
Depending on the activity, the Lookout could be the same as
the one described in Procedural Mitigation for Weapons Firing Noise
(Table 35).
Mitigation Requirements:
Mitigation Zone:
--200 yd around the intended impact location.
Prior to the initial start of the activity (e.g., when
maneuvering on station):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of firing.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease firing.
Commencement/recommencement conditions after a marine
mammal sighting before or during the activity:
[[Page 5863]]
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
firing) until one of the following conditions has been met: (1)
The animal is observed exiting the mitigation zone; (2) the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to
the intended impact location; (3) the mitigation zone has been
clear from any additional sightings for 10 min for aircraft-
based firing or 30 min for vessel-based firing; or (4) for
activities using a mobile target, the intended impact location
has transited a distance equal to double that of the mitigation
zone size beyond the location of the last sighting.
------------------------------------------------------------------------
Procedural Mitigation for Non-Explosive Missiles and Rockets
Procedural mitigation for non-explosive missiles and rockets is
described in Table 48 below.
Table 48--Procedural Mitigation for Non-Explosive Missiles and Rockets
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Aircraft-deployed non-explosive missiles and rockets.
Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
1 Lookout positioned in an aircraft.
Mitigation Requirements:
Mitigation Zone:
--900 yd. around the intended impact location.
Prior to the initial start of the activity (e.g., during a
fly-over of the mitigation zone):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay the start of firing.
During the activity:
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease firing.
Commencement/recommencement conditions after a marine
mammal sighting prior to or during the activity:
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
firing) until one of the following conditions has been met: (1)
The animal is observed exiting the mitigation zone; (2) the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to
the intended impact location; or (3) the mitigation zone has
been clear from any additional sightings for 10 min when the
activity involves aircraft that have fuel constraints, or 30
min when the activity involves aircraft that are not typically
fuel constrained.
------------------------------------------------------------------------
Procedural Mitigation for Non-Explosive Bombs and Mine Shapes
Procedural mitigation for non-explosive bombs and mine shapes is
described in Table 49 below.
Table 49--Procedural Mitigation for Non-Explosive Bombs and Mine Shapes
------------------------------------------------------------------------
Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
Non-explosive bombs.
Non-explosive mine shapes during mine laying activities.
Number of Lookouts and Observation Platform:
1 Lookout positioned in an aircraft.
Mitigation Requirements:
Mitigation Zone:
--1,000 yd around the intended target.
Prior to the start of the activity (e.g., when arriving on
station):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, relocate or delay start of bomb
deployment or mine laying.
During the activity (e.g., during approach of the target or
intended minefield location):
--Observe the mitigation zone for marine mammals; if marine
mammals are observed, cease bomb deployment or mine laying.
Commencement/recommencement conditions after a marine
mammal sighting prior to or during the activity:
[[Page 5864]]
--Navy personnel will allow a sighted marine mammal to leave the
mitigation zone prior to the initial start of the activity (by
delaying the start) or during the activity (by not recommencing
bomb deployment or mine laying) until one of the following
conditions has been met: (1) The animal is observed exiting the
mitigation zone; (2) the animal is thought to have exited the
mitigation zone based on a determination of its course, speed,
and movement relative to the intended target or minefield
location; (3) the mitigation zone has been clear from any
additional sightings for 10 min; or (4) for activities using
mobile targets, the intended target has transited a distance
equal to double that of the mitigation zone size beyond the
location of the last sighting.
------------------------------------------------------------------------
Mitigation Areas
In addition to procedural mitigation, the Navy would implement
mitigation measures within mitigation areas to avoid or minimize
potential impacts on marine mammals. A full technical analysis (for
which the methods were summarized above) of the mitigation areas that
the Navy considered for marine mammals is provided in Appendix I
(Geographic Mitigation Assessment) of the 2019 MITT DSEIS/OEIS. The
Navy took into account public comments received on the 2019 MITT DSEIS/
OEIS, best available science, and the practicability of implementing
additional mitigation measures and has enhanced its mitigation areas
and mitigation measures, beyond the 2015-2020 regulations, to further
reduce impacts to marine mammals.
NMFS also worked with the Navy after it submitted its 2019
rulemaking/LOA application but prior to the development of this
proposed rule and the Navy also agreed to expand the geographic
mitigation areas for Marpi Reef and Chalan Kanoa Reef Geographic
Mitigation Areas to more fully encompass the 400 m isobaths based on
the available data indicating the presence of humpback whale mother/
calf pairs (seasonal breeding area), which is expected to further avoid
impacts from explosives that would be more likely to affect
reproduction or survival of individuals and could adversely impact the
species. The Navy also agreed to the addition of the Marpi Reef and
Chalan Kanoa Reef Awareness Notification Message Areas, which allow
Navy personnel to inform other personnel of the presence of humpback
whales, enabling them to avoid potential impacts from vessel strikes
and training and testing activities as these areas contain important
seasonal breeding habitat for this species.
Information on the mitigation measures that the Navy will implement
within geographic mitigation areas is provided in Table 50 (see below).
The mitigation applies year-round unless specified otherwise in the
table.
NMFS conducted an independent analysis of the mitigation areas that
the Navy proposed, which are described below. NMFS preliminarily
concurs with the Navy's analysis, which indicates that the measures in
these mitigation areas are both practicable and will reduce the
likelihood or severity of adverse impacts to marine mammal species or
their habitat in the manner described in the Navy's analysis and this
rule. NMFS is heavily reliant on the Navy's description of operational
practicability, since the Navy is best equipped to describe the degree
to which a given mitigation measure affects personnel safety or mission
effectiveness, and is practical to implement. The Navy considers the
measures in this proposed rule to be practicable, and NMFS concurs. We
further discuss the manner in which the Geographic Mitigation Areas in
the proposed rule will reduce the likelihood or severity of adverse
impacts to marine mammal species or their habitat in the Preliminary
Analysis and Negligible Impact Determination section. Marpi Reef and
Chalan Kanoa Reef Geographic Mitigation Areas (Both seasonal and year
round):
The Navy would not use in-water explosives year-round. The Navy
would also report the total hours of MF1 surface ship hull-mounted mid-
frequency active sonar from December through April used in this area in
its annual training and testing activity reports submitted to NMFS
(Table 50).
Marpi Reef and Chalan Kanoa Reef Awareness Notification Message
Areas (December-April):
The Navy would issue an annual seasonal awareness notification
message to alert ships and aircraft operating in the area to the
possible presence of large whales or increased concentrations of
humpback whales between December and April. To maintain safety of
navigation and to avoid interactions with large whales during transits,
the Navy would instruct vessels to remain vigilant to the presence of
large whales, that when concentrated seasonally, may become vulnerable
to vessel strikes. Platforms would use the information from the
awareness notification messages to assist their visual observation of
applicable mitigation zones during training and testing activities and
to aid in the implementation of procedural mitigation (Table 50).
Agat Bay Nearshore Geographic Mitigation Area:
The Navy would not use in-water explosives year-round. The Navy
also would not use MF1 ship hull-mounted mid-frequency active sonar
year round (Table 50).
Table 50--Geographic Mitigation Areas for Marine Mammals in the MITT
Study Area
------------------------------------------------------------------------
Geographic Mitigation Area Description
-------------------------------------------------------------------------
Stressor or Activity:
MF1 Sonar.
Explosives.
Mitigation Area Requirements:
Marpi Reef:
--Seasonal (December-April): The Navy will report the total
hours of MF1 surface ship hull-mounted mid-frequency active
sonar used in this area in its annual training and testing
activity reports submitted to NMFS.
[[Page 5865]]
--Year-round: Year-round prohibition on in-water explosives.
Should national security present a requirement to use
explosives that could potentially result in the take of marine
mammals during training or testing, naval units will obtain
permission from the appropriate designated Command authority
prior to commencement of the activity. The Navy will provide
NMFS with advance notification and include the information
(e.g., explosives usage) in its annual activity reports
submitted to NMFS.
Chalan Kanoa Reef:
--Seasonal (December-April): The Navy will report the total
hours of MF1 surface ship hull-mounted mid-frequency active
sonar used in this area in its annual training and testing
activity reports submitted to NMFS.
--Year-round: Year-round prohibition on in-water explosives.
Should national security present a requirement to use
explosives that could potentially result in the take of marine
mammals during training or testing, naval units will obtain
permission from the appropriate designated Command authority
prior to commencement of the activity. The Navy will provide
NMFS with advance notification and include the information
(e.g., explosives usage) in its annual activity reports
submitted to NMFS.
Marpi Reef and Chalan Kanoa Reef Awareness Notification
Message Areas:
--Seasonal (December-April): The Navy will issue an annual
seasonal awareness notification message to alert ships and
aircraft operating in the area to the possible presence of
large whales or increased concentrations of humpback whales
between December and April. To maintain safety of navigation
and to avoid interactions with large whales during transits,
the Navy will instruct vessels to remain vigilant to the
presence of large whales, that when concentrated seasonally,
may become vulnerable to vessel strikes. Platforms will use the
information from the awareness notification messages to assist
their visual observation of applicable mitigation zones during
training and testing activities and to aid in the
implementation of procedural mitigation.
Agat Bay Nearshore:
--Year-round prohibition on use of MF1 ship hull-mounted mid-
frequency active sonar and in-water explosives. Should national
security present a requirement to use surface ship hull-mounted
active sonar or explosives that could potentially result in the
take of marine mammals during training or testing, naval units
will obtain permission from the appropriate designated Command
authority prior to commencement of the activity. The Navy will
provide NMFS with advance notification and include the
information (e.g., sonar hours or explosives usage) in its
annual activity reports submitted to NMFS.
------------------------------------------------------------------------
Humpback whales have been sighted in the MITT Study Area from
January through March (U.S. Department of the Navy, 2005b; Uyeyama,
2014), and male humpback songs have been recorded from December through
April (Hill et al., 2017a; Klinck et al., 2016; Munger et al., 2014;
Norris et al., 2014; Oleson et al., 2015). Recent scientific research
by NOAA Fisheries Pacific Island Fisheries Science Center (PIFSC)
indicates the shallower water around Marpi Reef and Chalan Kanoa Reef
are important habitat for humpback whale breeding and calving. With the
presence of humpback whale newborn calves and competitive groups,
researchers were able to confirm this new breeding location (NOAA,
2018). The Navy obtained all humpback whale sighting data in the
Marianas from the PIFSC (2015-2019) to determine the extent of this
geographic mitigation area. Humpback whales, including mother-calf
pairs, have been seasonally present in the Marpi Reef Area in shallow
waters (out to the 400 m isobaths) and the area may be of biological
importance to humpback whales for biologically important life processes
associated with reproduction (e.g., breeding, birthing, and nursing)
for part of the year.
Calves are considered more sensitive and susceptible to adverse
impacts from Navy stressors than adults (especially given their lesser
weight and the association between weight and explosive impacts), as
well as being especially reliant upon mother-calf communication for
protection and guidance. Both gestation and lactation increase energy
demands for mothers. Breeding activities typically involve
vocalizations and complex social interactions that can include violent
interactions between males. Reducing exposure of humpback whales to
explosive detonations in this area and time is expected to reduce the
likelihood of impacts that could affect reproduction or survival, by
minimizing impacts on calves during this sensitive life stage, avoiding
the additional energetic costs to mothers of avoiding the area during
explosive exercises, and minimizing the chances that important breeding
behaviors are interrupted to the point that reproduction is inhibited
or abandoned for the year, or otherwise interfered with. Since the Navy
submitted its application, it has extended both the Marpi Reef and
Chalan Kanoa Reef Mitigation Areas out to the 400 m isobath to account
for animals transiting to and from the more critical < 200 m areas used
by humpback whales for breeding behaviors (Figures 2 and 3 below).
Additional data would be needed to determine which DPS the humpbacks
are assigned to.
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[[Page 5866]]
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[[Page 5867]]
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Agat Bay Nearshore Geographic Mitigation Area (year-round):
The Navy would not use MF1 ship hull-mounted mid-frequency active
sonar and in-water explosives year-round in the Agat Bay Nearshore
Geographic Mitigation Area (Table 50 above). Spinner dolphins are known
to
[[Page 5868]]
congregate and rest in Agat Bay. Behavioral disruptions during resting
periods can adversely impact health and energetic budgets by not
allowing animals to get the needed rest and/or by creating the need to
travel and expend additional energy to find other suitable resting
areas. Avoiding sonar and explosives in this area reduces the
likelihood of impacts that would affect reproduction and survival.
The boundaries of the proposed Agat Bay Nearshore Geographic
Mitigation Area were defined by Navy scientists based on spinner
dolphin sightings documented during small boat surveys from 2010
through 2014. Spinner dolphins have been the most frequently
encountered species during small boat reconnaissance surveys conducted
in the Mariana Islands since 2010. Consistent with more intensive
studies completed for the species in the Hawaiian Islands, island-
associated spinner dolphins are expected to occur in shallow water
resting areas (about 50 meters (m) deep or less) in the morning and
throughout the middle of the day, moving into deep waters offshore
during the night to feed (Heenehan et al., 2016b; Heenehan et al.,
2017a; Hill et al., 2010; Norris & Dohl, 1980).
The Agat Bay Nearshore Geographic Mitigation Area encompasses the
shoreline between Tipalao, Dadi Beach, and Agat on the west coast of
Guam, with a boundary across the bay enclosing an area of approximately
5 km\2\ in relatively shallow waters (less than 100 m) (Figure 4).
[[Page 5869]]
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Marpi Reef and Chalan Kanoa Reef Awareness Notification Message
Areas (Seasonal):
The Navy would issue an annual seasonal awareness notification
message to alert ships and aircraft operating in the area to the
possible presence of large whales including increased concentrations of
humpback whales between December and April. To maintain safety of
navigation and to avoid interactions with large whales during transits,
the Navy would instruct vessels to remain vigilant to the presence of
large whales, that when concentrated seasonally, may become more
vulnerable to vessel strikes. Platforms would use the information from
the awareness notification messages to assist their visual observation
of applicable mitigation
[[Page 5870]]
zones during training and testing activities and to aid in the
implementation of procedural mitigation. This restriction would further
reduce any potential for vessel strike of humpback whales when they may
be seasonally concentrated.
Mitigation Conclusions
NMFS has carefully evaluated the Navy's proposed mitigation
measures--many of which were developed with NMFS' input during the
previous phases of Navy training and testing authorizations--and
considered a broad range of other measures (i.e., the measures
considered but eliminated in the 2019 MITT DSEIS/OEIS, which reflect
many of the comments that have arisen via NMFS or public input in past
years) in the context of ensuring that NMFS prescribes the means of
effecting the least practicable adverse impact on the affected marine
mammal species and their habitat. Our evaluation of potential measures
included consideration of the following factors in relation to one
another: The manner in which, and the degree to which, the successful
implementation of the mitigation measures is expected to reduce the
likelihood and/or magnitude of adverse impacts to marine mammal species
and their habitat; the proven or likely efficacy of the measures; and
the practicability of the measures for applicant implementation,
including consideration of personnel safety, practicality of
implementation, and impact on the effectiveness of the military
readiness activity.
Based on our evaluation of the Navy's proposed measures, as well as
other measures considered by the Navy and NMFS, NMFS has preliminarily
determined that these proposed mitigation measures are appropriate
means of effecting the least practicable adverse impact on marine
mammal species and their habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and
considering specifically personnel safety, practicality of
implementation, and impact on the effectiveness of the military
readiness activity. Additionally, an adaptive management component
helps further ensure that mitigation is regularly assessed and provides
a mechanism to improve the mitigation, based on the factors above,
through modification as appropriate.
The proposed rule comment period provides the public an opportunity
to submit recommendations, views, and/or concerns regarding the Navy's
activities and the proposed mitigation measures. While NMFS has
preliminarily determined that the Navy's proposed mitigation measures
would effect the least practicable adverse impact on the affected
species and their habitat, NMFS will consider all public comments to
help inform our final determination. Consequently, the proposed
mitigation measures may be refined, modified, removed, or added to
prior to the issuance of the final rule based on public comments
received and, as appropriate, analysis of additional potential
mitigation measures.
Proposed Monitoring
Section 101(a)(5)(A) of the MMPA states that in order to authorize
incidental take for an activity, NMFS must set forth requirements
pertaining to the monitoring and reporting of such taking. The MMPA
implementing regulations at 50 CFR 216.104(a)(13) indicate that
requests for incidental take authorizations must include the suggested
means of accomplishing the necessary monitoring and reporting that will
result in increased knowledge of the species and of the level of taking
or impacts on populations of marine mammals that are expected to be
present.
Although the Navy has been conducting research and monitoring in
the MITT Study Area for over 20 years, it developed a formal marine
species monitoring program in support of the MMPA and ESA
authorizations in 2009. This robust program has resulted in hundreds of
technical reports and publications on marine mammals that have informed
Navy and NMFS analyses in environmental planning documents, rules, and
Biological Opinions. The reports are made available to the public on
the Navy's marine species monitoring website
(www.navymarinespeciesmonitoring.us) and the data on the Ocean
Biogeographic Information System Spatial Ecological Analysis of
Megavertebrate Populations (OBIS-SEAMAP) (http://seamap.env.duke.edu/).
The Navy will continue collecting monitoring data to inform our
understanding of the occurrence of marine mammals in the MITT Study
Area; the likely exposure of marine mammals to stressors of concern in
the MITT Study Area; the response of marine mammals to exposures to
stressors; the consequences of a particular marine mammal response to
their individual fitness and, ultimately, populations; and the
effectiveness of implemented mitigation measures. Taken together,
mitigation and monitoring comprise the Navy's integrated approach for
reducing environmental impacts from the specified activities. The
Navy's overall monitoring approach seeks to leverage and build on
existing research efforts whenever possible.
As agreed upon between the Navy and NMFS, the monitoring measures
presented here, as well as the mitigation measures described above,
focus on the protection and management of potentially affected marine
mammals. A well-designed monitoring program can provide important
feedback for validating assumptions made in analyses and allow for
adaptive management of marine resources. Monitoring is required under
the MMPA, and details of the monitoring program for the specified
activities have been developed through coordination between NMFS and
the Navy through the regulatory process for previous Navy at-sea
training and testing activities.
Integrated Comprehensive Monitoring Program (ICMP)
The Navy's ICMP is intended to coordinate marine species monitoring
efforts across all regions and to allocate the most appropriate level
and type of effort for each range complex based on a set of
standardized objectives, and in acknowledgement of regional expertise
and resource availability. The ICMP is designed to be flexible,
scalable, and adaptable through the adaptive management and strategic
planning processes to periodically assess progress and reevaluate
objectives. This process includes conducting an annual adaptive
management review meeting, at which the Navy and NMFS jointly consider
the prior-year goals, monitoring results, and related scientific
advances to determine if monitoring plan modifications are warranted to
more effectively address program goals. Although the ICMP does not
specify actual monitoring field work or individual projects, it does
establish a matrix of goals and objectives that have been developed in
coordination with NMFS. As the ICMP is implemented through the
Strategic Planning Process, detailed and specific studies will be
developed which support the Navy's and NMFS top-level monitoring goals.
In essence, the ICMP directs that monitoring activities relating to the
effects of Navy training and testing activities on marine species
should be designed to contribute towards one or more of the following
top-level goals:
[ssquf] An increase in our understanding of the likely occurrence
of marine mammals and/or ESA-listed marine species in the vicinity of
the action (i.e., presence, abundance, distribution, and/or density of
species);
[[Page 5871]]
[ssquf] An increase in our understanding of the nature, scope, or
context of the likely exposure of marine mammals and/or ESA-listed
species to any of the potential stressor(s) associated with the action
(e.g., sound, explosive detonation, or military expended materials)
through better understanding of one or more of the following: (1) The
action and the environment in which it occurs (e.g., sound source
characterization, propagation, and ambient noise levels); (2) the
affected species (e.g., life history or dive patterns); (3) the likely
co-occurrence of marine mammals and/or ESA-listed marine species with
the action (in whole or part); and/or (4) the likely biological or
behavioral context of exposure to the stressor for the marine mammal
and/or ESA-listed marine species (e.g., age class of exposed animals or
known pupping, calving or feeding areas);
[ssquf] An increase in our understanding of how individual marine
mammals or ESA-listed marine species respond (behaviorally or
physiologically) to the specific stressors associated with the action
(in specific contexts, where possible, e.g., at what distance or
received level);
[ssquf] An increase in our understanding of how anticipated
individual responses, to individual stressors or anticipated
combinations of stressors, may impact either: (1) The long-term fitness
and survival of an individual or (2) the population, species, or stock
(e.g., through effects on annual rates of recruitment or survival);
[ssquf] An increase in our understanding of the effectiveness of
mitigation and monitoring measures;
[ssquf] A better understanding and record of the manner in which
the Navy complies with the incidental take regulations and LOAs and the
ESA Incidental Take Statement;
[ssquf] An increase in the probability of detecting marine mammals
(through improved technology or methods), both specifically within the
mitigation zone (thus allowing for more effective implementation of the
mitigation) and in general, to better achieve the above goals; and
[ssquf] Ensuring that adverse impact of activities remains at the
least practicable level.
Strategic Planning Process for Marine Species Monitoring
The Navy also developed the Strategic Planning Process for Marine
Species Monitoring, which establishes the guidelines and processes
necessary to develop, evaluate, and fund individual projects based on
objective scientific study questions. The process uses an underlying
framework designed around intermediate scientific objectives and a
conceptual framework incorporating a progression of knowledge spanning
occurrence, exposure, response, and consequence. The Strategic Planning
Process for Marine Species Monitoring is used to set overarching
intermediate scientific objectives; develop individual monitoring
project concepts; identify potential species of interest at a regional
scale; evaluate, prioritize and select specific monitoring projects to
fund or continue supporting for a given fiscal year; execute and manage
selected monitoring projects; and report and evaluate progress and
results. This process addresses relative investments to different range
complexes based on goals across all range complexes, and monitoring
would leverage multiple techniques for data acquisition and analysis
whenever possible. The Strategic Planning Process for Marine Species
Monitoring is also available online (http://www.navymarinespeciesmonitoring.us/).
Past and Current Monitoring in the MITT Study Area
The monitoring program has undergone significant changes since the
first rule was issued for the MITT Study Area in 2009, which highlights
the monitoring program's evolution through the process of adaptive
management. The monitoring program developed for the first cycle of
environmental compliance documents (e.g., U.S. Department of the Navy,
2008) utilized effort-based compliance metrics that were somewhat
limiting. Through adaptive management discussions, the Navy designed
and conducted monitoring studies according to scientific objectives,
thereby eliminating basing requirements upon metrics of level-of-
effort. Furthermore, refinements of scientific objective have continued
through the latest permit cycle.
Progress has also been made on the conceptual framework categories
from the Scientific Advisory Group for Navy Marine Species Monitoring
(U.S. Department of the Navy, 2011c), ranging from occurrence of
animals, to their exposure, response, and population consequences. The
Navy continues to manage the Atlantic and Pacific program as a whole,
with monitoring in each range complex taking a slightly different but
complementary approach. The Navy has continued to use the approach of
layering multiple simultaneous components in many of the range
complexes to leverage an increase in return of the progress toward
answering scientific monitoring questions. This includes, in the
Marianas for example, (a) glider deployment in offshore areas, (b)
analysis of existing passive acoustic monitoring datasets, (c) small
boat surveys using visual, biopsy and satellite tagging and (d)
seasonal, humpback whale specific surveys.
Specific monitoring under the current regulations includes:
[ssquf] Review of the available data and analyses in the MITT Study
Area 2010 through February 2018 (2019a).
[ssquf] The continuation of annual small vessel nearshore surveys,
sightings, satellite tagging, biopsy and genetic analysis, photo-
identification, and opportunistic acoustic recording off Guam, Saipan,
Tinian, Rota, and Aguigan in partnership with NMFS (Hill et al., 2015;
Hill et al., 2016b; Hill et al., 2017a; Hill et al., 2018, Hill et al.,
2019b). The satellite tagging and genetic analyses have resulted in the
first information discovered on the movement patterns, habitat
preference, and population structure of multiple odontocete species in
the MITT Study Area.
[ssquf] Since 2015, the addition of a series of small vessel
surveys in the winter season dedicated to humpback whales has provided
new information relating to the occurrence, calving behavior, and
population identity of this species (Hill et al., 2016a; Hill et al.,
2017b), which had not previously been sighted during the previous small
vessel surveys in the summer or winter. This work has included sighting
data, photo ID matches of individuals to other areas demonstrating
migration as well as re-sights within the Marianas across different
years, and the collection of biopsy samples for genetic analyses of
populations.
[ssquf] The continued deployment of passive acoustic monitoring
devices and analysis of acoustic data obtained using bottom-moored
acoustic recording devices deployed by NMFS has provided information on
the presence and seasonal occurrence of mysticetes, as well as the
occurrence of cryptic odontocetes typically found offshore, including
beaked whales and Kogia spp. (Hill et al., 2015; Hill et al., 2016a;
Hill et al., 2016b; Hill et al., 2017a; Munger et al., 2015; Norris et
al., 2017; Oleson et al., 2015; Yack et al., 2016).
[ssquf] Acoustic surveys using autonomous gliders were used to
characterize the occurrence of odontocetes and mysticetes in abyssal
offshore waters near Guam and CNMI, including species not seen in the
small vessel visual survey series such as killer whales and Risso's
dolphins. Analysis of collected
[[Page 5872]]
data also provided new information on the seasonality of baleen whales,
patterns of beaked whale occurrence and potential call variability, and
identification of a new unknown marine mammal call (Klinck et al.,
2016b; Nieukirk et al., 2016).
[ssquf] Visual surveys were conducted from a shore-station at high
elevation on the north shore of Guam to document the nearshore
occurrence of marine mammals in waters where small vessel visual
surveys are challenging due to regularly high sea states (Deakos and
Richlen, 2015; Deakos et al., 2016).
[ssquf] Analysis of archive data that included marine mammal
sightings during Guam Department of Agriculture Division of Aquatic and
Wildlife Resources aerial surveys undertaken between 1963 and 2012
(Martin et al., 2016).
[ssquf] Analysis of archived acoustic towed-array data for an
assessment of the abundance and density of minke whales (Norris et al.,
2017), abundance and density of sperm whales (Yack et al., 2016), and
the characterization of sei and humpback whale vocalizations (Norris et
al., 2014).
Numerous publications, dissertations, and conference presentations
have resulted from research conducted under the Navy's marine species
monitoring program (https://www.navymarinespeciesmonitoring.us/reading-room/publications/), resulting in a significant contribution to the
body of marine mammal science. Publications on occurrence,
distribution, and density have fed the modeling input, and publications
on exposure and response have informed Navy and NMFS analyses of
behavioral response and consideration of mitigation measures.
Furthermore, collaboration between the monitoring program and the
Navy's research and development (e.g., the Office of Naval Research)
and demonstration-validation (e.g., Living Marine Resources) programs
has been strengthened, leading to research tools and products that have
already transitioned to the monitoring program. These include Marine
Mammal Monitoring on Ranges (M3R), controlled exposure experiment
behavioral response studies (CEE BRS), acoustic sea glider surveys, and
global positioning system-enabled satellite tags. Recent progress has
been made with better integration of monitoring across all Navy at-sea
study areas, including study areas in the Pacific and the Atlantic
Oceans, and various testing ranges. Publications from the Living Marine
Resources and the Office of Naval Research programs have also resulted
in significant contributions to information on hearing ranges and
acoustic criteria used in effects modeling, exposure, and response, as
well as developing tools to assess biological significance (e.g.,
population-level consequences).
NMFS and the Navy also consider data collected during procedural
mitigations as monitoring. Data are collected by shipboard personnel on
hours spent training, hours of observation, hours of sonar, and marine
mammals observed within the mitigation zones when mitigations are
implemented. These data are provided to NMFS in both classified and
unclassified annual exercise reports, which would continue under this
proposed rule.
NMFS has received multiple years' worth of annual exercise and
monitoring reports addressing active sonar use and explosive
detonations within the MITT Study Area and other Navy range complexes.
The data and information contained in these reports have been
considered in developing mitigation and monitoring measures for the
training and testing activities within the MITT Study Area. The Navy's
annual exercise and monitoring reports may be viewed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities and http://www.navymarinespeciesmonitoring.us.
Prior to Phase I monitoring, the information on marine mammal
presence and occurrence in the MIRC was largely absent and limited to
anecdotal information from incidental sightings and stranding events
(U.S. Department of the Navy, 2005). In 2007, the Navy funded the
Mariana Islands Sea Turtle and Cetacean Survey (MISTCS) (U.S.
Department of the Navy, 2007) to proactively support the baseline data
feeding the MIRC EIS (U.S. Department of the Navy, 2010b). The MISTCS
research effort was the first systematic marine survey in these waters.
This survey provided the first empirically-based density estimates for
marine mammals (Fulling et al., 2011). In cooperation with NMFS, the
Phase I monitoring program beginning in 2010 was designed to address
basic occurrence-level questions in the MIRC, whereas monitoring the
impacts of Navy training such as exposure to mid-frequency active sonar
was planned for other Navy range complexes where marine mammal
occurrence was already better characterized.
This emphasis on studying occurrence continued through Phase I and
II monitoring in the MIRC, and combined various complementary
methodologies. Small vessel visual surveys collected occurrence
information, and began building the first individual identification
catalog for multiple species (Hill et al., 2014). During these visual
surveys, biopsies were collected for genetic analysis and satellite
tags were also applied, resulting in a progressively improving picture
of the habitat use and population structure of various species. Deep
water passive acoustic deployments, including autonomous gliders with
passive acoustic recorders, added complementary information on species
groups such as baleen whales and beaked whales that were rarely sighted
on the vessel surveys (Klinck et al., 2015; Munger et al., 2014; Munger
et al., 2015; Nieukirk et al., 2016; Norris et al., 2015). Other
methodologies were also explored to fill other gaps in waters generally
inaccessible to the small boat surveys including a shore-station to
survey waters on the windward side of Guam (Deakos et al., 2016). When
available, platforms of opportunity on large vessels were utilized for
visual survey and tagging (Oleson and Hill, 2010b).
At the close of Phase II monitoring, establishing the fundamentals
of marine mammal occurrence in the MITT Study Area has now been largely
completed. The various visual and acoustic platforms have encountered
nearly all of the species that are expected to occur in the MITT Study
Area. The photographic catalogs have progressively grown to the point
that abundance analyses may be attempted for the most commonly-
encountered species. Beyond occurrence, questions related to exposure
to Navy training have been addressed, such as utilizing satellite tag
telemetry to evaluate overlap of habitat use with underwater detonation
training sites. Also during Phase II monitoring, a pilot study to
investigate reports of humpback whales occasionally occurring off
Saipan has proven fruitful, yielding confirmation of this species
there, photographic matches of individuals to other waters in the
Pacific Ocean, as well as genetics data that provide clues as to the
population identity of these animals (Hill et al., 2016a; Hill et al.,
2017b). Importantly, the compiled data were also used to inform
proposals for new mitigation areas for this proposed rule and
associated consultations.
The ongoing regional species-specific study questions and results
from recent efforts are publicly available on the Navy's Monitoring
Program website. With basic occurrence information now well-
established, the primary goal of monitoring in the MITT Study Area
[[Page 5873]]
under this proposed rule would be to close out these studies with final
analyses. As the collection and analysis of basic occurrence data
across Navy ranges (including MITT) is completed, the focus of
monitoring across all Navy range complexes will progressively move
toward addressing the important questions of exposure and response to
mid-frequency active sonar and other Navy training, as well as the
consequences of those exposures, where appropriate. The Navy's
hydrophone-instrumented ranges have proven to be a powerful tool
towards this end and because of the lack of such an instrumented range
in the MITT Study Area, monitoring investments are expected to begin
shifting to other Navy range complexes as the currently ongoing
research efforts in the Mariana Islands are completed. Any future
monitoring results for the MITT Study Area will continue to be
published on the Navy's Monitoring Program website, as well as
discussed during annual adaptive management meetings between NMFS and
the Navy.
The Navy's marine species monitoring program typically supports
several monitoring projects in the MITT Study Area at any given time.
Additional details on the scientific objectives for each project can be
found at https://www.navymarinespeciesmonitoring.us/regions/pacific/current-projects/. Projects can be either major multi-year efforts, or
one to two-year special studies. The Navy's proposed monitoring
projects going into 2020 include:
[ssquf] Significant funding to NMFS' Pacific Island Fisheries
Science Center (PIFSC) for spring-summer 2021 large vessel visual and
acoustic survey through the Mariana Islands;
[ssquf] Humpback whale visual survey at FDM;
[ssquf] Continued coordination with NMFS PIFSC for small boat
humpback whale surveys at other Mariana Islands (e.g., Saipan);
[ssquf] Analysis of previously deployed passive acoustic sensors
for detection of humpback whale vocalizations at other islands (e.g..
Pagan);
[ssquf] Funding to support long-term (weeks-months) satellite tag
tracking of humpback whales (field work likely in winter 2021); and
[ssquf] Funding to researchers with PIFSC for detailed necropsy
support for select stranded marine mammals in Hawaii and the Mariana
Islands.
Adaptive Management
The proposed regulations governing the take of marine mammals
incidental to Navy training and testing activities in the MITT Study
Area contain an adaptive management component. Our understanding of the
effects of Navy training and testing activities (e.g., acoustic and
explosive stressors) on marine mammals continues to evolve, which makes
the inclusion of an adaptive management component both valuable and
necessary within the context of seven-year regulations.
The reporting requirements associated with this rule are designed
to provide NMFS with monitoring data from the previous year to allow
NMFS to consider whether any changes to existing mitigation and
monitoring requirements are appropriate. The use of adaptive management
allows NMFS to consider new information from different sources to
determine (with input from the Navy regarding practicability) on an
annual or biennial basis if mitigation or monitoring measures should be
modified (including additions or deletions). Mitigation measures could
be modified if new data suggests that such modifications would have a
reasonable likelihood of more effectively accomplishing the goals of
the mitigation and monitoring and if the measures are practicable. If
the modifications to the mitigation, monitoring, or reporting measures
are substantial, NMFS would publish a notice of the planned LOA in the
Federal Register and solicit public comment.
The following are some of the possible sources of applicable data
to be considered through the adaptive management process: (1) Results
from monitoring and exercises reports, as required by MMPA
authorizations; (2) compiled results of Navy funded R&D studies; (3)
results from specific stranding investigations; (4) results from
general marine mammal and sound research; and (5) any information which
reveals that marine mammals may have been taken in a manner, extent, or
number not authorized by these regulations or subsequent LOAs. The
results from monitoring reports and other studies may be viewed at
https://www.navymarinespeciesmonitoring.us.
Proposed Reporting
In order to issue incidental take authorization for an activity,
section 101(a)(5)(A) of the MMPA states that NMFS must set forth
requirements pertaining to the monitoring and reporting of such taking.
Effective reporting is critical both to compliance as well as ensuring
that the most value is obtained from the required monitoring. Reports
from individual monitoring events, results of analyses, publications,
and periodic progress reports for specific monitoring projects will be
posted to the Navy's Marine Species Monitoring web portal: http://www.navymarinespeciesmonitoring.us.
Currently, there are several different reporting requirements
pursuant to the regulations. All of these reporting requirements would
be continued under this proposed rule for the seven-year period.
Notification of Injured, Live Stranded or Dead Marine Mammals
The Navy would consult the Notification and Reporting Plan, which
sets out notification, reporting, and other requirements when injured,
live stranded, or dead marine mammals are detected. The Notification
and Reporting Plan is available for review at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
Annual MITT Monitoring Report
The Navy would submit an annual report to NMFS of the MITT
monitoring describing the implementation and results from the previous
calendar year. Data collection methods would be standardized across
Pacific Range Complexes including the MITT, HSTT, NWTT, and GOA Study
Areas to allow for comparison in different geographic locations. The
draft of the annual monitoring report would be submitted either three
months after the end of the calendar year or three months after the
conclusion of the monitoring year, to be determined by the Adaptive
Management process. Such a report would describe progress of knowledge
made with respect to intermediate scientific objectives within the MITT
Study Area associated with the Integrated Comprehensive Monitoring
Program. Similar study questions would be treated together so that
summaries can be provided for each topic area. The report need not
include analyses and content that do not provide direct assessment of
cumulative progress on the monitoring plan study questions. NMFS would
submit comments on the draft monitoring report, if any, within three
months of receipt. The report would be considered final after the Navy
has addressed NMFS' comments, or three months after the submittal of
the draft if NMFS does not have comments.
As an alternative, the Navy may submit a Pacific-Range Complex
annual Monitoring Plan report to fulfill this requirement. Such a
report describes progress of knowledge made with respect to monitoring
study questions across multiple Navy ranges associated
[[Page 5874]]
with the ICMP. Similar study questions would be treated together so
that progress on each topic is summarized across multiple Navy ranges.
The report need not include analyses and content that does not provide
direct assessment of cumulative progress on the monitoring study
question. This would continue to allow Navy to provide a cohesive
monitoring report covering multiple ranges (as per ICMP goals), rather
than entirely separate reports for the HSTT, Gulf of Alaska, Mariana
Islands, and the Northwest Study Areas.
Annual MITT Training Exercise Report and Testing Activity Reports
Each year, the Navy would submit one preliminary report (Quick Look
Report) to NMFS detailing the status of authorized sound sources within
21 days after the anniversary of the date of issuance of the LOA. Each
year, the Navy would also a submit detailed report (MITT Annual
Training Exercise Report and Testing Activity Report) to NMFS within
three months after the one-year anniversary of the date of issuance of
the LOA. The annual report would contain information on MTEs, Sinking
Exercise (SINKEX) events, and a summary of all sound sources used
(total hours or quantity (per the LOA) of each bin of sonar or other
non-impulsive source; total annual number of each type of explosive
exercises; and total annual expended/detonated rounds (missiles, bombs,
sonobuoys, etc.) for each explosive bin). The annual report will also
contain cumulative sonar and explosive use quantity from previous
years' reports through the current year. Additionally, if there were
any changes to the sound source allowance in the reporting year, or
cumulatively, the report would include a discussion of why the change
was made and include analysis to support how the change did or did not
affect the analysis in the MITT EIS/OEIS and MMPA final rule. The
annual report would also include the details regarding specific
requirements associated with specific mitigation areas. The analysis in
the detailed report would be based on the accumulation of data from the
current year's report and data collected from previous annual reports.
The final annual/close-out report at the conclusion of the
authorization period (year seven) would also serve as the comprehensive
close-out report and include both the final year annual use compared to
annual authorization as well as a cumulative seven-year annual use
compared to seven-year authorization. Information included in the
annual reports may be used to inform future adaptive management of
activities within the MITT Study Area.
The Annual MITT Training Exercise Report and Testing Activity Navy
report (classified or unclassified versions) could be consolidated with
other exercise reports from other range complexes in the Pacific Ocean
for a single Pacific Exercise Report, if desired. Specific sub-
reporting in these annual reports would include:
[ssquf] Marpi Reef and Chalan Kanoa Reef Geographic Mitigation
Areas: The Navy would report the total hours of operation of MF1
surface ship hull-mounted mid-frequency active sonar used in the Marpi
Reef and Chalan Kanoa Reef Geographic Mitigation Areas from December to
April; and
[ssquf] Major Training Exercises Notification
The Navy would submit an electronic report to NMFS within fifteen
calendar days after the completion of any major training exercise
indicating: Location of the exercise; beginning and end dates of the
exercise; and type of exercise.
Other Reporting and Coordination
The Navy would continue to report and coordinate with NMFS for the
following:
[ssquf] Annual marine species monitoring technical review meetings
that also include researchers and the Marine Mammal Commission
(currently, every two years a joint Pacific-Atlantic meeting is held);
and
[ssquf] Annual Adaptive Management meetings that also include the
Marine Mammal Commission (recently modified to occur in conjunction
with the annual monitoring technical review meeting).
Preliminary Analysis and Negligible Impact Determination
General Negligible Impact Analysis
Introduction
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
taken by Level A or Level B harassment (as presented in Table 30), NMFS
considers other factors, such as the likely nature of any responses
(e.g., intensity, duration), the context of any responses (e.g.,
critical reproductive time or location, migration), as well as effects
on habitat, and the likely effectiveness of the mitigation. We also
assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338;
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the environmental baseline (e.g., as reflected in the
regulatory status of the species, population size and growth rate where
known, other ongoing sources of human-caused mortality, and ambient
noise levels).
In the Estimated Take of Marine Mammals section, we identified the
subset of potential effects that would be expected to rise to the level
of takes both annually and over the seven-year period covered by this
proposed rule, and then identified the maximum number of harassment
takes that are reasonably expected to occur based on the methods
described. The impact that any given take will have is dependent on
many case-specific factors that need to be considered in the negligible
impact analysis (e.g., the context of behavioral exposures such as
duration or intensity of a disturbance, the health of impacted animals,
the status of a species that incurs fitness-level impacts to
individuals, etc.). For this proposed rule we evaluated the likely
impacts of the enumerated maximum number of harassment takes that are
proposed for authorization and reasonably expected to occur, in the
context of the specific circumstances surrounding these predicted
takes. Last, we collectively evaluated this information, as well as
other more taxa-specific information and mitigation measure
effectiveness, in group-specific assessments that support our
negligible impact conclusions for each species.
As explained in the Estimated Take of Marine Mammals section, no
take by serious injury or mortality is requested or anticipated to
occur.
The Specified Activities reflect representative levels of training
and testing activities. The Description of the Specified Activity
section describes annual activities. There may be some flexibility in
the exact number of hours, items, or detonations that may vary from
year to year, but take totals would not exceed the seven-year totals
indicated in Table 30. We base our analysis and negligible impact
determination on the
[[Page 5875]]
maximum number of takes that would be reasonably expected to occur and
are proposed to be authorized, although, as stated before, the number
of takes are only a part of the analysis, which includes extensive
qualitative consideration of other contextual factors that influence
the degree of impact of the takes on the affected individuals. To avoid
repetition, we provide some general analysis immediately below that
applies to all the species listed in Table 30, given that some of the
anticipated effects of the Navy's training and testing activities on
marine mammals are expected to be relatively similar in nature.
However, below that, we break our analysis into species, or groups of
species where relevant similarities exist, to provide more specific
information related to the anticipated effects on individuals or where
there is information about the status or structure of any species that
would lead to a differing assessment of the effects on the species.
Organizing our analysis by grouping species that share common traits or
that will respond similarly to effects of the Navy's activities and
then providing species-specific information allows us to avoid
duplication while assuring that we have analyzed the effects of the
specified activities on each affected species.
The Navy's harassment take request is based on its model and
quantitative assessment of mitigation, which NMFS reviewed and concurs,
and appropriately predicts the maximum amount of harassment that is
likely to occur. The model calculates sound energy propagation from
sonar, other active acoustic sources, and explosives during naval
activities; the sound or impulse received by animat dosimeters
representing marine mammals distributed in the area around the modeled
activity; and whether the sound or impulse energy received by a marine
mammal exceeds the thresholds for effects. Assumptions in the Navy
model intentionally err on the side of overestimation when there are
unknowns. Naval activities are modeled as though they would occur
regardless of proximity to marine mammals, meaning that no mitigation
is considered (e.g., no power down or shut down) and without any
avoidance of the activity by the animal. The final step of the
quantitative analysis of acoustic effects, which occurs after the
modeling, is to consider the implementation of mitigation and the
possibility that marine mammals would avoid continued or repeated sound
exposures. NMFS provided input to, independently reviewed, and
concurred with the Navy on this process and the Navy's analysis, which
is described in detail in Section 6 of the Navy's rulemaking/LOA
application, was used to quantify harassment takes for this rule.
Generally speaking, the Navy and NMFS anticipate more severe
effects from takes resulting from exposure to higher received levels
(though this is in no way a strictly linear relationship for behavioral
effects throughout species, individuals, or circumstances) and less
severe effects from takes resulting from exposure to lower received
levels. However, there is also growing evidence of the importance of
distance in predicting marine mammal behavioral response to sound--
i.e., sounds of a similar level emanating from a more distant source
have been shown to be less likely to evoke a response of equal
magnitude (DeRuiter 2012). The estimated number of Level A and Level B
harassment takes does not equate to the number of individual animals
the Navy expects to harass (which is lower), but rather to the
instances of take (i.e., exposures above the Level A and Level B
harassment threshold) that are anticipated to occur over the seven-year
period. These instances may represent either brief exposures (seconds
or minutes) or, in some cases, longer durations of exposure within a
day. Some individuals may experience multiple instances of take
(meaning over multiple days) over the course of the year, which means
that the number of individuals taken is smaller than the total
estimated takes. Generally speaking, the higher the number of takes as
compared to the population abundance, the more repeated takes of
individuals are likely, and the higher the actual percentage of
individuals in the population that are likely taken at least once in a
year. We look at this comparative metric to give us a relative sense of
where a larger portion of a species is being taken by Navy activities,
where there is a higher likelihood that the same individuals are being
taken across multiple days, and where that number of days might be
higher or more likely sequential. Where the number of instances of take
is less than 100 percent of the abundance and there is no information
to specifically suggest that a small subset of animals is being
repeatedly taken over a high number of sequential days, the overall
magnitude is generally considered relatively low, as it could on one
extreme mean that every individual in the population will be taken on
one day (a very minimal impact) or, more likely, that some are taken on
one day annually, some are taken on a few not likely sequential days
annually, and some are not taken at all.
In the ocean, the use of sonar and other active acoustic sources is
often transient and is unlikely to repeatedly expose the same
individual animals within a short period, for example within one
specific exercise. However, for some individuals of some species
repeated exposures across different activities could occur over the
year, especially where events occur in generally the same area with
more resident species. In short, for some species we expect that the
total anticipated takes represent exposures of a smaller number of
individuals of which some were exposed multiple times, but based on the
nature of the Navy activities and the movement patterns of marine
mammals, it is unlikely that individuals from most species would be
taken over more than a few sequential days. This means that even where
repeated takes of individuals are likely to occur, they are more likely
to result from non-sequential exposures from different activities, and,
even if sequential, individual animals are not predicted to be taken
for more than several days in a row, at most. As described elsewhere,
the nature of the majority of the exposures would be expected to be of
a less severe nature and based on the numbers it is likely that any
individual exposed multiple times is still only taken on a small
percentage of the days of the year. The greater likelihood is that not
every individual is taken, or perhaps a smaller subset is taken with a
slightly higher average and larger variability of highs and lows, but
still with no reason to think that any individuals would be taken a
significant portion of the days of the year, much less that many of the
days of disturbance would be sequential.
Physiological Stress Response
Some of the lower level physiological stress responses (e.g.,
orientation or startle response, change in respiration, change in heart
rate) discussed earlier would likely co-occur with the predicted
harassments, although these responses are more difficult to detect and
fewer data exist relating these responses to specific received levels
of sound. Level B harassment takes, then, may have a stress-related
physiological component as well; however, we would not expect the
Navy's generally short-term, intermittent, and (typically in the case
of sonar) transitory activities to create conditions of long-term,
continuous noise leading to long-term physiological stress responses in
marine
[[Page 5876]]
mammals that could affect reproduction or survival.
Behavioral Response
The estimates calculated using the behavioral response function do
not differentiate between the different types of behavioral responses
that rise to the level of Level B harassments. As described in the
Navy's application, the Navy identified (with NMFS' input) the types of
behaviors that would be considered a take (moderate behavioral
responses as characterized in Southall et al. (2007) (e.g., altered
migration paths or dive profiles, interrupted nursing, breeding or
feeding, or avoidance) that also would be expected to continue for the
duration of an exposure). The Navy then compiled the available data
indicating at what received levels and distances those responses have
occurred, and used the indicated literature to build biphasic
behavioral response curves that are used to predict how many instances
of Level B behavioral harassment occur in a day. Take estimates alone
do not provide information regarding the potential fitness or other
biological consequences of the reactions on the affected individuals.
We therefore consider the available activity-specific, environmental,
and species-specific information to determine the likely nature of the
modeled behavioral responses and the potential fitness consequences for
affected individuals.
Use of sonar and other transducers would typically be transient and
temporary. The majority of acoustic effects to individual animals from
sonar and other active sound sources during testing and training
activities would be primarily from ASW events. It is important to note
that although ASW is one of the warfare areas of focus during MTEs,
there are significant periods when active ASW sonars are not in use.
Nevertheless, behavioral reactions are assumed more likely to be
significant during MTEs than during other ASW activities due to the
duration (i.e., multiple days), scale (i.e., multiple sonar platforms),
and use of high-power hull-mounted sonar in the MTEs. In other words,
in the range of potential behavioral effects that might expect to be
part of a response that qualifies as an instance of Level B behavioral
harassment (which by nature of the way it is modeled/counted, occurs
within one day), the less severe end might include exposure to
comparatively lower levels of a sound, at a detectably greater distance
from the animal, for a few or several minutes. A less severe exposure
of this nature could result in a behavioral response such as avoiding
an area that an animal would otherwise have chosen to move through or
feed in for some amount of time or breaking off one or a few feeding
bouts. More severe effects could occur when the animal gets close
enough to the source to receive a comparatively higher level, is
exposed continuously to one source for a longer time, or is exposed
intermittently to different sources throughout a day. Such effects
might result in an animal having a more severe flight response and
leaving a larger area for a day or more or potentially losing feeding
opportunities for a day. However, such severe behavioral effects are
expected to occur infrequently.
To help assess this, for sonar (LFAS/MFAS/HFAS) used in the MITT
Study Area, the Navy provided information estimating the percentage of
animals that may be taken by Level B harassment under each behavioral
response function that would occur within 6-dB increments (percentages
discussed below in the Group and Species-Specific Analyses section). As
mentioned above, all else being equal, an animal's exposure to a higher
received level is more likely to result in a behavioral response that
is more likely to lead to adverse effects, which could more likely
accumulate to impacts on reproductive success or survivorship of the
animal, but other contextual factors (such as distance) are important
also. The majority of Level B harassment takes are expected to be in
the form of milder responses (i.e., lower-level exposures that still
rise to the level of take, but would likely be less severe in the range
of responses that qualify as take) of a generally shorter duration. We
anticipate more severe effects from takes when animals are exposed to
higher received levels or at closer proximity to the source. Because
species belonging to taxa that share common characteristics are likely
to respond and be affected in similar ways, these discussions are
presented within each species group below in the Group and Species-
Specific Analyses section. As noted previously in this proposed rule,
behavioral response is likely highly variable between species,
individuals within a species, and context of the exposure.
Specifically, given a range of behavioral responses that may be
classified as Level B harassment, to the degree that higher received
levels are expected to result in more severe behavioral responses, only
a smaller percentage of the anticipated Level B harassment from Navy
activities might necessarily be expected to potentially result in more
severe responses (see the Group and Species-Specific Analyses section
below for more detailed information). To fully understand the likely
impacts of the predicted/proposed authorized take on an individual
(i.e., what is the likelihood or degree of fitness impacts), one must
look closely at the available contextual information, such as the
duration of likely exposures and the likely severity of the exposures
(e.g., whether they will occur for a longer duration over sequential
days or the comparative sound level that will be received). Moore and
Barlow (2013) emphasizes the importance of context (e.g., behavioral
state of the animals, distance from the sound source, etc.) in
evaluating behavioral responses of marine mammals to acoustic sources.
Diel Cycle
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing on a diel cycle (24-hour cycle). Behavioral
reactions to noise exposure, when taking place in a biologically
important context, such as disruption of critical life functions,
displacement, or avoidance of important habitat, are more likely to be
significant if they last more than one diel cycle or recur on
subsequent days (Southall et al., 2007). Henderson et al. (2016) found
that ongoing smaller scale events had little to no impact on foraging
dives for Blainville's beaked whale, while multi-day training events
may decrease foraging behavior for Blainville's beaked whale (Manzano-
Roth et al., 2016). Consequently, a behavioral response lasting less
than one day and not recurring on subsequent days is not considered
severe unless it could directly affect reproduction or survival
(Southall et al., 2007). Note that there is a difference between
multiple-day substantive behavioral reactions and multiple-day
anthropogenic activities. For example, just because an at-sea exercise
lasts for multiple days does not necessarily mean that individual
animals are either exposed to those exercises for multiple days or,
further, exposed in a manner resulting in a sustained multiple day
substantive behavioral response. Large multi-day Navy exercises such as
ASW activities, typically include vessels that are continuously moving
at speeds typically 10-15 kn, or higher, and likely cover large areas
that are relatively far from shore (typically more than 3 NM from
shore) and in waters greater than 600 ft deep. Additionally marine
mammals are moving as well, which would make it unlikely that the same
animal could remain in the immediate vicinity of the ship for the
entire duration of the exercise. Further, the Navy does not
[[Page 5877]]
necessarily operate active sonar the entire time during an exercise.
While it is certainly possible that these sorts of exercises could
overlap with individual marine mammals multiple days in a row at levels
above those anticipated to result in a take, because of the factors
mentioned above, it is considered unlikely for the majority of takes.
However, it is also worth noting that the Navy conducts many different
types of noise-producing activities over the course of the year and it
is likely that some marine mammals will be exposed to more than one and
taken on multiple days, even if they are not sequential.
That said, the MITT Study Area is different than other Navy ranges
where there can be a significant number of Navy surface ships with
hull-mounted sonar homeported. In the MITT Study Area, there are no
homeported surface ships with hull-mounted sonars permanently assigned.
There is no local unit level training in the MITT Study Area for
homeported ships such as the case for other ranges. Instead, Navy
activities from visiting and transiting vessels are much more episodic
in the MITT Study Area. Therefore, there could be long gaps between
activities (i.e., weeks, months) in the MITT Study Area.
Durations of Navy activities utilizing tactical sonar sources and
explosives vary and are fully described in Appendix A (Training and
Testing Activity Descriptions) of the 2019 MITT DSEIS/OEIS. Sonar used
during ASW would impart the greatest amount of acoustic energy of any
category of sonar and other transducers analyzed in the Navy's
rulemaking/LOA application and include hull-mounted, towed, line array,
sonobuoy, helicopter dipping, and torpedo sonars. Most ASW sonars are
MFAS (1-10 kHz); however, some sources may use higher or lower
frequencies. ASW training activities using hull mounted sonar proposed
for the MITT Study Area generally last for only a few hours. Some ASW
training and testing can generally last for 2-10 days, or a 10-day
exercise is typical for an MTE-Large Integrated ASW (see Table 3). For
these multi-day exercises there will typically be extended intervals of
non-activity in between active sonar periods. Because of the need to
train in a large variety of situations, the Navy does not typically
conduct successive ASW exercises in the same locations. Given the
average length of ASW exercises (times of sonar use) and typical vessel
speed, combined with the fact that the majority of the cetaceans would
not likely remain in proximity to the sound source, it is unlikely that
an animal would be exposed to LFAS/MFAS/HFAS at levels or durations
likely to result in a substantive response that would then be carried
on for more than one day or on successive days.
Most planned explosive events are scheduled to occur over a short
duration (1-8 hours); however, the explosive component of the activity
only lasts for minutes (see Table 3). Although explosive exercises may
sometimes be conducted in the same general areas repeatedly, because of
their short duration and the fact that they are in the open ocean and
animals can easily move away, it is similarly unlikely that animals
would be exposed for long, continuous amounts of time, or demonstrate
sustained behavioral responses. Although SINKEXs may last for up to 48
hrs (4-8 hrs, possibly 1-2 days), they are almost always completed in a
single day and only one event is planned annually for the MITT training
activities. They are stationary and conducted in deep, open water where
fewer marine mammals would typically be expected to be encountered.
They also have shutdown procedures and rigorous monitoring, i.e.,
during the activity, the Navy conducts passive acoustic monitoring and
visually observes for marine mammals 90 min prior to the first firing,
during the event, and 2 hrs after sinking the vessel. All of these
factors make it unlikely that individuals would be exposed to the
exercise for extended periods or on consecutive days.
Assessing the Number of Individuals Taken and the Likelihood of
Repeated Takes
As described previously, Navy modeling uses the best available
science to predict the instances of exposure above certain acoustic
thresholds, which are equated, as appropriate, to harassment takes (and
further corrected to account for mitigation and avoidance). As further
noted, for active acoustics it is more challenging to parse out the
number of individuals taken by Level B harassment and the number of
times those individuals are taken from this larger number of instances.
One method that NMFS can use to help better understand the overall
scope of the impacts is to compare these total instances of take
against the abundance of that species (or stock if applicable). For
example, if there are 100 harassment takes in a population of 100, one
can assume either that every individual was exposed above acoustic
thresholds in no more than one day, or that some smaller number were
exposed in one day but a few of those individuals were exposed multiple
days within a year. Where the instances of take exceed 100 percent of
the population, multiple takes of some individuals are predicted and
expected to occur within a year. Generally speaking, the higher the
number of takes as compared to the population abundance, the more
multiple takes of individuals are likely, and the higher the actual
percentage of individuals in the population that are likely taken at
least once in a year. We look at this comparative metric to give us a
relative sense of where larger portions of the species are being taken
by Navy activities and where there is a higher likelihood that the same
individuals are being taken across multiple days and where that number
of days might be higher. It also provides a relative picture of the
scale of impacts to each species.
In the ocean, unlike a modeling simulation with static animals, the
use of sonar and other active acoustic sources is often transient, and
is unlikely to repeatedly expose the same individual animals within a
short period, for example within one specific exercise. However, some
repeated exposures across different activities could occur over the
year with more resident species. Nonetheless, the episodic nature of
Navy activities in the MITT Study Area would mean less frequent
exposures as compared to some other ranges. While select offshore areas
in the MITT Study Area are used more frequently for ASW and other
activities, these are generally further offshore than where most island
associated resident population would occur and instead would be in
areas with more transitory species. In short, we expect that the total
anticipated takes represent exposures of a smaller number of
individuals of which some could be exposed multiple times, but based on
the nature of the Navy's activities and the movement patterns of marine
mammals, it is unlikely that any particular subset would be taken over
more than several sequential days (with a few possible exceptions
discussed in the species-specific conclusions).
When calculating the proportion of a population affected by takes
(e.g., the number of takes divided by population abundance), which can
also be helpful in estimating the number of days over which some
individuals may be taken, it is important to choose an appropriate
population estimate against which to make the comparison. The SARs,
where available, provide the official population estimate for a given
species or stock in U.S. waters in a given year (and are typically
based solely on the most recent survey data). When the stock is known
to range well outside of U.S. EEZ boundaries, population
[[Page 5878]]
estimates based on surveys conducted only within the U.S. EEZ are known
to be underestimates. For marine mammal populations in the MITT Study
Area there have been no specific stocks assigned to those populations
and there are no associated SARs. There is also no information on
trends for any of these species. The information used to estimate take
includes the best available survey abundance data to model density
layers. Accordingly, in calculating the percentage of takes versus
abundance for each species in order to assist in understanding both the
percentage of the species affected, as well as how many days across a
year individuals could be taken, we use the data most appropriate for
the situation. The survey data used to calculate abundance in the MITT
Study Area is described in the Navy Marine Species Density Database
Phase III for the Mariana Islands Training and Testing Study Area (Navy
2018). Models may predict different population abundances for many
reasons. The models may be based on different data sets or different
temporal predictions may be made. For example, the SARs are often based
on single years of NMFS surveys, whereas the models used by the Navy
generally include multiple years of survey data from NMFS, the Navy,
and other sources. To present a single, best estimate, the SARs often
use a single season survey where they have the best spatial coverage
(generally Summer). Navy models often use predictions for multiple
seasons, where appropriate for the species, even when survey coverage
in non-Summer seasons is limited, to characterize impacts over multiple
seasons as Navy activities may occur in any season. Predictions may be
made for different spatial extents. Many different, but equally valid,
habitat and density modeling techniques exist and these can also be the
cause of differences in population predictions.
Temporary Threshold Shift
NMFS and the Navy have estimated that all species of marine mammals
may sustain some level of TTS from active sonar. As mentioned
previously, in general, TTS can last from a few minutes to days, be of
varying degree, and occur across various frequency bandwidths, all of
which determine the severity of the impacts on the affected individual,
which can range from minor to more severe. Tables 51-55 indicates the
number of takes by TTS that may be incurred by different species from
exposure to active sonar and explosives. The TTS sustained by an animal
is primarily classified by three characteristics:
1. Frequency--Available data (of mid-frequency hearing specialists
exposed to mid- or high-frequency sounds; Southall et al., 2007)
suggest that most TTS occurs in the frequency range of the source up to
one octave higher than the source (with the maximum TTS at \1/2\ octave
above). The Navy's MF sources, which are the highest power and most
numerous sources and the ones that cause the most take, utilize the 1-
10 kHz frequency band, which suggests that if TTS were to be induced by
any of these MF sources it would be in a frequency band somewhere
between approximately 2 and 20 kHz, which is in the range of
communication calls for many odontocetes, but below the range of the
echolocation signals used for foraging. There are fewer hours of HF
source use and the sounds would attenuate more quickly, plus they have
lower source levels, but if an animal were to incur TTS from these
sources, it would cover a higher frequency range (sources are between
10 and 100 kHz, which means that TTS could range up to 200 kHz), which
could overlap with the range in which some odontocetes communicate or
echolocate. However, HF systems are typically used less frequently and
for shorter time periods than surface ship and aircraft MF systems, so
TTS from these sources is unlikely. There are fewer LF sources and the
majority are used in the more readily mitigated testing environment,
and TTS from LF sources would most likely occur below 2 kHz, which is
in the range where many mysticetes communicate and also where other
non-communication auditory cues are located (waves, snapping shrimp,
fish prey). Also of note, the majority of sonar sources from which TTS
may be incurred occupy a narrow frequency band, which means that the
TTS incurred would also be across a narrower band (i.e., not affecting
the majority of an animal's hearing range). This frequency provides
information about the cues to which a marine mammal may be temporarily
less sensitive, but not the degree or duration of sensitivity loss. TTS
from explosives would be broadband.
2. Degree of the shift (i.e., by how many dB the sensitivity of the
hearing is reduced)--Generally, both the degree of TTS and the duration
of TTS will be greater if the marine mammal is exposed to a higher
level of energy (which would occur when the peak dB level is higher or
the duration is longer). The threshold for the onset of TTS was
discussed previously in this rule. An animal would have to approach
closer to the source or remain in the vicinity of the sound source
appreciably longer to increase the received SEL, which would be
difficult considering the Lookouts and the nominal speed of an active
sonar vessel (10-15 kn) and the relative motion between the sonar
vessel and the animal. In the TTS studies discussed in the proposed
rule, some using exposures of almost an hour in duration or up to 217
SEL, most of the TTS induced was 15 dB or less, though Finneran et al.
(2007) induced 43 dB of TTS with a 64-second exposure to a 20 kHz
source. However, since any hull-mounted sonar such as the SQS-53
(MFAS), emits a ping typically every 50 seconds, incurring those levels
of TTS is highly unlikely. Since any hull-mounted sonar, such as the
SQS-53, engaged in anti-submarine warfare training would be moving at
between 10 and 15 knots and nominally pinging every 50 seconds, the
vessel will have traveled a minimum distance of approximately 257 m
during the time between those pings. A scenario could occur where an
animal does not leave the vicinity of a ship or travels a course
parallel to the ship, however, the close distances required make TTS
exposure unlikely. For a Navy vessel moving at a nominal 10 knots, it
is unlikely a marine mammal could maintain speed parallel to the ship
and receive adequate energy over successive pings to suffer TTS.
In short, given the anticipated duration and levels of sound
exposure, we would not expect marine mammals to incur more than
relatively low levels of TTS (i.e., single digits of sensitivity loss).
To add context to this degree of TTS, individual marine mammals may
regularly experience variations of 6dB differences in hearing
sensitivity across time (Finneran et al., 2000, 2002; Schlundt et al.,
2000).
3. Duration of TTS (recovery time)--In the TTS laboratory studies
(as discussed in the proposed rule), some using exposures of almost an
hour in duration or up to 217 SEL, almost all individuals recovered
within 1 day (or less, often in minutes), although in one study
(Finneran et al., 2007), recovery took 4 days.
Based on the range of degree and duration of TTS reportedly induced
by exposures to non-pulse sounds of energy higher than that to which
free-swimming marine mammals in the field are likely to be exposed
during LFAS/MFAS/HFAS training and testing exercises in the MITT Study
Area, it is unlikely that marine mammals would ever sustain a TTS from
MFAS that alters their sensitivity by more than 20 dB for more than a
few hours--and any incident of TTS would likely be far less severe due
to the short duration of the
[[Page 5879]]
majority of the events and the speed of a typical vessel, especially
given the fact that the higher power sources resulting in TTS are
predominantly intermittent, which have been shown to result in shorter
durations of TTS. Also, for the same reasons discussed in the
Preliminary Analysis and Negligible Impact Determination--Diel Cycle
section, and because of the short distance within which animals would
need to approach the sound source, it is unlikely that animals would be
exposed to the levels necessary to induce TTS in subsequent time
periods such that their recovery is impeded. Additionally, though the
frequency range of TTS that marine mammals might sustain would overlap
with some of the frequency ranges of their vocalization types, the
frequency range of TTS from MFAS would not usually span the entire
frequency range of one vocalization type, much less span all types of
vocalizations or other critical auditory cues.
Tables 51-55 indicates the number of incidental takes by TTS for
each species that are likely to result from the Navy's activities. As a
general point, the majority of these TTS takes are the result of
exposure to hull-mounted MFAS (MF narrower band sources), with fewer
from explosives (broad-band lower frequency sources), and even fewer
from LF or HF sonar sources (narrower band). As described above, we
expect the majority of these takes to be in the form of mild (single-
digit), short-term (minutes to hours), narrower band (only affecting a
portion of the animal's hearing range) TTS. This means that for one to
several times per year, for several minutes to maybe a few hours (high
end) each, a taken individual will have slightly diminished hearing
sensitivity (slightly more than natural variation, but nowhere near
total deafness). More often than not, such an exposure would occur
within a narrower mid- to higher frequency band that may overlap part
(but not all) of a communication, echolocation, or predator range, but
sometimes across a lower or broader bandwidth. The significance of TTS
is also related to the auditory cues that are germane within the time
period that the animal incurs the TTS--for example, if an odontocete
has TTS at echolocation frequencies, but incurs it at night when it is
resting and not feeding, for example, it is not impactful. In short,
the expected results of any one of these small number of mild TTS
occurrences could be that (1) it does not overlap signals that are
pertinent to that animal in the given time period, (2) it overlaps
parts of signals that are important to the animal, but not in a manner
that impairs interpretation, or (3) it reduces detectability of an
important signal to a small degree for a short amount of time--in which
case the animal may be aware and be able to compensate (but there may
be slight energetic cost), or the animal may have some reduced
opportunities (e.g., to detect prey) or reduced capabilities to react
with maximum effectiveness (e.g., to detect a predator or navigate
optimally). However, given the small number of times that any
individual might incur TTS, the low degree of TTS and the short
anticipated duration, and the low likelihood that one of these
instances would occur in a time period in which the specific TTS
overlapped the entirety of a critical signal, it is unlikely that TTS
of the nature expected to result from the Navy activities would result
in behavioral changes or other impacts that would impact any
individual's (of any hearing sensitivity) reproduction or survival.
Auditory Masking or Communication Impairment
The ultimate potential impacts of masking on an individual (if it
were to occur) are similar to those discussed for TTS, but an important
difference is that masking only occurs during the time of the signal,
versus TTS, which continues beyond the duration of the signal.
Fundamentally, masking is referred to as a chronic effect because one
of the key harmful components of masking is its duration--the fact that
an animal would have reduced ability to hear or interpret critical cues
becomes much more likely to cause a problem the longer it is occurring.
Also inherent in the concept of masking is the fact that the potential
for the effect is only present during the times that the animal and the
source are in close enough proximity for the effect to occur (and
further, this time period would need to coincide with a time that the
animal was utilizing sounds at the masked frequency). As our analysis
has indicated, because of the relative movement of vessels and the
species involved in this rule, we do not expect the exposures with the
potential for masking to be of a long duration. In addition, masking is
fundamentally more of a concern at lower frequencies, because low
frequency signals propagate significantly further than higher
frequencies and because they are more likely to overlap both the
narrower LF calls of mysticetes, as well as many non-communication cues
such as fish and invertebrate prey, and geologic sounds that inform
navigation. It should be noted that the Navy is only proposing
authorization for a small subset of more narrow frequency LF sources
and for less than 11 hours cumulatively annually. Masking is also more
of a concern from continuous sources (versus intermittent sonar
signals) where there is no quiet time between pulses within which
auditory signals can be detected and interpreted. For these reasons,
dense aggregations of, and long exposure to, continuous LF activity are
much more of a concern for masking, whereas comparatively short-term
exposure to the predominantly intermittent pulses of often narrow
frequency range MFAS or HFAS, or explosions are not expected to result
in a meaningful amount of masking. While the Navy occasionally uses LF
and more continuous sources, it is not in the contemporaneous aggregate
amounts that would accrue to a masking concern. Specifically, the
nature of the activities and sound sources used by the Navy do not
support the likelihood of a level of masking accruing that would have
the potential to affect reproductive success or survival. Additional
detail is provided below.
Standard hull-mounted MFAS typically pings every 50 seconds. Some
hull-mounted anti-submarine sonars can also be used in an object
detection mode known as ``Kingfisher'' mode (e.g., used on vessels when
transiting to and from port) where pulse length is shorter but pings
are much closer together in both time and space since the vessel goes
slower when operating in this mode. For the majority of other sources,
the pulse length is significantly shorter than hull-mounted active
sonar, on the order of several microseconds to tens of milliseconds.
Some of the vocalizations that many marine mammals make are less than
one second long, so, for example with hull-mounted sonar, there would
be a 1 in 50 chance (only if the source was in close enough proximity
for the sound to exceed the signal that is being detected) that a
single vocalization might be masked by a ping. However, when
vocalizations (or series of vocalizations) are longer than one second,
masking would not occur. Additionally, when the pulses are only several
microseconds long, the majority of most animals' vocalizations would
not be masked.
Most ASW sonars and countermeasures use MF frequencies and a few
use LF and HF frequencies. Most of these sonar signals are limited in
the temporal, frequency, and spatial domains. The duration of most
individual sounds is short, lasting up to a few seconds each. A few
systems operate with higher duty cycles or
[[Page 5880]]
nearly continuously, but they typically use lower power, which means
that an animal would have to be closer, or in the vicinity for a longer
time, to be masked to the same degree as by a higher level source.
Nevertheless, masking could occasionally occur at closer ranges to
these high-duty cycle and continuous active sonar systems, but as
described previously, it would be expected to be of a short duration
when the source and animal are in close proximity. While data are
lacking on behavioral responses of marine mammals to continuously
active sonars, mysticete species are known to be able to habituate to
novel and continuous sounds (Nowacek et al., 2004), suggesting that
they are likely to have similar responses to high-duty cycle sonars.
Furthermore, most of these systems are hull-mounted on surface ships
and ships are moving at least 10 kn and it is unlikely that the ship
and the marine mammal would continue to move in the same direction and
it be subjected to the same exposure due to that movement. Most ASW
activities are geographically dispersed and last for only a few hours,
often with intermittent sonar use even within this period. Most ASW
sonars also have a narrow frequency band (typically less than one-third
octave). These factors reduce the likelihood of sources causing
significant masking. HF signals (above 10 kHz) attenuate more rapidly
in the water due to absorption than do lower frequency signals, thus
producing only a very small zone of potential masking. If masking or
communication impairment were to occur briefly, it would more likely be
in the frequency range of MFAS (the more powerful source), which
overlaps with some odontocete vocalizations (but few mysticete
vocalizations); however, it would likely not mask the entirety of any
particular vocalization, communication series, or other critical
auditory cue, because the signal length, frequency, and duty cycle of
the MFAS/HFAS signal does not perfectly resemble the characteristics of
any single marine mammal species' vocalizations.
Other sources used in Navy training and testing that are not
explicitly addressed above, many of either higher frequencies (meaning
that the sounds generated attenuate even closer to the source) or lower
amounts of operation, are similarly not expected to result in masking.
For the reasons described here, any limited masking that could
potentially occur would be minor and short-term.
In conclusion, masking is more likely to occur in the presence of
broadband, relatively continuous noise sources such as from vessels,
however, the duration of temporal and spatial overlap with any
individual animal and the spatially separated sources that the Navy
uses would not be expected to result in more than short-term, low
impact masking that would not affect reproduction or survival.
PTS From Sonar Acoustic Sources and Explosives and Tissue Damage From
Explosives
Tables 51 through 55 indicate the number of individuals of each
species for which Level A harassment in the form of PTS resulting from
exposure to active sonar and/or explosives is estimated to occur. The
number of individuals to potentially incur PTS annually (from sonar and
explosives) for each species ranges from 0 to 50 (50 is for Dwarf sperm
whale), but is more typically 0 or 1. No species have the potential to
incur tissue damage from explosives.
Data suggest that many marine mammals would deliberately avoid
exposing themselves to the received levels of active sonar necessary to
induce injury by moving away from or at least modifying their path to
avoid a close approach. Additionally, in the unlikely event that an
animal approaches the sonar-emitting vessel at a close distance, NMFS
has determined that the mitigation measures (i.e., shutdown/powerdown
zones for active sonar) would typically ensure that animals would not
be exposed to injurious levels of sound. As discussed previously, the
Navy utilizes both aerial (when available) and passive acoustic
monitoring (during ASW exercises, passive acoustic detections are used
as a cue for Lookouts' visual observations when passive acoustic assets
are already participating in an activity) in addition to Lookouts on
vessels to detect marine mammals for mitigation implementation. As
discussed previously, the Navy utilized a post-modeling quantitative
assessment to adjust the take estimates based on avoidance and the
likely success of some portion of the mitigation measures. As is
typical in predicting biological responses, it is challenging to
predict exactly how avoidance and mitigation will affect the take of
marine mammals, and therefore the Navy erred on the side of caution in
choosing a method that would more likely still overestimate the take by
PTS to some degree. Nonetheless, these modified Level A harassment take
numbers represent the maximum number of instances in which marine
mammals would be reasonably expected to incur PTS, and we have analyzed
them accordingly.
If a marine mammal is able to approach a surface vessel within the
distance necessary to incur PTS in spite of the mitigation measures,
the likely speed of the vessel (nominally 10-15 kn) and relative motion
of the vessel would make it very difficult for the animal to remain in
range long enough to accumulate enough energy to result in more than a
mild case of PTS. As discussed previously in relation to TTS, the
likely consequences to the health of an individual that incurs PTS can
range from mild to more serious dependent upon the degree of PTS and
the frequency band it is in. The majority of any PTS incurred as a
result of exposure to Navy sources would be expected to be in the 2-20
kHz range (resulting from the most powerful hull-mounted sonar) and
could overlap a small portion of the communication frequency range of
many odontocetes, whereas other marine mammal groups have communication
calls at lower frequencies. Regardless of the frequency band though,
the more important point in this case is that any PTS accrued as a
result of exposure to Navy activities would be expected to be of a
small amount (single digits). Permanent loss of some degree of hearing
is a normal occurrence for older animals, and many animals are able to
compensate for the shift, both in old age or at younger ages as the
result of stressor exposure. While a small loss of hearing sensitivity
may include some degree of energetic costs for compensating or may mean
some small loss of opportunities or detection capabilities, at the
expected scale it would be unlikely to impact behaviors, opportunities,
or detection capabilities to a degree that would interfere with
reproductive success or survival.
The Navy implements mitigation measures (described in the Proposed
Mitigation Measures section) during explosive activities, including
delaying detonations when a marine mammal is observed in the mitigation
zone. Nearly all explosive events would occur during daylight hours to
improve the sightability of marine mammals and thereby improve
mitigation effectiveness. Observing for marine mammals during the
explosive activities would include visual and passive acoustic
detection methods (when they are available and part of the activity)
before the activity begins, in order to cover the mitigation zones that
can range from 200 yds (183 m) to 2,500 yds (2,286 m) depending on the
source (e.g., explosive sonobuoy, explosive torpedo, explosive bombs),
and 2.5 NM for sinking exercise (see Tables 36-44). For
[[Page 5881]]
all of these reasons, the proposed mitigation measures associated with
explosives are expected to be effective in preventing tissue damage to
any potentially affected species, and no species are anticipated to
incur tissue damage during the period of the proposed rule.
Group and Species-Specific Analyses
The maximum amount and type of incidental take of marine mammals
reasonably likely to occur from exposure to sonar and other active
acoustic sources and explosions and therefore proposed to be authorized
during the seven-year training and testing period are shown in Table
30. The vast majority of predicted exposures (greater than 99 percent)
are expected to be Level B harassment (TTS and behavioral reactions)
from acoustic and explosive sources during training and testing
activities at relatively low received levels.
In the discussions below, the estimated Level B harassment takes
represent instances of take, not the number of individuals taken (the
much lower and less frequent Level A harassment takes are far more
likely to be associated with separate individuals), and in some cases
individuals may be taken more than one time. Below, we compare the
total take numbers (including PTS, TTS, and behavioral disruption) for
species to their associated abundance estimates to evaluate the
magnitude of impacts across the species and to individuals.
Specifically, when an abundance percentage comparison is below 100, it
means that that percentage or less of the individuals will be affected
(i.e., some individuals will not be taken at all), that the average for
those taken is one day per year, and that we would not expect any
individuals to be taken more than a few times in a year.
To assist in understanding what this analysis means, we clarify a
few issues related to estimated takes and the analysis here. An
individual that incurs a PTS or TTS take may sometimes, for example,
also be subject to behavioral disturbance at the same time. As
described above in this section, the degree of PTS, and the degree and
duration of TTS, expected to be incurred from the Navy's activities are
not expected to impact marine mammals such that their reproduction or
survival could be affected. Similarly, data do not suggest that a
single instance in which an animal accrues PTS or TTS and is subject to
behavioral disturbance would result in impacts to reproduction or
survival. Alternately, we recognize that if an individual is subjected
to behavioral disturbance repeatedly for a longer duration and on
consecutive days, effects could accrue to the point that reproductive
success is jeopardized, although those sorts of impacts are not
expected to result from these activities. Accordingly, in analyzing the
number of takes and the likelihood of repeated and sequential takes, we
consider the total takes, not just the Level B harassment takes by
behavioral disruption, so that individuals potentially exposed to both
threshold shift and behavioral disruption are appropriately considered.
The number of Level A harassment takes by PTS are so low (and zero in
most cases) compared to abundance numbers that it is considered highly
unlikely that any individual would be taken at those levels more than
once.
Use of sonar and other transducers would typically be transient and
temporary. The majority of acoustic effects to mysticetes from sonar
and other active sound sources during testing and training activities
would be primarily from ASW events. It is important to note that
although ASW is one of the warfare areas of focus during MTEs, there
are significant periods when active ASW sonars are not in use.
Nevertheless, behavioral reactions are assumed more likely to be
significant during MTEs than during other ASW activities due to the
duration (i.e., multiple days) and scale (i.e., multiple sonar
platforms) of the MTEs. On the less severe end, exposure to
comparatively lower levels of sound at a detectably greater distance
from the animal, for a few or several minutes, could result in a
behavioral response such as avoiding an area that an animal would
otherwise have moved through or fed in, or breaking off one or a few
feeding bouts. More severe behavioral effects could occur when an
animal gets close enough to the source to receive a comparatively
higher level of sound, is exposed continuously to one source for a
longer time, or is exposed intermittently to different sources
throughout a day. Such effects might result in an animal having a more
severe flight response and leaving a larger area for a day or more, or
potentially losing feeding opportunities for a day. However, such
severe behavioral effects are expected to occur infrequently.
Occasional, milder behavioral reactions are unlikely to cause long-
term consequences for individual animals or populations, and even if
some smaller subset of the takes are in the form of a longer (several
hours or a day) and more severe responses, if they are not expected to
be repeated over sequential days, impacts to individual fitness are not
anticipated. Nearly all studies and experts agree that infrequent
exposures of a single day or less are unlikely to impact an
individual's overall energy budget (Farmer et al., 2018; Harris et al.,
2017; King et al., 2015; NAS 2017; New et al., 2014; Southall et al.,
2007; Villegas-Amtmann et al., 2015).
The analyses below in some cases address species collectively if
they occupy the same functional hearing group (i.e., low, mid, and
high-frequency cetaceans), share similar life history strategies, and/
or are known to behaviorally respond similarly to acoustic stressors.
Because some of these groups or species share characteristics that
inform the impact analysis similarly, it would be duplicative to repeat
the same analysis for each species. In addition, similar species
typically have the same hearing capabilities and behaviorally respond
in the same manner.
Thus, our analysis below considers the effects of the Navy's
activities on each affected species even where discussion is organized
by functional hearing group and/or information is evaluated at the
group level. Where there are meaningful differences between a species
that would further differentiate the analysis, they are either
described within the section or the discussion for those species is
included as a separate subsection. Specifically below, we first give
broad descriptions of the mysticete and odontocete groups and then
differentiate into further groups and species as appropriate.
Mysticetes
This section builds on the broader discussion above and brings
together the discussion of the different types and amounts of take that
different species will incur, the applicable mitigation for species,
and the status of the species to support the negligible impact
determinations. We have described (above in this section) the
unlikelihood of any masking having effects that would impact the
reproduction or survival of any of the individual marine mammals
affected by the Navy's activities. For mysticetes, there is no
predicted PTS from sonar or explosives and no predicted tissue damage
from explosives for any species. Much of the discussion below focuses
on the behavioral effects and the mitigation measures that reduce the
probability or severity of effects. Because there are species-specific
factors in relation to the status of the species, at the end of the
section we break out our findings on a species-specific basis.
In Table 51 below for mysticetes, we indicate for each species the
Level A
[[Page 5882]]
and Level B harassment numbers, and a number indicating the instances
of total take as a percentage of abundance in the MITT Study Area
alone, as well as the MITT Study Area plus the transit corridor, which
was calculated separately. While the density used to calculate take is
the same for these two areas, the takes were calculated separately for
the two areas for all species in this proposed rule, not just
mysticetes, because the activity levels are higher in the MITT Study
Area and it is helpful to understand the comparative impacts in the two
areas.
Table 51--Annual Estimated Takes by Level B Harassment and Level A Harassment for Mysticetes and Number Indicating the Instances of Total Take as a
Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Instances of indicated types of incidental take (not all takes Abundance Instances of total take
represent separate individuals, especially for disturbance) -------------------------- as percentage of
----------------------------------------------------------------- abundance
Level B harassment Level A Total takes -------------------------
Species -------------------------- harassment -------------------------- MITT study
------------- MITT study MITT study area + MITT study
Behavioral MITT study area + area transit MITT study area +
disturbance TTS PTS area transit corridor area transit
corridor corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale......................... 4 20 0 24 24 179 200 13 12
Bryde's whale...................... 40 258 0 296 297 1,470 1,595 20 19
Fin whale.......................... 5 20 0 25 25 215 240 12 10
Humpback whale..................... 57 422 0 476 479 3,190 3,563 15 13
Minke whale........................ 10 85 0 95 95 538 601 18 16
Omura's whale...................... 4 25 0 28 28 143 160 20 18
Sei whale.......................... 19 136 0 154 155 1,040 1,094 15 14
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
Estimated Take of Marine Mammals section.
The majority of takes by harassment of mysticetes in the MITT Study
Area are caused by sources from the MF1 active sonar bin (which
includes hull-mounted sonar) because they are high level, narrowband
sources in the 1-10 kHz range, which intersect what is estimated to be
the most sensitive area of hearing for mysticetes. They also are used
in a large portion of exercises (see Table 1.5-1 in the Navy's
application). Most of the takes (66 percent) from the MF1 bin in the
MITT Study Area would result from received levels between 154 and 172
dB SPL, while another 33 percent would result from exposure between 172
and 178 dB SPL. For the remaining active sonar bin types, the
percentages are as follows: LF4 = 97 percent between 124 and 136 dB
SPL, MF4 = 99 percent between 136 and 154 dB SPL, MF5 = 98 percent
between 118 and 142 dB SPL, and HF4 = 98 percent between 100 and 148 dB
SPL. These values may be derived from the information in Tables 6.4-8
through 6.4-12 in the Navy's rulemaking/LOA application (though they
were provided directly to NMFS upon request). No blue whales or fin
whales will be taken by Level B harassment or PTS as a result of
exposure to explosives. For other mysticetes, exposure to explosives
will result in small numbers of take: 1-6 Level B behavioral harassment
takes per species, 0-3 TTS takes per species (0 for sei whales), and 0
PTS takes.
Research and observations show that if mysticetes are exposed to
sonar or other active acoustic sources they may react in a number of
ways depending on the characteristics of the sound source, their
experience with the sound source, and whether they are migrating or on
seasonal feeding or breeding grounds. Behavioral reactions may include
alerting, breaking off feeding dives and surfacing, diving or swimming
away, or no response at all (DOD, 2017; Nowacek, 2007; Richardson,
1995; Southall et al., 2007). Overall, mysticetes have been observed to
be more reactive to acoustic disturbance when a noise source is located
directly on their migration route. Mysticetes disturbed while migrating
could pause their migration or route around the disturbance, while
males en route to breeding grounds have been shown to be less
responsive to disturbances. Although some may pause temporarily, they
will resume migration shortly after the exposure ends. Animals
disturbed while engaged in other activities such as feeding or
reproductive behaviors may be more likely to ignore or tolerate the
disturbance and continue their natural behavior patterns. Alternately,
adult females with calves may be more responsive to stressors. As noted
in the Potential Effects of Specified Activities on Marine Mammals and
Their Habitat section, there are multiple examples from behavioral
response studies of odontocetes ceasing their feeding dives when
exposed to sonar pulses at certain levels, but alternately, blue whales
were less likely to show a visible response to sonar exposures at
certain levels when feeding than when traveling. However, Goldbogen et
al. (2013) indicated some horizontal displacement of deep foraging blue
whales in response to simulated MFA sonar. Most Level B behavioral
harassment of mysticetes is likely to be short-term and of low to
sometimes moderate severity, with no anticipated effect on reproduction
or survival from Level B harassment.
Richardson et al. (1995) noted that avoidance (temporary
displacement of an individual from an area) reactions are the most
obvious manifestations of disturbance in marine mammals. Avoidance is
qualitatively different from the startle or flight response, but also
differs in the magnitude of the response (i.e., directed movement, rate
of travel, etc.). Oftentimes avoidance is temporary, and animals return
to the area once the noise has ceased. Some mysticetes may avoid larger
activities such as a MTE as it moves through an area, although these
activities do not typically use the same training locations day-after-
day during multi-day activities, except periodically in instrumented
ranges. Therefore, displaced animals could return quickly after the MTE
finishes. Due to the limited number and geographic scope of MTEs, it is
unlikely that most mysticetes would encounter an MTE more than once per
year and additionally, total hull-mounted sonar hours would be limited
in several areas that are important to mysticetes (described below). In
the ocean, the use of Navy sonar and other active acoustic sources is
transient and is unlikely to expose the same population of animals
repeatedly over a short period of time, especially given the broader-
scale movements of mysticetes.
The implementation of procedural mitigation and the sightability of
[[Page 5883]]
mysticetes (due to their large size) further reduces the potential for
a significant behavioral reaction or a threshold shift to occur (i.e.,
shutdowns are expected to be successfully implemented), which is
reflected in the amount and type of incidental take that is anticipated
to occur and proposed to be authorized.
As noted previously, when an animal incurs a threshold shift, it
occurs in the frequency from that of the source up to one octave above.
This means that the vast majority of threshold shifts caused by Navy
sonar sources will typically occur in the range of 2-20 kHz (from the
1-10 kHz MF1 bin, though in a specific narrow band within this range as
the sources are narrowband), and if resulting from hull-mounted sonar,
will be in the range of 3.5-7 kHz. The majority of mysticete
vocalizations occur in frequencies below 1 kHz, which means that TTS
incurred by mysticetes will not interfere with conspecific
communication. Additionally, many of the other critical sounds that
serve as cues for navigation and prey (e.g., waves, fish,
invertebrates) occur below a few kHz, which means that detection of
these signals will not be inhibited by most threshold shift either.
When we look in ocean areas where the Navy has been intensively
training and testing with sonar and other active acoustic sources for
decades, there is no data suggesting any long-term consequences to
reproduction or survival rates of mysticetes from exposure to sonar and
other active acoustic sources.
All the species discussed in this section would benefit from the
procedural mitigation measures described earlier in the Proposed
Mitigation Measures section. In addition, the Navy would limit
activities and employ other measures in mitigation areas that would
avoid or reduce impacts to mysticetes. The Navy would implement time/
area mitigation for explosives for humpback whales in the Marpi and
Chalan Kanoa Reef Geographic Mitigation Areas as by prohibiting
explosives year-round. The Navy would also implement the Marpi and
Chalan Kona Reef Awareness Notification Message Areas that would avoid
interactions with large whales that may be vulnerable to vessel
strikes. This is especially important for humpback whales that are
concentrated in these areas for breeding and calving.
Below we compile and summarize the information that supports our
preliminary determination that the Navy's activities would not
adversely affect any species through effects on annual rates of
recruitment or survival for any of the affected mysticete species.
Humpback whale-- Effective as of October 11, 2016, NMFS changed the
status of all humpback whales from an endangered species to a specific
status for each of the 14 identified distinct population segments
(DPSs) (81 FR 62259). The humpback whales in the MITT Study Area are
indirectly addressed in the Alaska SAR, given that the historic range
of humpbacks in the ``Asia wintering area'' includes the Mariana
Islands. The observed presence of humpback whales in the Mariana
Islands (Hill et al., 2016a; Hill et al., 2017a; Hill et al., 2018;
Klinck et al., 2016a; Munger et al., 2014; NMFS, 2018; Oleson et al.,
2015; Uyeyama, 2014) are consistent with the MITT Study Area as a
plausible migratory destination for humpback whales from Alaska (Muto
et al., 2017a). It is likely that humpback whales in the Mariana
Islands are part of the endangered Western North Pacific DPS (WNP DPS)
based on the best available science (Bettridge et al., 2015;
Calambokidis et al., 2008; Calambokidis et al., 2010; Carretta et al.,
2017b; Hill et al., 2017b; Muto et al., 2017a; NMFS, 2016a; NOAA,
2015b; Wade et al., 2016) although the breeding range of the WNP DPS is
not fully resolved. Individual photo-identification data for whales
sampled off Saipan within the Mariana Archipelago in February-March
2015 to 2018, suggest that these whales belong to the WNP DPS (Hill et
al., in review). Specifically, comparisons with existing WNP humpback
whale photo-identification catalogs showed that 11 of 41 (27 percent)
whales within the Mariana Archipelago humpback whale catalog were
previously sighted in WNP breeding areas (Japan and Philippines) and/or
in a WNP feeding area off Russia (Hill et al., in review). No ESA
designated critical habitat has been proposed for the WNP DPS in the
MITT Study Area, although critical habitat has been proposed in Alaska
(84 FR 54534; October 9, 2019). There are no designated biologically
important areas; however, it is known that the areas of Marpi and
Chalan Kanoa Reefs (out to the 400 m isobath) are being specifically
used by mother/calf pairs of humpback whales (Hill et al., 2016, 2017,
2018, in-press). Currently, no other areas have been identified for
mother/calf pairs of humpback whales in the Mariana Islands.
The shallower water (less than 400 m) surrounding the Chalan Kanoa
Reef and Marpi Reef Geographic Mitigation Areas have not been a high-
use area for Navy MTEs and ASW training events as the area is
considered generally unsuitable for training needs. These areas
encompass water depths less than 400 m, with significant parts of the
mitigation areas less than 200 m. The distance between 400 and 200 m
isobaths is very small (between 0.5 and 2 nm). Most humpback whale
sightings in or near the mitigation areas were within the 200 m
isobath. The Navy typically conducts ASW that would also include the
use of surface ship hull-mounted sonar such as MF1 in water depths
greater than 200 m. Small scale and unit level ASW training is not
conducted within 3 nm of land (e.g., Small Joint Coordinated ASW
exercise, Tracking Exercise-surface ship). MTEs almost always use
established range subareas far offshore and well outside of 3 nm of
land. Close to half of the Chalan Kanoa Reef Geographic Mitigation Area
is 3 nm from land making this area less suitable to current Navy ASW
training needs. In addition, portions of the Chalan Kanoa Reef area
have established anchorages and presence of anchored vessels is not
conducive for ASW training with MF1 MFAS. Similarly, water depths less
than 200 m at Marpi Reef are also typically unsuited for current ASW
training needs, especially for group events. As part of proposed
mitigation, the Navy would not use explosives in these two Geographic
Mitigation Areas. Reducing exposure of humpback whales to explosive
detonations in these areas and at this time is expected to reduce the
likelihood of impacts that could affect reproduction or survival, by
minimizing impacts on calves during this sensitive life stage, avoiding
the additional energetic costs to mothers of avoiding the area during
explosive exercises, and minimizing the chances that important breeding
behaviors are interrupted to the point that reproduction is inhibited
or abandoned for the year, or otherwise interfered with.
Regarding the magnitude of Level B harassment takes (TTS and
behavioral disruption), the number of estimated total instances of take
compared to the abundance (measured against both the MITT Study Area
abundance and the MITT Study Area plus the transit corridor combined)
is 15 and 13 percent, respectively (Table 51). Regarding the severity
of those individual takes by Level B behavioral harassment, we have
explained that the duration of any exposure is expected to be between
minutes and hours (i.e., relatively short) and the received sound
levels largely below 172 dB with a portion up to 178 dB (i.e., of a
moderate or lower level, less likely to evoke a severe response).
Regarding the severity of TTS takes, they are expected to be
[[Page 5884]]
low-level, of short duration, and mostly not in a frequency band that
would be expected to interfere with communication or other important
low-frequency cues. Therefore the associated lost opportunities and
capabilities are not at a level that would impact reproduction or
survival.
Given the general lack of suitability of the shallow waters of
Marpi and Chalan Kanoa Reefs for Navy's activities, it is predicated
that only a small portion of individuals would be taken and disturbed
at a low-moderate level, with those individuals disturbed only once.
There is no expected Level A harassment. This low magnitude and
severity of harassment effects is not expected to result in impacts on
the reproduction or survival of any individuals and, therefore, the
total take is not expected to adversely affect this species through
impacts on annual rates of recruitment or survival. No mortality or
tissue damage is anticipated or proposed to be authorized. For these
reasons, we have determined, in consideration of all of the effects of
the Navy's activities combined, that the proposed authorized take would
have a negligible impact on humpback whales.
Blue whale--Blue whales are listed as endangered under the ESA
throughout their range, but there is no ESA designated critical habitat
or biologically important areas identified for this species in the MITT
Study Area. There are no recent sighting records for blue whales in the
MITT Study Area (Fulling et al., 2011; Hill et al., 2017a; Uyeyama,
2014). Some acoustic detections from passive monitoring devices
deployed at Saipan and Tinian have recorded the presence of blue whales
over short periods of time (a few days) (Oleson et al., 2015). However,
since blue whale calls can travel very long distances (up to 621 mi
(1,000 km)), it is unknown whether the animals were within the MITT
Study Area. Blue whales would be most likely to occur in the MITT Study
Area during the winter and are expected to be few in number.
Regarding the magnitude of Level B harassment takes (TTS and
behavioral disruption), the number of estimated total instances of take
compared to the abundance (measured against both the MITT Study Area
abundance and the MITT Study Area plus the transit corridor combined)
is 13 and 12 percent, respectively (Table 51). Regarding the severity
of those individual takes by Level B behavioral harassment, we have
explained that the duration of any exposure is expected to be between
minutes and hours (i.e., relatively short) and the received sound
levels largely below 172 dB with a portion up to 178 dB (i.e., of a
moderate or lower level, less likely to evoke a severe response).
Regarding the severity of TTS takes, they are expected to be low-level,
of short duration, and mostly not in a frequency band that would be
expected to interfere with communication or other important low-
frequency cues. Therefore the associated lost opportunities and
capabilities are not at a level that would impact reproduction or
survival.
Given the range of blue whales and the low abundance in the MITT
Study Area, this information suggests that a very small portion of
individuals would be taken and disturbed at a low-moderate level, with
those individuals disturbed only once. There is no expected Level A
harassment. This low magnitude and severity of harassment effects is
not expected to result in impacts on the reproduction or survival of
any individuals and, therefore, the total take is not expected to
adversely affect this species through impacts on annual rates of
recruitment or survival. No mortality or tissue damage is anticipated
or proposed to be authorized. For these reasons, we have determined, in
consideration of all of the effects of the Navy's activities combined,
that the proposed authorized take would have a negligible impact on
blue whales.
Fin whale--Fin whales are listed as endangered under the ESA
throughout their range, but there is no ESA designated critical habitat
or biologically important areas identified for this species in the MITT
Study Area. There are no sighting records for fin whales in the MITT
Study Area (Fulling et al., 2011; Hill et al., 2017a; Oleson et al.,
2015; Uyeyama, 2014). Based on acoustic detections, fin whales are
expected to be present in the MITT Study Area although few in number.
Acoustic detections from passive monitoring devices deployed at Saipan
and Tinian have recorded the presence of fin whales over short (a few
days) periods of time (Oleson et al., 2015), and fin whale
vocalizations were detected in January 2010 in the Transit Corridor
between Hawaii and Guam (Oleson and Hill, 2010a). Regarding the
magnitude of Level B harassment takes (TTS and behavioral disruption),
the number of estimated total instances of take compared to the
abundance (measured against both the MITT Study Area abundance and the
MITT Study Area plus the transit corridor combined) is 12 and 10
percent, respectively (Table 51). Regarding the severity of those
individual takes by Level B behavioral harassment, we have explained
that the duration of any exposure is expected to be between minutes and
hours (i.e., relatively short) and the received sound levels largely
below 172 dB with a portion up to 178 dB (i.e., of a moderate or lower
level, less likely to evoke a severe response). Regarding the severity
of TTS takes, they are expected to be low-level, of short duration, and
mostly not in a frequency band that would be expected to interfere with
communication or other important low-frequency cues. Therefore, the
associated lost opportunities and capabilities are not at a level that
would impact reproduction or survival.
Given the low abundance of fin whales in the MITT Study Area, this
information suggests that a very small portion of individuals would be
taken and disturbed at a low-moderate level, with those individuals
disturbed only once. There is no expected Level A harassment. This low
magnitude and severity of harassment effects is not expected to result
in impacts on the reproduction or survival of any individuals and,
therefore, the total take is not expected to adversely affect this
species through impacts on annual rates of recruitment or survival. No
mortality or tissue damage is anticipated or proposed to be authorized.
For these reasons, we have determined, in consideration of all of the
effects of the Navy's activities combined, that the proposed authorized
take would have a negligible impact on fin whales.
Sei whale--Sei whales are listed as endangered under the ESA
throughout their range, but there is no ESA designated critical habitat
or biologically important areas identified for this species in the MITT
Study Area. In the 2007 survey of the Mariana Islands (Fulling et al.,
2011), a total of 16 sei whales were sighted in coverage of
approximately 24 percent of the MITT Study Area. Sei whales were also
visually detected in the Transit Corridor between the MITT Study Area
and Hawaii during a NMFS survey in January 2010 (Oleson and Hill,
2010a). Regarding the magnitude of Level B harassment takes (TTS and
behavioral disruption), the number of estimated total instances of take
compared to the abundance (measured against both the MITT Study Area
abundance and the MITT Study Area plus the transit corridor combined)
is 15 and 14 percent, respectively (Table 51). Regarding the severity
of those individual takes by Level B behavioral harassment, we have
explained that the duration of any exposure is expected to be between
minutes and hours (i.e., relatively short) and the received sound
levels largely below 172 dB with a
[[Page 5885]]
portion up to 178 dB (i.e., of a moderate or lower level, less likely
to evoke a severe response). Regarding the severity of TTS takes, they
are expected to be low-level, of short duration, and mostly not in a
frequency band that would be expected to interfere with communication
or other important low-frequency cues. Therefore the associated lost
opportunities and capabilities are not at a level that would impact
reproduction or survival.
Given the low occurrence of sei whales in the MITT Study Area, this
information suggests that a very small portion of individuals would be
taken and disturbed at a low-moderate level, with those individuals
disturbed only once. There is no expected Level A harassment. This low
magnitude and severity of harassment effects is not expected to result
in impacts on the reproduction or survival of any individuals and,
therefore, the total take is not expected to adversely affect this
species through impacts on annual rates of recruitment or survival. No
mortality or tissue damage is anticipated or proposed to be authorized.
For these reasons, we have determined, in consideration of all of the
effects of the Navy's activities combined, that the proposed authorized
take would have a negligible impact on sei whales.
Bryde's whale, Minke whale, Omura's whale--These whales are not
listed as endangered or threatened under the ESA. Bryde's whale are
expected to be present in the MITT Study Area based on sighting records
(Fulling et al., 2011; Hill et al., 2017a; Mobley, 2007; Oleson and
Hill, 2010a; Uyeyama, 2014). Bryde's whales were detected in the
Transit Corridor between the MITT Study Area and Hawaii during a NMFS
survey in January 2010 (Oleson and Hill, 2010a). Bryde's whales were
also encountered off Rota during a small boat non-systematic survey in
August-September 2015 (Hill et al., 2017a). Minke whales have not been
visually detected in the MITT Study Area during any known survey
efforts within approximately the last decade (Fulling et al., 2011;
Hill et al., 2011; Hill et al., 2013; Hill et al., 2014; Hill et al.,
2015; Hill et al., 2017a; Mobley, 2007; Oleson and Hill, 2010a; Tetra
Tech Inc., 2014; Uyeyama, 2014). However, acoustic data collected
during line-transect surveys did detect calling minke whales (Norris et
al., 2017). Omura's whale is thought to be present in the MITT Study
Area, but no data is available to estimate abundance.
Regarding the magnitude of Level B harassment takes (TTS and
behavioral disruption), the number of estimated total instances of take
compared to the abundance (measured against both the MITT Study Area
abundance and the MITT Study Area plus the transit corridor combined)
is 18-20 and 16-19 percent, respectively (Table 51). Regarding the
severity of those individual takes by Level B behavioral harassment, we
have explained that the duration of any exposure is expected to be
between minutes and hours (i.e., relatively short) and the received
sound levels largely below 172 dB with a portion up to 178 dB (i.e., of
a moderate or lower level, less likely to evoke a severe response).
Regarding the severity of TTS takes, they are expected to be low-level,
of short duration, and mostly not in a frequency band that would be
expected to interfere with communication or other important low-
frequency cues. Therefore the associated lost opportunities and
capabilities are not at a level that would impact reproduction or
survival.
Given the low occurrence of Bryde's whales and minke whales and the
low abundance of Omura's whales in the MITT Study Area, this
information suggests that a small portion of individuals would be taken
and disturbed at a low-moderate level, with those individuals disturbed
only once. There is no expected Level A harassment. This low magnitude
and severity of harassment effects is not expected to result in impacts
on the reproduction or survival of any individuals and, therefore, the
total take is not expected to adversely affect these species through
impacts on annual rates of recruitment or survival. No mortality or
tissue damage is anticipated or proposed to be authorized. For these
reasons, we have determined, in consideration of all of the effects of
the Navy's activities combined, that the proposed authorized take would
have a negligible impact on Bryde's whales, minke whales, and Omura's
whales.
Altogether, no mortality or Level A harassment is anticipated or
proposed to be authorized. Regarding the magnitude of Level B
harassment takes (TTS and behavioral disruption), the number of
estimated total instances of take compared to the abundance is 20
percent or less for all mysticetes in the MITT Study Area and 19
percent or less in the MITT Study Area and transit corridor combined
(Table 51). Regarding the severity of those individual Level B
harassment takes by behavioral disruption, the duration of any exposure
is expected to be between minutes and hours (i.e., relatively short)
and the received sound levels largely below 172 dB with a portion up to
178 dB (i.e., of a moderate or lower level, less likely to evoke a
severe response). Regarding the severity of TTS takes, they are
expected to be low-level, of short duration, and mostly not in a
frequency band that would be expected to interfere with communication
or other important low-frequency cues. Therefore, the associated lost
opportunities and capabilities are not at a level that would impact
reproduction or survival.
Only a small portion of any mysticete population is anticipated to
be impacted, and any individual whale is likely to be disturbed at a
low-moderate level, with the taken individuals likely exposed on one
day or perhaps over a few days for a small number of individuals, with
little chance that any are taken across sequential days. This low
magnitude and severity of harassment effects is unlikely to result in
impacts on individual reproduction or survival, much less annual rates
of recruitment or survival of any of the species. For these reasons, we
have preliminarily determined, in consideration of all of the effects
of the Navy's activities combined, that the proposed authorized take
would have a negligible impact on all of the mysticete species.
Odontocetes
This section builds on the broader discussion above and brings
together the discussion of the different types and amounts of take that
different species would incur, the applicable mitigation for each
species, and the status of the species to support the negligible impact
determinations for each species. We have previously described the
unlikelihood of any masking or habitat impacts having effects that
would impact the reproduction or survival of any of the individual
marine mammals affected by the Navy's activities. Here, we include
information that applies to all of the odontocete species, which are
then further divided and discussed in more detail in the following
subsections: Dwarf sperm whales and pygmy sperm whales; sperm whales;
beaked whales; and dolphins and small whales. These subsections include
more specific information about the groups, as well as conclusions for
each species represented.
The majority of takes by harassment of odontocetes in the MITT
Study Area are caused by sources from the MF1 active sonar bin (which
includes hull-mounted sonar) because they are high level, typically
narrowband sources at a frequency (in the 1-10 kHz range) that overlaps
a more sensitive portion (though not the most sensitive) of the MF
hearing range and they are used in a large portion of exercises (see
Table 1.5-1 in the Navy's rulemaking/LOA
[[Page 5886]]
application). For odontocetes other than beaked whales (for which these
percentages are indicated separately in that section), most of the
takes (98 percent) from the MF1 bin in the MITT Study Area would result
from received levels between 154 and 172 dB SPL. For the remaining
active sonar bin types, the percentages are as follows: LF4 = 97
percent between 124 and 136 dB SPL, MF4 = 99 percent between 136 and
160 dB SPL, MF5 = 97 percent between 118 and 142 dB SPL, and HF4 = 88.6
percent between 100 and 130 dB SPL. These values may be derived from
the information in Tables 6.4-8 through 6.4-12 in the Navy's
rulemaking/LOA application (though they were provided directly to NMFS
upon request). Based on this information, the majority of the takes by
Level B behavioral harassment are expected to be low to sometimes
moderate in nature, but still of a generally shorter duration.
For all odontocetes, takes from explosives (Level B behavioral
harassment, TTS, or PTS) comprise a very small fraction (and low
number) of those caused by exposure to active sonar. For the following
odontocetes, zero takes from explosives are expected to occur:
Blainville's beaked whales, Cuvier's beaked whales, bottlenose
dolphins, false killer whales, killer whales, spinner dolphins, sperm
whales, rough-toothed dolphins, and pygmy killer whale. For Level B
behavioral disruption from explosives, 1 to 4 takes are expected to
occur for all but three of the remaining odontocetes, 0 takes for
spinner dolphins, and 25 and 64 takes for pygmy and dwarf sperm whales,
respectively. The instances of PTS expected to occur from explosives
are 0-1 per species and instances of TTS expected to occur from
explosives are 0-5 per species, except for pygmy and dwarf sperm
whales. Because of the lower PTS threshold for HF species, pygmy and
dwarf sperm whales are expected to have 25 and 64 Level B behavioral
harassment takes, 8 and 21 PTS takes, and 37 and 100 TTS takes from
explosives, respectively.
Because the majority of harassment takes of odontocetes result from
the sources in the MF1 bin, the vast majority of threshold shift would
occur at a single frequency within the 1-10 kHz range and, therefore,
the vast majority of threshold shift caused by Navy sonar sources would
be at a single frequency within the range of 2-20 kHz. The frequency
range within which any of the anticipated narrowband threshold shift
would occur would fall directly within the range of most odontocete
vocalizations (2-20kHz). For example, the most commonly used hull-
mounted sonar has a frequency around 3.5 kHz, and any associated
threshold shift would be expected to be at around 7 kHz. However,
odontocete vocalizations typically span a much wider range than this,
and alternately, threshold shift from active sonar will often be in a
narrower band (reflecting the narrower band source that caused it),
which means that TTS incurred by odontocetes would typically only
interfere with communication within a portion of their range (if it
occurred during a time when communication with conspecifics was
occurring) and, as discussed earlier, it would only be expected to be
of a short duration and relatively small degree. Odontocete
echolocation occurs predominantly at frequencies significantly higher
than 20 kHz, though there may be some small overlap at the lower part
of their echolocating range for some species, which means that there is
little likelihood that threshold shift, either temporary or permanent
would interfere with feeding behaviors. Many of the other critical
sounds that serve as cues for navigation and prey (e.g., waves, fish,
invertebrates) occur below a few kHz, which means that detection of
these signals will not be inhibited by most threshold shift either. The
low number of takes by threshold shift that might be incurred by
individuals exposed to explosives would likely be lower frequency (5
kHz or less) and spanning a wider frequency range, which could slightly
lower an individual's sensitivity to navigational or prey cues, or a
small portion of communication calls, for several minutes to hours (if
temporary) or permanently. There is no reason to think that any of the
individual odontocetes taken by TTS would incur these types of takes
over more than one day, or over a few days at most, and therefore they
are unlikely to incur impacts on reproduction or survival. PTS takes
from these sources are very low, and while spanning a wider frequency
band, are still expected to be of a low degree (i.e., low amount of
hearing sensitivity loss) and unlikely to affect reproduction or
survival.
The range of potential behavioral effects of sound exposure on
marine mammals generally, and odontocetes specifically, has been
discussed in detail previously. There are behavioral patterns that
differentiate the likely impacts on odontocetes as compared to
mysticetes. First, odontocetes echolocate to find prey, which means
that they actively send out sounds to detect their prey. While there
are many strategies for hunting, one common pattern, especially for
deeper diving species, is many repeated deep dives within a bout, and
multiple bouts within a day, to find and catch prey. As discussed
above, studies demonstrate that odontocetes may cease their foraging
dives in response to sound exposure. If enough foraging interruptions
occur over multiple sequential days, and the individual either does not
take in the necessary food, or must exert significant effort to find
necessary food elsewhere, energy budget deficits can occur that could
potentially result in impacts to reproductive success, such as
increased cow/calf intervals (the time between successive calving).
Second, while many mysticetes rely on seasonal migratory patterns that
position them in a geographic location at a specific time of the year
to take advantage of ephemeral large abundances of prey (i.e.,
invertebrates or small fish, which they eat by the thousands),
odontocetes forage more homogeneously on one fish or squid at a time.
Therefore, if odontocetes are interrupted while feeding, it is often
possible to find more prey relatively nearby.
Dwarf Sperm Whales and Pygmy Sperm Whales
In this section, we bring together the discussion of marine mammals
generally and odontocetes in particular regarding the different types
and amounts of take that different species will incur, the applicable
mitigation for each species, and the status of the species to support
the negligible impact determinations for each. We have previously
described the unlikelihood of any masking or habitat impacts to any
marine mammals that would rise to the level of affecting individual
fitness.
In Table 52 below for dwarf sperm whales and pygmy sperm whales, we
indicate the total annual numbers of take by Level A and Level B
harassment, and a number indicating the instances of total take as a
percentage of abundance.
[[Page 5887]]
Table 52--Annual Estimated Takes by Level B Harassment and Level A Harassment for Dwarf Sperm Whales and Pygmy Sperm Whales and Number Indicating the
Instances of Total Take as a Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Instances of indicated types of incidental take (not all takes Abundance Instances of total take
represent separate individuals, especially for disturbance) -------------------------- as percentage of
----------------------------------------------------------------- abundance
Level B harassment Level A Total takes -------------------------
Species -------------------------- harassment -------------------------- MITT study
------------- MITT study MITT study area + MITT study
Behavioral MITT study area + area transit MITT study area +
disturbance TTS PTS area transit corridor area transit
corridor corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dwarf sperm whale.................. 1,353 7,147 50 8,502 8,550 25,594 27,396 33 31
Pygmy sperm whale.................. 534 2,876 20 3,412 3,430 10,431 11,169 33 31
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
Estimated Take of Marine Mammals section.
As discussed above, the majority of Level B harassment behavioral
takes of odontocetes, and thereby dwarf and pygmy sperm whales, is
expected to be in the form of low to occasionally moderate severity of
a generally shorter duration. As mentioned earlier in this section, we
anticipate more severe effects from takes when animals are exposed to
higher received levels or for longer durations. Occasional milder Level
B behavioral harassment, as is expected here, is unlikely to cause
long-term consequences for either individual animals or populations,
even if some smaller subset of the takes are in the form of a longer
(several hours or a day) and more moderate response.
We note that dwarf and pygmy sperm whales, as HF-sensitive species,
have a lower PTS threshold than all other groups and therefore are
likely to experience larger amounts of TTS and PTS, and NMFS
accordingly has evaluated and would authorize higher numbers. However,
Kogia whales are still likely to avoid sound levels that would cause
higher levels of TTS (greater than 20 dB) or PTS. Therefore, even
though the number of TTS and PTS takes are higher than for other
odontocetes, for all of the reasons described above TTS and PTS are not
expected to impact reproduction or survival of any individual.
Below we compile and summarize the information that supports our
preliminary determination that the Navy's activities would not
adversely affect pygmy and dwarf sperm whales through effects on annual
rates of recruitment or survival.
Neither pygmy sperm whales nor dwarf sperm whales are listed under
the ESA. The stock structure for both pygmy and dwarf sperm whales
remains uncertain in the western Pacific, and dwarf sperm whales in the
MITT Study Area have not been assigned to a stock in the current SAR
(Carretta et al., 2017c; Carretta et al., 2017d). Due to their pelagic
distribution, small size, and cryptic behavior, pygmy sperm whales and
dwarf sperm whales are rarely sighted during at-sea surveys and are
difficult to distinguish between when visually observed in the field.
There were no species of Kogia sighted during the 2007 shipboard survey
within the MITT Study Area (Fulling et al., 2011), but three Kogia were
observed during marine mammal monitoring for Valiant Shield 2007 about
8 NM east of Guam (Mobley, 2007). In total, during Navy-funded 2010-
2016 small boat surveys in the Mariana Islands, five dwarf sperm whales
have been encountered on four occasions in a median depth of
approximately 750 m and at a median distance of approximately 3 km from
shore (Hill et al., 2017a). The stranding of a pygmy sperm whale in
1997 (Trianni and Tenorio, 2012) is the only other confirmed occurrence
of this species in the MITT Study Area.
No mortality or tissue damage is anticipated or proposed to be
authorized. Both pygmy and dwarf sperm whales would benefit from the
procedural mitigation measures described earlier in the Proposed
Mitigation Measures section. Regarding the magnitude of Level B
harassment takes (TTS and behavioral disruption), the number of
estimated total instances of take compared to the abundance is 33
percent for both dwarf and pygmy sperm whales in the MITT Study Area
and 31 percent in the MITT Study Area and the transit corridor
combined, which suggest that some portion of these two species would be
taken on one to a few days per year (Table 52). As to the severity of
those individual Level B harassment takes by behavioral disruption, the
duration of any exposure is expected to be between minutes and hours
(i.e., relatively short) and the received sound levels largely below
172 dB (i.e., of a lower, to occasionally moderate, level and less
likely to evoke a severe response). As to the severity of TTS takes,
they are expected to be low-level, of short duration, and mostly not in
a frequency band that would be expected to interfere with dwarf or
pygmy sperm whale communication or other important low-frequency cues,
and the associated lost opportunities and capabilities are not at a
level that would impact reproduction or survival. Some Level A
harassment by PTS is anticipated annually (50 and 20 takes for Dwarf
and pygmy whale, respectively, see Table 52). For these same reasons
(low level and frequency band), while a small permanent loss of hearing
sensitivity (PTS) may include some degree of energetic costs for
compensating or may mean some small loss of opportunities or detection
capabilities, at the expected scale the estimated Level A harassment
takes by PTS for dwarf and pygmy sperm whales would be unlikely to
impact behaviors, opportunities, or detection capabilities to a degree
that would interfere with reproductive success or survival of any
individuals, let alone affect annual rates of recruitment or survival.
For these reasons, in consideration of all of the effects of the Navy's
activities combined, we have preliminary determined that the proposed
authorized take will have a negligible impact on pygmy and dwarf sperm
whales.
Sperm Whale
In this section, we bring together the discussion of marine mammals
generally and odontocetes in particular to evaluate the different types
and amounts of take that sperm whales would incur, the applicable
mitigation, and the status of the species to support the negligible
impact determination. We have previously described the unlikelihood of
any masking or habitat
[[Page 5888]]
impacts to any marine mammals that would rise to the level of affecting
individual fitness. In Table 53 below for sperm whales, we indicate the
total annual numbers of take by Level A and Level B harassment, and a
number indicating the instances of total take as a percentage of
abundance.
Table 53--Annual Estimated Takes by Level B Harassment and Level A Harassment for Sperm Whales and Number Indicating the Instances of Total Take as a
Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Instances of indicated types of incidental take (not all takes Abundance Instances of total take
represent separate individuals, especially for disturbance) -------------------------- as percentage of
----------------------------------------------------------------- abundance
Level B harassment Level A Total takes -------------------------
Species -------------------------- harassment -------------------------- MITT study
------------- MITT study MITT study area + MITT study
Behavioral MITT Study area + area transit MITT study area +
disturbance TTS PTS area transit corridor area transit
corridor corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale........................ 192 11 0 189 203 705 1,635 27 12
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
Estimated Take of Marine Mammals section.
The stock structure for sperm whales remains uncertain in the
Pacific (Mesnick et al., 2011; Mizroch and Rice, 2013; NMFS, 2015a),
and sperm whales in the MITT Study Area have not been assigned to a
stock in the current Pacific SAR (Carretta et al., 2017b; Carretta et
al., 2017c). Sperm whales have been routinely sighted in the MITT Study
Area and detected in acoustic monitoring records. Acoustic recordings
in August 2013 at Pagan Island indicated the presence of sperm whales
within 20 NM of the island (Tetra Tech Inc., 2014). Although it has
been reported that sperm whales are generally found far offshore in
deep water (Mizroch and Rice, 2013), sightings in the MITT Study Area
have included animals close to shore in relatively shallow water as
well as in areas near steep bathymetric relief (Fulling et al., 2011;
Hill et al., 2017a; Uyeyama, 2014). A total of 23 sperm whale sightings
and 93 acoustic encounters were made during the 2007 survey in water
depths between approximately 400 and 1,000 m depth (Fulling et al.,
2011; Yack et al., 2016). During the Navy-funded 2010-2016 small boat
surveys in the Mariana Islands, six sperm whales were encountered on
three occasions in a median depth of approximately 1,200 m and median
approximate distance from shore of 12 km (Hill et al., 2017a).
Vocalizations classified as sperm whales were also detected on 20
occasions to the east and south of Guam by passive acoustic recorders
during an underwater glider survey in 2014 (Klinck et al., 2016b).
Below we compile and summarize the information that supports our
preliminary determination that the Navy's activities would not
adversely affect sperm whales through effects on annual rates of
recruitment or survival.
The sperm whale is listed as endangered under the ESA. No mortality
or Level A harassment is anticipated or proposed to be authorized.
Sperm whales would benefit from the procedural mitigation measures
described earlier in the Proposed Mitigation Measures section.
Regarding the magnitude of Level B harassment takes (TTS and behavioral
disruption), the number of estimated total instances of take compared
to the abundance is 27 percent in the MITT Study Area and 12 percent in
the MITT Study Area and transit corridor combined (Table 53), which
suggests that some portion of the sperm whales in the MITT Study Area
would be taken on one to a few days per year. Regarding the severity of
those individual Level B harassment takes by behavioral disruption, the
duration of any exposure is expected to be between minutes and hours
(i.e., relatively short) and the received sound levels largely below
172 dB (i.e., of a lower, to occasionally moderate, level and less
likely to evoke a severe response). Regarding the severity of TTS
takes, they are expected to be low-level, of short duration, and mostly
not in a frequency band that would be expected to interfere with
important low-frequency cues. While the narrowband/single frequency
threshold shift incurred may overlap with parts of the frequency range
that sperm whales use for communication, any associated lost
opportunities and capabilities would not be at a level that would
impact reproduction or survival. Any individual whale is likely to be
disturbed at a low-moderate level, with the taken individuals likely
exposed on one day. This low magnitude and severity of harassment
effects is not expected to result in impacts on individual reproduction
or survival. For these reasons, we have preliminarily determined, in
consideration of all of the effects of the Navy's activities combined,
that the proposed authorized take would have a negligible impact on
sperm whales.
Beaked Whales
In this section, we build on the broader odontocete discussion
above (i.e., that information applies to beaked whales as well), except
where we offer alternative information about the received levels for
beaked whale Level B behavioral harassment. We bring together the
discussion of the different types and amounts of take that different
species will incur, the applicable mitigation for each species, and the
status of each species to support the negligible impact determination
for each species.
We have previously described the unlikelihood of any masking or
habitat impacts to any groups that would rise to the level of affecting
individual fitness. The discussion below focuses on additional
information that is specific to beaked whales (in addition to the
general information on odontocetes provided above, which is relevant to
these species) to support the conclusions for each species.
In Table 54 below for beaked whales, we indicate the total annual
numbers of take by Level A and Level B harassment, and a number
indicating the instances of total take as a percentage of abundance.
[[Page 5889]]
Table 54--Annual Estimated Takes by Level B Harassment and Level A Harassment for Beaked Whales and Number Indicating the Instances of Total Take as a
Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Instances of indicated types of incidental take (not all takes Abundance Instances of total take
represent separate individuals, especially for disturbance) -------------------------- as percentage of
----------------------------------------------------------------- abundance
Level B Harassment Level A Total Takes -------------------------
Species -------------------------- harassment -------------------------- MITT study
------------- MITT study MITT study area + MITT study
Behavioral MITT study area + area transit MITT study area +
disturbance TTS PTS area transit corridor area transit
corridor corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blainville's beaked whale.......... 1,691 27 0 1,698 1,719 3,083 3,376 55 51
Cuvier's beaked whale.............. 642 4 0 534 647 1,075 2,642 50 24
Ginkgo-toothed beaked whale........ 3,660 65 0 3,662 3,725 6,775 7,567 54 49
Longman's beaked whale............. 5,959 107 0 6,056 6,066 11,148 11,253 54 54
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
Estimated Take of Marine Mammals section.
This first paragraph provides specific information that is in lieu
of the parallel information provided for odontocetes as a whole. The
majority of takes by harassment of beaked whales in the MITT Study Area
are caused by sources from the MF1 active sonar bin (which includes
hull-mounted sonar) because they are high level narrowband sources that
fall within the 1-10 kHz range, which overlap a more sensitive portion
(though not the most sensitive) of the MF hearing range. Also, of the
sources expected to result in take, they are used in a large portion of
exercises (see Table 1.5-1 in the Navy's rulemaking/LOA application).
Most of the takes (96 percent) from the MF1 bin in the MITT Study Area
would result from received levels between 148 and 160 dB SPL. For the
remaining active sonar bin types, the percentages are as follows: LF4 =
99 percent between 124 and 136 dB SPL, MF4 = 98 percent between 130 and
148 dB SPL, MF5 = 97 percent between 100 and 142 dB SPL, and HF4 = 95
percent between 100 and 148 dB SPL. These values may be derived from
the information in Tables 6.4-8 through 6.4-12 in the Navy's
rulemaking/LOA application (though they were provided directly to NMFS
upon request). Given the levels they are exposed to and their
sensitivity, some responses would be of a lower severity, but many
would likely be considered moderate.
Research has shown that beaked whales are especially sensitive to
the presence of human activity (Pirotta et al., 2012; Tyack et al.,
2011) and therefore have been assigned a lower harassment threshold,
with lower received levels resulting in a higher percentage of
individuals being harassed and a more distant distance cutoff (50 km
for high source level, 25 km for moderate source level).
Beaked whales have been documented to exhibit avoidance of human
activity or respond to vessel presence (Pirotta et al., 2012). Beaked
whales were observed to react negatively to survey vessels or low
altitude aircraft by quick diving and other avoidance maneuvers, and
none were observed to approach vessels (Wursig et al., 1998). It has
been speculated for some time that beaked whales might have unusual
sensitivities to sonar sound due to their likelihood of stranding in
conjunction with MFAS use, although few definitive causal relationships
between MFAS use and strandings have been documented (see Potential
Effects of Specified Activities on Marine Mammals and their Habitat
section).
Research and observations show that if beaked whales are exposed to
sonar or other active acoustic sources, they may startle, break off
feeding dives, and avoid the area of the sound source to levels of 157
dB re 1 [micro]Pa, or below (McCarthy et al., 2011). Acoustic
monitoring during actual sonar exercises revealed some beaked whales
continuing to forage at levels up to 157 dB re 1 [micro]Pa (Tyack et
al., 2011). Stimpert et al. (2014) tagged a Baird's beaked whale, which
was subsequently exposed to simulated MFAS. Changes in the animal's
dive behavior and locomotion were observed when received level reached
127 dB re 1 [mu]Pa. However, Manzano-Roth et al. (2013) found that for
beaked whale dives that continued to occur during MFAS activity,
differences from normal dive profiles and click rates were not detected
with estimated received levels up to 137 dB re 1 [micro]Pa while the
animals were at depth during their dives. In research done at the
Navy's fixed tracking range in the Bahamas, animals were observed to
leave the immediate area of the anti-submarine warfare training
exercise (avoiding the sonar acoustic footprint at a distance where the
received level was ``around 140 dB SPL, according to Tyack et al.
(2011)), but return within a few days after the event ended (Claridge
and Durban, 2009; McCarthy et al., 2011; Moretti et al., 2009, 2010;
Tyack et al., 2010, 2011). Tyack et al. (2011) report that, in reaction
to sonar playbacks, most beaked whales stopped echolocating, made long
slow ascent to the surface, and moved away from the sound. A similar
behavioral response study conducted in Southern California waters
during the 2010-2011 field season found that Cuvier's beaked whales
exposed to MFAS displayed behavior ranging from initial orientation
changes to avoidance responses characterized by energetic fluking and
swimming away from the source (DeRuiter et al., 2013b). However, the
authors did not detect similar responses to incidental exposure to
distant naval sonar exercises at comparable received levels, indicating
that context of the exposures (e.g., source proximity, controlled
source ramp-up) may have been a significant factor. The study itself
found the results inconclusive and meriting further investigation.
Cuvier's beaked whale responses suggested particular sensitivity to
sound exposure consistent with results for Blainville's beaked whale.
Populations of beaked whales and other odontocetes on the Bahamas
and other Navy fixed ranges that have been operating for decades appear
to be stable. Behavioral reactions (avoidance of the area of Navy
activity) seem likely in most cases if beaked whales are exposed to
anti-submarine sonar within a few tens of kilometers, especially for
prolonged periods (a few hours or more) since this is one of the most
sensitive marine mammal groups to anthropogenic sound of any species or
group studied to date and research indicates beaked whales will leave
an
[[Page 5890]]
area where anthropogenic sound is present (De Ruiter et al., 2013;
Manzano-Roth et al., 2013; Moretti et al., 2014; Tyack et al., 2011).
Research involving tagged Cuvier's beaked whales in the SOCAL Range
Complex reported on by Falcone and Schorr (2012, 2014) indicates year-
round prolonged use of the Navy's training and testing area by these
beaked whales and has documented movements in excess of hundreds of
kilometers by some of those animals. Given that some of these animals
may routinely move hundreds of kilometers as part of their normal
pattern, leaving an area where sonar or other anthropogenic sound is
present may have little, if any, cost to such an animal. Photo
identification studies in the SOCAL Range Complex, a Navy range that is
utilized for training and testing, have identified approximately 100
Cuvier's beaked whale individuals with 40 percent having been seen in
one or more prior years, with re-sightings up to seven years apart
(Falcone and Schorr, 2014). These results indicate long-term residency
by individuals in an intensively used Navy training and testing area,
which may also suggest a lack of long-term consequences as a result of
exposure to Navy training and testing activities. More than eight years
of passive acoustic monitoring on the Navy's instrumented range west of
San Clemente Island documented no significant changes in annual and
monthly beaked whale echolocation clicks, with the exception of
repeated fall declines likely driven by natural beaked whale life
history functions (DiMarzio et al., 2018). Finally, results from
passive acoustic monitoring estimated that regional Cuvier's beaked
whale densities were higher than indicated by the NMFS' broad scale
visual surveys for the U.S. west coast (Hildebrand and McDonald, 2009).
Below we compile and summarize the information that supports our
preliminary determination that the Navy's activities would not
adversely affect beaked whales through effects on annual rates of
recruitment or survival.
These beaked whale species are not listed as endangered or
threatened species under the ESA. No mortality or Level A harassment is
expected or proposed for authorization. All of the beaked whales
species discussed in this section would benefit from the procedural
mitigation measures described earlier in the Proposed Mitigation
Measures section. Regarding the magnitude of Level B harassment takes
(TTS and behavioral disruption), the number of estimated instances of
take compared to the abundance is 50 to 55 percent in the MITT Study
Area and 24 to 54 percent in the MITT Study Area and transit corridor
combined (Table 54). This information suggests that up to half of the
individuals of these species could be impacted, if each were taken only
one day per year, though the more likely scenario is that a smaller
portion than that would be taken, and a subset of them would be taken
on a few days. Regarding the severity of those individual Level B
harassment takes by behavioral disruption, the duration of any exposure
is expected to be between minutes and hours (i.e., relatively short)
and the received sound levels largely below 160 dB, though with beaked
whales, which are considered somewhat more sensitive, this could mean
that some individuals will leave preferred habitat for a day (i.e.,
moderate level takes). However, while interrupted feeding bouts are a
known response and concern for odontocetes, we also know that there are
often viable alternative habitat options nearby. Regarding the severity
of TTS takes, they are expected to be low-level, of short duration, and
mostly not in a frequency band that would be expected to interfere with
beaked whale communication or other important low-frequency cues, and
that the associated lost opportunities and capabilities are not at a
level that would impact reproduction or survival.
As mentioned earlier in the odontocete overview, we anticipate more
severe effects from takes when animals are exposed to higher received
levels or sequential days of impacts. Occasional instances of take by
Level B behavioral harassment of a low to moderate severity are
unlikely to affect reproduction or survival. Here, some small number of
takes by Level B behavioral harassment could be in the form of a longer
(several hours or a day) and more moderate response, and/or some small
number could be taken over several days, but not at a level that would
impact reproduction or survival.
This low magnitude and low to moderate severity of harassment
effects is not expected to result in impacts on individual reproduction
or survival. For these reasons, we have preliminarily determined, in
consideration of all of the effects of the Navy's activities combined,
that the proposed authorized take would have a negligible impact on
beaked whales.
Small Whales and Dolphins
This section builds on the broader discussion above and compiles
the discussion of the different types and amounts of take that
different small whale and dolphin species may incur, the applicable
mitigation for dolphin and small whale species, and the status of the
species to support the negligible impact determinations. We have
previously described the unlikelihood of any masking or habitat impacts
to any groups that would rise to the level of affecting individual
fitness. The discussion below focuses on additional information that is
specific to these species (in addition to the general information on
odontocetes provided above, which is relevant to these species) to
support the conclusions for each species.
In Table 55 below for dolphins and small whales, we indicate the
total annual numbers of take by Level A and Level B harassment, and a
number indicating the instances of total take as a percentage of
abundance.
Table 55--Annual Estimated Takes by Level B Harassment and Level A Harassment for Dolphins and Small Whales and Number Indicating the Instances of Total
Take as a Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Instances of indicated types of incidental take (not all takes Abundance Instances of total take
represent separate individuals, especially for disturbance) -------------------------- as percentage of
----------------------------------------------------------------- abundance
Level B harassment Level A Total takes -------------------------
Species -------------------------- harassment -------------------------- MITT study
------------- MITT study MITT study area + MITT study
Behavioral MITT study area + area transit MITT study area +
disturbance TTS PTS area transit corridor area transit
corridor corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bottlenose dolphin................. 116 21 0 132 137 753 1,075 17 13
False killer whale................. 641 121 0 759 762 3,979 4,218 19 18
Fraser's dolphin................... 11,327 1,952 1 13,261 13,280 75,420 76,476 18 17
Killer whale....................... 36 8 0 44 44 215 253 20 17
Melon-headed whale................. 2,306 508 0 2,798 2,814 15,342 16,461 18 17
Pantropical spotted dolphin........ 12,078 2,818 1 14,820 14,897 81,013 85,755 18 17
[[Page 5891]]
Pygmy killer whale................. 87 17 0 103 104 502 527 21 20
Risso's dolphin.................... 2,650 519 0 3,166 3,169 16,991 17,184 19 18
Rough-toothed dolphin.............. 161 36 0 185 197 1,040 1,815 18 11
Short-finned pilot whale........... 987 177 0 1,150 1,164 5,700 6,583 20 18
Spinner dolphin.................... 1,185 229 1 1,404 1,415 2,975 3,759 47 38
Striped dolphin.................... 3,256 751 0 3,956 4,007 22,081 24,528 18 16
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
Estimated Take of Marine Mammals section.
As described above, the large majority of Level B behavioral
harassment to odontocetes, and thereby dolphins and small whales, from
hull-mounted sonar (MF1) in the MITT Study Area would result from
received levels between 160 and 172 dB SPL. Therefore, the majority of
Level B harassment takes are expected to be in the form of low to
occasionally moderate responses of a generally shorter duration. As
mentioned earlier in this section, we anticipate more severe effects
from takes when animals are exposed to higher received levels.
Occasional milder occurrences of Level B behavioral harassment are
unlikely to cause long-term consequences for individual animals or
populations that have any effect on reproduction or survival.
Research and observations show that if delphinids are exposed to
sonar or other active acoustic sources they may react in a number of
ways depending on their experience with the sound source and what
activity they are engaged in at the time of the acoustic exposure.
Delphinids may not react at all until the sound source is approaching
within a few hundred meters to within a few kilometers depending on the
environmental conditions and species. Some dolphin species (the more
surface-dwelling taxa--typically those with ``dolphin'' in the common
name, such as bottlenose dolphins, spotted dolphins, spinner dolphins,
rough-toothed dolphins, etc., but not Risso's dolphin), especially
those residing in more industrialized or busy areas, have demonstrated
more tolerance for disturbance and loud sounds and many of these
species are known to approach vessels to bow-ride. These species are
often considered generally less sensitive to disturbance. Dolphins and
small whales that reside in deeper waters and generally have fewer
interactions with human activities are more likely to demonstrate more
typical avoidance reactions and foraging interruptions as described
above in the odontocete overview.
All the dolphin and small whale species discussed in this section
would benefit from the procedural mitigation measures described earlier
in the Proposed Mitigation Measures section. Additionally, the Agat Bay
Nearshore Geographic Mitigation Area will provide protection for
spinner dolphins as the Navy will not use in-water explosives or MF1
ship hull-mounted mid-frequency active sonar in this area. High use
areas for spinner dolphins including Agat Bay are where animals
congregate during the day to rest (Amesbury et al., 2001; Eldredge,
1991). Behavioral disruptions during resting periods can adversely
impact health and energetic budgets by not allowing animals to get the
needed rest and/or by creating the need to travel and expend additional
energy to find other suitable resting areas. Avoiding sonar and
explosives in this area reduces the likelihood of impacts that would
affect reproduction and survival.
Below we compile and summarize the information that supports our
preliminary determination that the Navy's activities would not
adversely affect dolphins and small whales through effects on annual
rates of recruitment or survival.
None of the small whale and dolphin species are listed as
endangered or threatened species under the ESA. No mortality or Level A
harassment is anticipated or proposed to be authorized, with the
exception of one Level A harassment take by PTS each for spinner
dolphin, pantropical spotted dolphin, and Fraser's dolphin. No tissue
damage is anticipated or proposed to be authorized for any species.
Regarding the magnitude of Level B harassment takes (TTS and behavioral
disruption), the number of estimated total instances of take compared
to the abundance is 47 percent for spinner dolphins and 17 to 21
percent for the remaining dolphins and small whales in the MITT Study
Area, which suggests that some portion of these species would be taken
on one to a few days per year. Additionally, the number of estimated
total instances of take compared to the abundance is 38 percent for
spinner dolphins and 20 percent or less for the remaining dolphins and
small whales in the MITT Study and transit corridor combined, which
would also suggest that some portion of these species would be taken on
one to a few days per year (Table 55). As to the severity of those
individual Level B harassment takes by behavioral disruption, the
duration of any exposure is expected to be between minutes and hours
(i.e., relatively short) and the received sound levels largely below
172 dB (i.e., of a lower, to occasionally moderate, level and less
likely to evoke a severe response). As to the severity of TTS takes,
they are expected to be low-level, of short duration, and mostly not in
a frequency band that would be expected to interfere with communication
or other important low-frequency cues. The associated lost
opportunities and capabilities are not at a level that would impact
reproduction or survival. Any individual dolphin or small whale is
likely to be disturbed at a low-moderate level, with the taken
individuals likely exposed on one to a few days. This low magnitude and
severity of harassment effects is not expected to result in impacts on
individual reproduction or survival. Three species (spinner dolphin,
Fraser's dolphin, and pantropical spotted
[[Page 5892]]
dolphin) could be taken by one PTS annually of likely low severity. A
small permanent loss of hearing sensitivity (PTS) may include some
degree of energetic costs for compensating or may mean some small loss
of opportunities or detection capabilities, but at the expected scale
the estimated Level A harassment takes by PTS for spinner dolphin,
Fraser's dolphin, and pantropical spotted dolphin would be unlikely to
impact behaviors, opportunities, or detection capabilities to a degree
that would interfere with reproductive success or survival of any
individuals, let alone affect annual rates of recruitment or survival.
For these reasons, we have preliminarily determined, in consideration
of all of the effects of the Navy's activities combined, that the
proposed authorized take would have a negligible impact on small whales
and dolphins.
Altogether, only a small portion of any odontocete population is
anticipated to be impacted, and any individual whale or dolphin is
likely to be disturbed at a low-moderate level, with the taken
individuals likely exposed on one day or a few days. This low magnitude
and severity of harassment effects is unlikely to result in impacts on
individual reproduction or survival, much less annual rates of
recruitment or survival of any of the species. For these reasons, we
have preliminarily determined, in consideration of all of the effects
of the Navy's activities combined, that the proposed authorized take
would have a negligible impact on all of the odontocete species.
Preliminary Determination
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the proposed monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the Specified Activities will have a negligible impact
on all affected marine mammal species.
Subsistence Harvest of Marine Mammals
There are no subsistence uses or harvest of marine mammals in the
geographic area affected by the specified activities. Therefore, NMFS
has preliminarily determined that the total taking affecting species
would not have an unmitigable adverse impact on the availability of the
species for taking for subsistence purposes.
Classifications
Endangered Species Act
There are five marine mammal species under NMFS jurisdiction that
are listed as endangered or threatened under the ESA with confirmed or
possible occurrence in the MITT Study Area: Blue whale, fin whale,
humpback whale, sei whale, and sperm whale. There is no ESA-designated
critical habitat for any species in the MITT Study Area. The Navy will
consult with NMFS pursuant to section 7 of the ESA for MITT Study Area
activities. NMFS will also consult internally on the issuance of the
regulations and LOA under section 101(a)(5)(A) of the MMPA. NMFS'
Permits and Conservation Division is currently discussing the Navy
rulemaking/LOA application with NMFS' ESA Interagency Cooperation
Division.
National Marine Sanctuaries Act
There are no national marine sanctuaries in the MITT Study Area.
Therefore, no consultation under the National Marine Sanctuaries Act is
required.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must evaluate our proposed actions and alternatives with respect
to potential impacts on the human environment. Accordingly, NMFS plans
to adopt the Navy's EIS/OEIS for the MITT Study Area provided our
independent evaluation of the document finds that it includes adequate
information analyzing the effects on the human environment of issuing
regulations and an LOA under the MMPA. NMFS is a cooperating agency on
the 2019 MITT DEIS/OEIS and has worked extensively with the Navy in
developing the document. The 2019 MITT DEIS/OEIS was made available for
public comment at http://www.MITT-eis.com, January 2019. We will review
all comments submitted in response to this notice prior to concluding
our NEPA process or making a final decision on the MMPA rule and LOA
request.
Regulatory Flexibility Act
The Office of Management and Budget has determined that this
proposed rule is not significant for purposes of Executive Order 12866.
Pursuant to the Regulatory Flexibility Act (RFA), the Chief Counsel
for Regulation of the Department of Commerce has certified to the Chief
Counsel for Advocacy of the Small Business Administration that this
proposed rule, if adopted, would not have a significant economic impact
on a substantial number of small entities. The RFA requires Federal
agencies to prepare an analysis of a rule's impact on small entities
whenever the agency is required to publish a notice of proposed
rulemaking. However, a Federal agency may certify, pursuant to 5 U.S.C.
605(b), that the action will not have a significant economic impact on
a substantial number of small entities. The Navy is the sole entity
that would be affected by this rulemaking, and the Navy is not a small
governmental jurisdiction, small organization, or small business, as
defined by the RFA. Any requirements imposed by an LOA issued pursuant
to these regulations, and any monitoring or reporting requirements
imposed by these regulations, would be applicable only to the Navy.
NMFS does not expect the issuance of these regulations or the
associated LOA to result in any impacts to small entities pursuant to
the RFA. Because this action, if adopted, would directly affect the
Navy and not a small entity, NMFS concludes that the action would not
result in a significant economic impact on a substantial number of
small entities.
List of Subjects in 50 CFR Part 218
Exports, Fish, Imports, Incidental take, Indians, Labeling, Marine
mammals, Navy, Penalties, Reporting and recordkeeping requirements,
Seafood, Sonar, Transportation.
Dated: January 9, 2020.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.
For reasons set forth in the preamble, 50 CFR part 218 is proposed
to be amended as follows:
PART 218--REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE
MAMMALS
0
1. The authority citation for part 218 continues to read as follows:
Authority: 16 U.S.C. 1361 et seq., unless otherwise noted.
0
2. Revise subpart J to part 218 to read as follows:
Subpart J--Taking and Importing Marine Mammals; U.S. Navy's Mariana
Islands Training and Testing (MITT)
Sec.
218.90 Specified activity and geographical region.
218.91 Effective dates.
218.92 Permissible methods of taking.
[[Page 5893]]
218.93 Prohibitions.
218.94 Mitigation requirements.
218.95 Requirements for monitoring and reporting.
218.96 Letters of Authorization.
218.97 Renewals and modifications of Letters of Authorization.
218.98 [Reserved]
Subpart J--Taking and Importing Marine Mammals; U.S. Navy's Mariana
Islands Training and Testing (MITT)
Sec. 218.90 Specified activity and geographical region.
(a) Regulations in this subpart apply only to the U.S. Navy (Navy)
for the taking of marine mammals that occurs in the area described in
paragraph (b) of this section and that occurs incidental to the
activities listed in paragraph (c) of this section.
(b)(1) The taking of marine mammals by the Navy under this subpart
may be authorized in a Letter of Authorization (LOA) only if it occurs
within the Mariana Islands Training and Testing (MITT) Study Area. The
MITT Study Area is comprised of three components:
(i) The Mariana Islands Range Complex (MIRC);
(ii) Additional areas on the high seas; and
(iii) A transit corridor between the MIRC and the Hawaii Range
Complex (HRC).
(2) The MIRC includes the waters south of Guam to north of Pagan
(Commonwealth of the Northern Mariana Islands (CNMI)), and from the
Pacific Ocean east of the Mariana Islands to the Philippine Sea to the
west, encompassing 501,873 square nautical miles (NM\2\) of open ocean.
For the additional areas of the high seas, this includes the area to
the north of the MIRC that is within the U.S. Exclusive Economic Zone
(EEZ) of the CNMI and the areas to the west of the MIRC. The transit
corridor is outside the geographic boundaries of the MIRC and
represents a great circle route (i.e., the shortest distance) across
the high seas for Navy ships transiting between the MIRC and the HRC.
Additionally, the MITT Study Area includes pierside locations in the
Apra Harbor Naval Complex.
(c) The taking of marine mammals by the Navy is only authorized if
it occurs incidental to the Navy conducting training and testing
activities, including:
(1) Training. (i) Amphibious warfare;
(ii) Anti-submarine warfare;
(iii) Mine warfare;
(vi) Surface warfare; and
(vii) Other training activities.
(2) Testing. (i) Naval Air Systems Command Testing Activities;
(ii) Naval Sea System Command Testing Activities; and
(iii) Office of Naval Research Testing Activities.
Sec. 218.91 Effective dates.
Regulations in this subpart are effective from [DATE OF PUBLICATION
OF FINAL RULE IN THE Federal Register] through August 3, 2027.
Sec. 218.92 Permissible methods of taking.
(a) Under an LOA issued pursuant to Sec. Sec. 216.106 of this
chapter and 218.96, the Holder of the LOA (hereinafter ``Navy'') may
incidentally, but not intentionally, take marine mammals within the
area described in Sec. 218.90(b) by Level A harassment and Level B
harassment associated with the use of active sonar and other acoustic
sources and explosives, provided the activity is in compliance with all
terms, conditions, and requirements of these regulations in this
subpart and the applicable LOAs.
(b) The incidental take of marine mammals by the activities listed
in Sec. 218.90(c) is limited to the following species:
Table 1 to Sec. 218.92
------------------------------------------------------------------------
Species Scientific Name
------------------------------------------------------------------------
Blue whale................................ Balaenoptera musculus
Bryde's whale............................. Balaenoptera edeni
Fin whale................................. Balaenoptera physalus
Humpback whale............................ Megaptera novaeangliae
Minke whale............................... Balaenoptera acutorostrata
Omura's whale............................. Balaenoptera omurai
Sei whale................................. Balaenoptera borealis
Blainville's beaked whale................. Mesoplodon densirostris
Common bottlenose dolphin................. Tursiops truncatus
Cuvier's beaked whale..................... Ziphius cavirostris
Dwarf sperm whale......................... Kogia sima
False killer whale........................ Pseudorca crassidens
Fraser's dolphin.......................... Lagenodelphis hosei
Ginkgo-toothed beaked whale............... Mesoplodon ginkgodens
Killer whale.............................. Orcinus orca
Longman's beaked whale.................... Indopacetus pacificus
Melon-headed whale........................ Peponocephala electra
Pantropical spotted dolphin............... Stenella attenuata
Pygmy killer whale........................ Feresa attenuata
Pygmy sperm whale......................... Kogia breviceps
Risso's dolphin........................... Grampus griseus
Rough-toothed dolphin..................... Steno bredanensis
Short-finned pilot whale.................. Globicephala macrorhynchus
Sperm whale............................... Physeter macrocephalus
Spinner dolphin........................... Stenella longirostris
Striped dolphin........................... Stenella coeruleoalba
------------------------------------------------------------------------
Sec. 218.93 Prohibitions.
Notwithstanding incidental takings contemplated in Sec. 218.92(a)
and authorized by LOAs issued under Sec. Sec. 216.106 of this chapter
and 218.96, no person in connection with the activities listed in Sec.
218.90(c) may:
(a) Violate, or fail to comply with, the terms, conditions, and
requirements of this subpart or an LOA issued under Sec. Sec. 216.106
of this chapter and 218.96;
(b) Take any marine mammal not specified in Sec. 218.92(b);
(c) Take any marine mammal specified in Sec. 218.92(b) in any
manner other than as specified in the LOAs; or
(d) Take a marine mammal specified in Sec. 218.92(b) if NMFS
determines such taking results in more than a negligible impact on the
species or stocks of such marine mammal.
Sec. 218.94 Mitigation requirements.
When conducting the activities identified in Sec. 218.90(c), the
mitigation measures contained in any LOAs issued under Sec. Sec.
216.106 of this chapter and 218.96 must be implemented. These
mitigation measures include, but are not limited to:
(a) Procedural mitigation. Procedural mitigation is mitigation that
the Navy must implement whenever and wherever an applicable training or
testing activity takes place within the MITT Study Area for each
applicable activity category or stressor category and includes acoustic
stressors (i.e., active sonar and other transducers, weapons firing
noise), explosive stressors (i.e., sonobuoys, torpedoes, medium-caliber
and large-caliber projectiles, missiles and rockets, bombs, sinking
exercises, mines, anti-swimmer grenades), and physical disturbance and
strike stressors (i.e., vessel movement; towed in-water devices; small-
, medium-, and large-caliber non-explosive practice munitions; non-
explosive missiles and rockets; and non-explosive bombs and mine
shapes).
(1) Environmental awareness and education. Appropriate Navy
personnel (including civilian personnel) involved in mitigation and
training or testing activity reporting under the specified activities
will complete one or more modules of the U.S Navy Afloat Environmental
Compliance Training Series, as identified in their career path training
plan. Modules include: Introduction to the U.S. Navy Afloat
Environmental Compliance Training Series, Marine Species Awareness
Training; U.S. Navy Protective Measures Assessment Protocol; and U.S.
Navy Sonar Positional Reporting System and Marine Mammal Incident
Reporting.
(2) Active sonar. Active sonar includes low-frequency active sonar,
mid-frequency active sonar, and high-frequency active sonar. For
vessel-based activities, mitigation applies only to sources that are
positively controlled and deployed from manned surface vessels (e.g.,
sonar sources towed from manned surface platforms). For aircraft-based
activities, mitigation applies only to sources that are positively
controlled and deployed from manned aircraft that do not operate at
high altitudes (e.g., rotary-wing aircraft). Mitigation does not apply
to active sonar sources deployed from unmanned aircraft or aircraft
operating at high altitudes (e.g., maritime patrol aircraft).
[[Page 5894]]
(i) Number of Lookouts and observation platform--(A) Hull-mounted
sources. One Lookout for platforms with space or manning restrictions
while underway (at the forward part of a small boat or ship) and
platforms using active sonar while moored or at anchor (including
pierside); and two Lookouts for platforms without space or manning
restrictions while underway (at the forward part of the ship).
(B) Sources that are not hull-mounted sources. One Lookout on the
ship or aircraft conducting the activity.
(ii) Mitigation zone and requirements. (A) During the activity, at
1,000 yards (yd) Navy personnel must power down 6 decibels (dB), at 500
yd Navy personnel must power down an additional 4 dB (for a total of 10
dB), and at 200 yd Navy personnel must shut down for low-frequency
active sonar >=200 dB and hull-mounted mid-frequency active sonar; or
at 200 yd Navy personnel must shut down for low-frequency active sonar
<200 dB, mid-frequency active sonar sources that are not hull-mounted,
and high-frequency active sonar.
(B) Prior to the start of the activity (e.g., when maneuvering on
station), Navy personnel must observe the mitigation zone for marine
mammals; if marine mammals are observed, Navy personnel must relocate
or delay the start of active sonar transmission.
(C) During the activity for low-frequency active sonar at or above
200 dB and hull-mounted mid-frequency active sonar, Navy personnel must
observe the mitigation zone for marine mammals and power down active
sonar transmission by 6 dB if marine mammals are observed within 1,000
yd of the sonar source; power down by an additional 4 dB (for a total
of 10 dB total) if marine mammals are observed within 500 yd of the
sonar source; and cease transmission if marine mammals are observed
within 200 yd of the sonar source.
(D) During the activity for low-frequency active sonar below 200
dB, mid-frequency active sonar sources that are not hull mounted, and
high-frequency active sonar, Navy personnel must observe the mitigation
zone for marine mammals and cease active sonar transmission if marine
mammals are observed within 200 yd of the sonar source.
(E) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing or powering up active sonar transmission) until
one of the following conditions has been met: The animal is observed
exiting the mitigation zone; the animal is thought to have exited the
mitigation zone based on a determination of its course, speed, and
movement relative to the sonar source; the mitigation zone has been
clear from any additional sightings for 10 minutes (min) for aircraft-
deployed sonar sources or 30 min for vessel-deployed sonar sources; for
mobile activities, the active sonar source has transited a distance
equal to double that of the mitigation zone size beyond the location of
the last sighting; or for activities using hull-mounted sonar where a
dolphin(s) is observed in the mitigation zone, the Lookout concludes
that the dolphin(s) is deliberately closing in on the ship to ride the
ship's bow wave, and is therefore out of the main transmission axis of
the sonar (and there are no other marine mammal sightings within the
mitigation zone).
(3) Weapons firing noise. Weapons firing noise associated with
large-caliber gunnery activities.
(i) Number of Lookouts and observation platform. One Lookout must
be positioned on the ship conducting the firing. Depending on the
activity, the Lookout could be the same as the one provided for under
``Explosive medium-caliber and large-caliber projectiles'' or under
``Small-, medium-, and large-caliber non-explosive practice munitions''
in paragraphs (a)(8)(i) and (a)(17)(i) of this section.
(ii) Mitigation zone and requirements. (A) Thirty degrees on either
side of the firing line out to 70 yd from the muzzle of the weapon
being fired.
(B) Prior to the start of the activity, Navy personnel must observe
the mitigation zone for marine mammals; if marine mammals are observed,
Navy personnel must relocate or delay the start of weapons firing.
(C) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must cease weapons firing.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing weapons firing) until one of the following
conditions has been met: The animal is observed exiting the mitigation
zone; the animal is thought to have exited the mitigation zone based on
a determination of its course, speed, and movement relative to the
firing ship; the mitigation zone has been clear from any additional
sightings for 30 min; or for mobile activities, the firing ship has
transited a distance equal to double that of the mitigation zone size
beyond the location of the last sighting.
(6) Explosive sonobuoys--(i) Number of Lookouts and observation
platform. One Lookout must be positioned in an aircraft or on a small
boat. If additional platforms are participating in the activity, Navy
personnel positioned in those assets (e.g., safety observers,
evaluators) must support observing the mitigation zone for applicable
biological resources while performing their regular duties.
(ii) Mitigation zone and requirements. (A) 600 yd around an
explosive sonobuoy.
(B) Prior to the initial start of the activity (e.g., during
deployment of a sonobuoy field, which typically lasts 20-30 min), Navy
personnel must conduct passive acoustic monitoring for marine mammals
and use information from detections to assist visual observations. Navy
personnel also must visually observe the mitigation zone for marine
mammals; if marine mammals are observed, Navy personnel must relocate
or delay the start of sonobuoy or source/receiver pair detonations.
(C) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must cease sonobuoy or source/receiver pair detonations.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing detonations) until one of the following conditions
has been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the
sonobuoy; or the mitigation zone has been clear from any additional
sightings for 10 min when the activity involves aircraft that have fuel
constraints (e.g., helicopter), or 30 min when the activity involves
aircraft that are not typically fuel constrained.
(E) After completion of the activity (e.g., prior to maneuvering
off station), when practical (e.g., when platforms are not constrained
by fuel restrictions or mission-essential follow-on commitments), Navy
personnel must
[[Page 5895]]
observe for marine mammals in the vicinity of where detonations
occurred; if any injured or dead marine mammals are observed, Navy
personnel must follow established incident reporting procedures. If
additional platforms are supporting this activity (e.g., providing
range clearance), these Navy assets must assist in the visual
observation of the area where detonations occurred.
(7) Explosive torpedoes--(i) Number of Lookouts and observation
platform. One Lookout positioned in an aircraft. If additional
platforms are participating in the activity, Navy personnel positioned
in those assets (e.g., safety observers, evaluators) must support
observing the mitigation zone for applicable biological resources while
performing their regular duties.
(ii) Mitigation zone and requirements. (A) 2,100 yd around the
intended impact location.
(B) Prior to the initial start of the activity (e.g., during
deployment of the target), Navy personnel must conduct passive acoustic
monitoring for marine mammals and use the information from detections
to assist visual observations. Navy personnel also must visually
observe the mitigation zone for marine mammals; if marine mammals are
observed, Navy personnel must relocate or delay the start of firing.
(C) During the activity, Navy personnel must observe for marine
mammals. If marine mammals are observed, Navy personnel must cease
firing.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing firing) until one of the following conditions has
been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the
intended impact location; or the mitigation zone has been clear from
any additional sightings for 10 min when the activity involves aircraft
that have fuel constraints, or 30 min when the activity involves
aircraft that are not typically fuel constrained.
(E) After completion of the activity (e.g., prior to maneuvering
off station), Navy personnel must when practical (e.g., when platforms
are not constrained by fuel restrictions or mission-essential follow-on
commitments), observe for marine mammals in the vicinity of where
detonations occurred; if any injured or dead marine mammals are
observed, Navy personnel must follow established incident reporting
procedures. If additional platforms are supporting this activity (e.g.,
providing range clearance), these Navy assets must assist in the visual
observation of the area where detonations occurred.
(8) Explosive medium-caliber and large-caliber projectiles. Gunnery
activities using explosive medium-caliber and large-caliber
projectiles. Mitigation applies to activities using a surface target.
(i) Number of Lookouts and observation platform. One Lookout must
be on the vessel or aircraft conducting the activity. For activities
using explosive large-caliber projectiles, depending on the activity,
the Lookout could be the same as the one described in ``Weapons firing
noise'' in paragraph (a)(3)(i) of this section. If additional platforms
are participating in the activity, Navy personnel positioned in those
assets (e.g., safety observers, evaluators) must support observing the
mitigation zone for applicable biological resources while performing
their regular duties.
(ii) Mitigation zone and requirements. (A) 200 yd around the
intended impact location for air-to-surface activities using explosive
medium-caliber projectiles.
(B) 600 yd around the intended impact location for surface-to-
surface activities using explosive medium-caliber projectiles.
(C) 1,000 yd around the intended impact location for surface-to-
surface activities using explosive large-caliber projectiles.
(D) Prior to the start of the activity (e.g., when maneuvering on
station), Navy personnel must observe the mitigation zone for marine
mammals; if marine mammals are observed, Navy personnel must relocate
or delay the start of firing.
(E) During the activity, Navy personnel must observe for marine
mammals; if marine mammals are observed, Navy personnel must cease
firing.
(F) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing firing) until one of the following conditions has
been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the
intended impact location; the mitigation zone has been clear from any
additional sightings for 10 min for aircraft-based firing or 30 min for
vessel-based firing; or for activities using mobile targets, the
intended impact location has transited a distance equal to double that
of the mitigation zone size beyond the location of the last sighting.
(G) After completion of the activity (e.g., prior to maneuvering
off station), Navy personnel must, when practical (e.g., when platforms
are not constrained by fuel restrictions or mission-essential follow-on
commitments), observe for marine mammals in the vicinity of where
detonations occurred; if any injured or dead marine mammals are
observed, Navy personnel must follow established incident reporting
procedures. If additional platforms are supporting this activity (e.g.,
providing range clearance), these Navy assets must assist in the visual
observation of the area where detonations occurred.
(9) Explosive missiles and rockets. Aircraft-deployed explosive
missiles and rockets. Mitigation applies to activities using a surface
target.
(i) Number of Lookouts and observation platform. One Lookout must
be positioned in an aircraft. If additional platforms are participating
in the activity, Navy personnel positioned in those assets (e.g.,
safety observers, evaluators) must support observing the mitigation
zone for applicable biological resources while performing their regular
duties.
(ii) Mitigation zone and requirements. (A) 900 yd around the
intended impact location for missiles or rockets with 0.6-20 lb net
explosive weight.
(B) 2,000 yd around the intended impact location for missiles with
21-500 lb net explosive weight.
(C) Prior to the initial start of the activity (e.g., during a fly-
over of the mitigation zone), Navy personnel must observe the
mitigation zone for marine mammals; if marine mammals are observed,
Navy personnel must relocate or delay the start of firing.
(D) During the activity, Navy personnel must observe for marine
mammals; if marine mammals are observed, Navy personnel must cease
firing.
(E) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing
[[Page 5896]]
firing) until one of the following conditions has been met: The animal
is observed exiting the mitigation zone; the animal is thought to have
exited the mitigation zone based on a determination of its course,
speed, and movement relative to the intended impact location; or the
mitigation zone has been clear from any additional sightings for 10 min
when the activity involves aircraft that have fuel constraints, or 30
min when the activity involves aircraft that are not typically fuel
constrained.
(F) After completion of the activity (e.g., prior to maneuvering
off station), Navy personnel must, when practical (e.g., when platforms
are not constrained by fuel restrictions or mission-essential follow-on
commitments), observe for marine mammals in the vicinity of where
detonations occurred; if any injured or dead marine mammals are
observed, Navy personnel must follow established incident reporting
procedures. If additional platforms are supporting this activity (e.g.,
providing range clearance), these Navy assets will assist in the visual
observation of the area where detonations occurred.
(10) Explosive bombs--(i) Number of Lookouts and observation
platform. One Lookout must be positioned in an aircraft conducting the
activity. If additional platforms are participating in the activity,
Navy personnel positioned in those assets (e.g., safety observers,
evaluators) must support observing the mitigation zone for applicable
biological resources while performing their regular duties.
(ii) Mitigation zone and requirements. (A) 2,500 yd around the
intended target.
(B) Prior to the initial start of the activity (e.g., when arriving
on station), Navy personnel must observe the mitigation zone for marine
mammals; if marine mammals are observed, Navy personnel must relocate
or delay the start of bomb deployment.
(C) During the activity (e.g., during target approach), Navy
personnel must observe the mitigation zone for marine mammals; if
marine mammals are observed, Navy personnel must cease bomb deployment.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing bomb deployment) until one of the following
conditions has been met: The animal is observed exiting the mitigation
zone; the animal is thought to have exited the mitigation zone based on
a determination of its course, speed, and movement relative to the
intended target; the mitigation zone has been clear from any additional
sightings for 10 min; or for activities using mobile targets, the
intended target has transited a distance equal to double that of the
mitigation zone size beyond the location of the last sighting.
(E) After completion of the activity (e.g., prior to maneuvering
off station), Navy personnel must, when practical (e.g., when platforms
are not constrained by fuel restrictions or mission-essential follow-on
commitments), observe for marine mammals in the vicinity of where
detonations occurred; if any injured or dead marine mammals are
observed, Navy personnel must follow established incident reporting
procedures. If additional platforms are supporting this activity (e.g.,
providing range clearance), these Navy assets must assist in the visual
observation of the area where detonations occurred.
(11) Sinking exercises--(i) Number of Lookouts and observation
platform. Two Lookouts (one must be positioned in an aircraft and one
must be positioned on a vessel). If additional platforms are
participating in the activity, Navy personnel positioned in those
assets (e.g., safety observers, evaluators) must support observing the
mitigation zone for applicable biological resources while performing
their regular duties.
(ii) Mitigation zone and requirements. (A) 2.5 NM around the target
ship hulk.
(B) Prior to the initial start of the activity (90 min prior to the
first firing), Navy personnel must conduct aerial observations of the
mitigation zone for marine mammals; if marine mammals are observed,
Navy personnel must delay the start of firing.
(C) During the activity, Navy personnel must conduct passive
acoustic monitoring for marine mammals and use the information from
detections to assist visual observations. Navy personnel must visually
observe the mitigation zone for marine mammals from the vessel; if
marine mammals are observed, Navy personnel must cease firing.
Immediately after any planned or unplanned breaks in weapons firing of
longer than two hours, Navy personnel must observe the mitigation zone
for marine mammals from the aircraft and vessel; if marine mammals are
observed, Navy personnel must delay recommencement of firing.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing firing) until one of the following conditions has
been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the target
ship hulk; or the mitigation zone has been clear from any additional
sightings for 30 min.
(E) After completion of the activity (for two hours after sinking
the vessel or until sunset, whichever comes first), Navy personnel must
observe for marine mammals in the vicinity of where detonations
occurred; if any injured or dead marine mammals are observed, Navy
personnel must follow established incident reporting procedures. If
additional platforms are supporting this activity (e.g., providing
range clearance), these Navy assets will assist in the visual
observation of the area where detonations occurred.
(12) Explosive mine countermeasure and neutralization activities--
(i) Number of Lookouts and observation platform. (A) One Lookout must
be positioned on a vessel or in an aircraft.
(B) If additional platforms are participating in the activity, Navy
personnel positioned in those assets (e.g., safety observers,
evaluators) must support observing the mitigation zone for applicable
biological resources while performing their regular duties.
(ii) Mitigation zone and requirements. (A) 600 yd around the
detonation site.
(B) Prior to the initial start of the activity (e.g., when
maneuvering on station; typically, 10 min when the activity involves
aircraft that have fuel constraints, or 30 min when the activity
involves aircraft that are not typically fuel constrained), Navy
personnel must observe the mitigation zone for marine mammals; if
marine mammals are observed, Navy personnel must relocate or delay the
start of detonations.
(C) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must cease detonations.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing detonations) until one of the following conditions
has been met: The animal is observed exiting the mitigation zone;
[[Page 5897]]
the animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to detonation
site; or the mitigation zone has been clear from any additional
sightings for 10 min when the activity involves aircraft that have fuel
constraints, or 30 min when the activity involves aircraft that are not
typically fuel constrained.
(F) After completion of the activity (typically 10 min when the
activity involves aircraft that have fuel constraints, or 30 min when
the activity involves aircraft that are not typically fuel
constrained), Navy personnel must observe for marine mammals in the
vicinity of where detonations occurred; if any injured or dead marine
mammals are observed, Navy personnel must follow established incident
reporting procedures. If additional platforms are supporting this
activity (e.g., providing range clearance), these Navy assets must
assist in the visual observation of the area where detonations
occurred.
(13) Explosive mine neutralization activities involving Navy
divers--(i) Number of Lookouts and observation platform. (A) Two
Lookouts (two small boats with one Lookout each, or one Lookout must be
on a small boat and one must be in a rotary-wing aircraft) when
implementing the smaller mitigation zone.
(B) Four Lookouts (two small boats with two Lookouts each), and a
pilot or member of an aircrew must serve as an additional Lookout if
aircraft are used during the activity, when implementing the larger
mitigation zone.
(C) All divers placing the charges on mines will support the
Lookouts while performing their regular duties and will report
applicable sightings to their supporting small boat or Range Safety
Officer.
(D) If additional platforms are participating in the activity, Navy
personnel positioned in those assets (e.g., safety observers,
evaluators) must support observing the mitigation zone for applicable
biological resources while performing their regular duties.
(ii) Mitigation zone and requirements. (A) 500 yd around the
detonation site during activities under positive control using.
(B) 1,000 yd around the detonation site during all activities using
time-delay fuses.
(C) Prior to the initial start of the activity (e.g., when
maneuvering on station for activities under positive control; 30 min
for activities using time-delay firing devices), Navy personnel must
observe the mitigation zone for marine mammals; if marine mammals are
observed, Navy personnel must relocate or delay the start of
detonations or fuse initiation.
(D) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must cease detonations or fuse initiation. To the maximum extent
practicable depending on mission requirements, safety, and
environmental conditions, Navy personnel must position boats near the
mid-point of the mitigation zone radius (but outside of the detonation
plume and human safety zone), must position themselves on opposite
sides of the detonation location (when two boats are used), and must
travel in a circular pattern around the detonation location with one
Lookout observing inward toward the detonation site and the other
observing outward toward the perimeter of the mitigation zone. If used,
Navy aircraft must travel in a circular pattern around the detonation
location to the maximum extent practicable. Navy personnel must not set
time-delay firing devices to exceed 10 min.
(E) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted animal to leave the mitigation zone prior to the initial start
of the activity (by delaying the start) or during the activity (by not
recommencing detonations) until one of the following conditions has
been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the
detonation site; or the mitigation zone has been clear from any
additional sightings for 10 min during activities under positive
control with aircraft that have fuel constraints, or 30 min during
activities under positive control with aircraft that are not typically
fuel constrained and during activities using time-delay firing devices.
(F) After completion of an activity, the Navy must observe for
marine mammals for 30 min. Navy personnel must observe for marine
mammals in the vicinity of where detonations occurred; if any injured
or dead marine mammals are observed, Navy personnel must follow
established incident reporting procedures. If additional platforms are
supporting this activity (e.g., providing range clearance), these Navy
assets must assist in the visual observation of the area where
detonations occurred.
(14) Maritime security operations--anti-swimmer grenades--(i)
Number of Lookouts and observation platform. One Lookout must be
positioned on the small boat conducting the activity. If additional
platforms are participating in the activity, Navy personnel positioned
in those assets (e.g., safety observers, evaluators) must support
observing the mitigation zone for applicable biological resources while
performing their regular duties.
(ii) Mitigation zone and requirements. (A) 200 yd around the
intended detonation location.
(B) Prior to the initial start of the activity (e.g., when
maneuvering on station), Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must relocate or delay the start of detonations.
(C) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must cease detonations.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing detonations) until one of the following conditions
has been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the
intended detonation location; the mitigation zone has been clear from
any additional sightings for 30 min; or the intended detonation
location has transited a distance equal to double that of the
mitigation zone size beyond the location of the last sighting.
(E) After completion of the activity (e.g., prior to maneuvering
off station), Navy personnel must, when practical (e.g., when platforms
are not constrained by fuel restrictions or mission-essential follow-on
commitments), observe for marine mammals in the vicinity of where
detonations occurred; if any injured or dead marine mammals are
observed, Navy personnel must follow established incident reporting
procedures. If additional platforms are supporting this activity (e.g.,
providing range clearance), these Navy assets will assist in the visual
observation of the area where detonations occurred.
(15) Vessel movement. The mitigation will not be applied if: The
vessel's safety is threatened; the vessel is restricted in its ability
to maneuver (e.g., during launching and recovery of aircraft or landing
craft, during towing activities, when mooring); the vessel is
[[Page 5898]]
operated autonomously; or when impracticable based on mission
requirements (e.g., during Amphibious Assault and Amphibious Raid
exercises).
(i) Number of Lookouts and observation platform. One Lookout must
be on the vessel that is underway.
(ii) Mitigation zone and requirements. (A) 500 yd around whales.
(B) 200 yd around all other marine mammals (except bow-riding
dolphins).
(C) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must maneuver to maintain distance.
(iv) Incident reporting procedures. If a marine mammal vessel
strike occurs, Navy personnel must follow the established incident
reporting procedures.
(16) Towed in-water devices. Mitigation applies to devices that are
towed from a manned surface platform or manned aircraft. The mitigation
will not be applied if the safety of the towing platform or in-water
device is threatened.
(i) Number of Lookouts and observation platform. One Lookout must
be positioned on a manned towing platform.
(ii) Mitigation zone and requirements. (A) 250 yd around marine
mammals.
(B) During the activity (i.e., when towing an in-water device),
Navy personnel must observe the mitigation zone for marine mammals; if
marine mammals are observed, Navy personnel must maneuver to maintain
distance.
(17) Small-, medium-, and large-caliber non-explosive practice
munitions. Mitigation applies to activities using a surface target.
(i) Number of Lookouts and observation platform. One Lookout must
be positioned on the platform conducting the activity. Depending on the
activity, the Lookout could be the same as the one described for
``Weapons firing noise'' in paragraph (a)(3)(i) of this section.
(ii) Mitigation zone and requirements. (A) 200 yd around the
intended impact location.
(B) Prior to the start of the activity (e.g., when maneuvering on
station), Navy personnel must observe the mitigation zone for marine
mammals; if marine mammals are observed, Navy personnel must relocate
or delay the start of firing.
(C) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must cease firing.
(D) Commencement/recommencement conditions after a marine mammal
sighting before or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing firing) until one of the following conditions has
been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the
intended impact location; the mitigation zone has been clear from any
additional sightings for 10 min for aircraft-based firing or 30 min for
vessel-based firing; or for activities using a mobile target, the
intended impact location has transited a distance equal to double that
of the mitigation zone size beyond the location of the last sighting.
(18) Non-explosive missiles and rockets. Aircraft-deployed non-
explosive missiles and rockets. Mitigation applies to activities using
a surface target.
(i) Number of Lookouts and observation platform. One Lookout must
be positioned in an aircraft.
(ii) Mitigation zone and requirements. (A) 900 yd around the
intended impact location.
(B) Prior to the initial start of the activity (e.g., during a fly-
over of the mitigation zone), Navy personnel must observe the
mitigation zone for marine mammals; if marine mammals are observed,
Navy personnel must relocate or delay the start of firing.
(C) During the activity, Navy personnel must observe the mitigation
zone for marine mammals; if marine mammals are observed, Navy personnel
must cease firing.
(D) Commencement/recommencement conditions after a marine mammal
sighting prior to or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing firing) until one of the following conditions has
been met: The animal is observed exiting the mitigation zone; the
animal is thought to have exited the mitigation zone based on a
determination of its course, speed, and movement relative to the
intended impact location; or the mitigation zone has been clear from
any additional sightings for 10 min when the activity involves aircraft
that have fuel constraints, or 30 min when the activity involves
aircraft that are not typically fuel constrained.
(19) Non-explosive bombs and mine shapes. Non-explosive bombs and
non-explosive mine shapes during mine laying activities.
(i) Number of Lookouts and observation platform. One Lookout must
be positioned in an aircraft.
(ii) Mitigation zone and requirements. (A) 1,000 yd around the
intended target.
(B) Prior to the initial start of the activity (e.g., when arriving
on station), Navy personnel must observe the mitigation zone for marine
mammals; if marine mammals are observed, Navy personnel must relocate
or delay the start of bomb deployment or mine laying.
(C) During the activity (e.g., during approach of the target or
intended minefield location), Navy personnel must observe the
mitigation zone for marine mammals and, if marine mammals are observed,
Navy personnel must cease bomb deployment or mine laying.
(D) Commencement/recommencement conditions after a marine mammal
sighting prior to or during the activity. Navy personnel must allow a
sighted marine mammal to leave the mitigation zone prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing bomb deployment or mine laying) until one of the
following conditions has been met: The animal is observed exiting the
mitigation zone; the animal is thought to have exited the mitigation
zone based on a determination of its course, speed, and movement
relative to the intended target or minefield location; the mitigation
zone has been clear from any additional sightings for 10 min; or for
activities using mobile targets, the intended target has transited a
distance equal to double that of the mitigation zone size beyond the
location of the last sighting.
(b) Mitigation areas. In addition to procedural mitigation, Navy
personnel must implement mitigation measures within mitigation areas to
avoid or reduce potential impacts on marine mammals.
(1) Mitigation areas for marine mammals off Saipan in MITT Study
Area for sonar, explosives, and vessel strikes--(i) Mitigation area
requirements--(A) Marpi Reef Geographic Mitigation Area. (1) Navy
personnel must not use explosives that could potentially result in
takes of marine mammals during training and testing.
(2) The Navy will also report the total hours of MF1 surface ship
hull-mounted mid-frequency active sonar from December through April
used in this
[[Page 5899]]
area in its annual training and testing activity reports submitted to
NMFS.
(3) Should national security require the use of explosives that
could potentially result in the take of marine mammals during training
or testing, Naval units must obtain permission from the appropriate
designated Command authority prior to commencement of the activity.
Navy personnel must provide NMFS with advance notification and include
the information (e.g., explosive usage) in its annual activity reports
submitted to NMFS.
(B) Chalan Kanoa Geographic Mitigation Area. (1) Navy personnel
must not use explosives that could potentially result in takes of
marine mammals during training and testing.
(2) The Navy will also report the total hours of MF1 surface ship
hull-mounted mid-frequency active sonar from December through April
used in this area in its annual training and testing activity reports
submitted to NMFS.
(3) Should national security require the use of explosives that
could potentially result in the take of marine mammals during training
or testing, Naval units must obtain permission from the appropriate
designated Command authority prior to commencement of the activity.
Navy personnel must provide NMFS with advance notification and include
the information (e.g., explosive usage) in its annual activity reports
submitted to NMFS.
(C) Marpi Reef and Chalan Kanoa Reef Awareness Notification Message
Area (December-April). (1) Navy personnel must issue a seasonal
awareness notification message to alert ships and aircraft operating in
the area to the possible presence of concentrations of large whales, or
increased concentrations of humpback whales.
(2) To maintain safety of navigation and to avoid interactions with
large whales during transits, Navy personnel must instruct vessels to
remain vigilant to the presence of large whale species (including
humpback whales) that when concentrated seasonally, may become
vulnerable to vessel strikes.
(3) Platforms must use the information from the awareness
notification message to assist their visual observation of applicable
mitigation zones during training and testing activities and to aid in
the implementation of procedural mitigation.
(ii) [Reserved]
(2) Mitigation areas for marine mammals off Guam of the MITT Study
Area for sonar and explosives--(i) Mitigation area requirements--(A)
Agat Bay Nearshore Geographic Mitigation Area. (1) Navy personnel must
not conduct MF1 surface ship hull-mounted mid-frequency active sonar
year-round.
(2) Should national security require the use of MF1 surface ship
hull-mounted mid-frequency active sonar during training and testing
within the Agat Bay Nearshore Geographic Mitigation Area, Naval units
must obtain permission from the appropriate designated Command
authority prior to commencement of the activity. Navy personnel must
provide NMFS with advance notification and include the information
(e.g., sonar hours) in its annual activity reports submitted to NMFS.
(3) Navy personnel must not use in-water explosives year-round.
(4) Should national security require the use of explosives that
could potentially result in the take of marine mammals during training
or testing within the Agat Bay Nearshore Geographic Mitigation Area,
Naval units must obtain permission from the appropriate designated
Command authority prior to commencement of the activity. Navy personnel
must provide NMFS with advance notification and include the information
(e.g., explosives usage) in its annual activity reports submitted to
NMFS.
(B) [Reserved]
Sec. 218.95 Requirements for monitoring and reporting.
(a) Unauthorized take. Navy personnel must notify NMFS immediately
(or as soon as operational security considerations allow) if the
specified activity identified in Sec. 218.90 is thought to have
resulted in the mortality or serious injury of any marine mammals, or
in any Level A harassment or Level B harassment take of marine mammals
not identified in this subpart.
(b) Monitoring and reporting under the LOA. The Navy must conduct
all monitoring and reporting required under the LOA, including abiding
by the MITT Study Area monitoring program. Details on program goals,
objectives, project selection process, and current projects are
available at www.navymarinespeciesmonitoring.us.
(c) Notification of injured, live stranded, or dead marine mammals.
The Navy must consult the Notification and Reporting Plan, which sets
out notification, reporting, and other requirements when dead, injured,
or live stranded marine mammals are detected. The Notification and
Reporting Plan is available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
(d) Annual MITT Study Area marine species monitoring report. The
Navy must submit an annual report of the MITT Study Area monitoring
describing the implementation and results from the previous calendar
year. Data collection methods must be standardized across range
complexes and study areas to allow for comparison in different
geographic locations. The report must be submitted to the Director,
Office of Protected Resources, NMFS, either within three months after
the end of the calendar year, or within three months after the
conclusion of the monitoring year, to be determined by the Adaptive
Management process. This report will describe progress of knowledge
made with respect to intermediate scientific objectives within the MITT
Study Area associated with the Integrated Comprehensive Monitoring
Program (ICMP). Similar study questions must be treated together so
that progress on each topic can be summarized across all Navy ranges.
The report need not include analyses and content that does not provide
direct assessment of cumulative progress on the monitoring plan study
questions. As an alternative, the Navy may submit a multi-range complex
annual monitoring plan report to fulfill this requirement. Such a
report will describe progress of knowledge made with respect to
monitoring study questions across multiple Navy ranges associated with
the ICMP. Similar study questions must be treated together so that
progress on each topic can be summarized across multiple Navy ranges.
The report need not include analyses and content that does not provide
direct assessment of cumulative progress on the monitoring study
question. This will continue to allow the Navy to provide a cohesive
monitoring report covering multiple ranges (as per ICMP goals), rather
than entirely separate reports for the MITT, Hawaii-Southern
California, Gulf of Alaska, and Northwest Study Areas.
(e) Annual MITT Study Area training exercise report and testing
activity reports. Each year, the Navy must submit two preliminary
reports (Quick Look Report) detailing the status of authorized sound
sources within 21 days after the anniversary of the date of issuance of
the LOA to the Director, Office of Protected Resources, NMFS. Each
year, the Navy must submit a detailed report to the Director, Office of
Protected Resources, NMFS, within three months after the one-year
anniversary of the date of issuance of the LOA. The MITT Annual
Training Exercise Report and Testing Activity
[[Page 5900]]
Report can be consolidated with other exercise reports from other range
complexes in the Pacific Ocean for a single Pacific Exercise Report, if
desired. The annual report must contain information on the total hours
of operation of MFI surface ship hull-mounted mid-frequency active
sonar used in the Marpi Reef and Chalan Kanoa Reef Geographic
Mitigation Areas, major training exercises (MTEs), Sinking Exercise
(SINKEX) events, and a summary of all sound sources used, including
within specific mitigation reporting areas as described in paragraph
(e)(3) of this section. The analysis in the detailed report must be
based on the accumulation of data from the current year's report and
data collected from previous annual reports. The annual report will
also contain cumulative sonar and explosive use quantity from previous
years' reports through the current year. Additionally, if there were
any changes to the sound source allowance in a given year, or
cumulatively, the report would include a discussion of why the change
was made and include analysis to support how the change did or did not
affect the analysis in the MITT EIS/OEIS and MMPA final rule. The
annual report would also include the details regarding specific
requirements associated with specific mitigation areas. The analysis in
the detailed report would be based on the accumulation of data from the
current year's report and data collected from previous reports. The
final annual/close-out report at the conclusion of the authorization
period (year seven) would also serve as the comprehensive close-out
report and include both the final year annual use compared to annual
authorization as well as a cumulative seven-year annual use compared to
seven-year authorization. The detailed reports must contain information
identified in paragraphs (e)(1) through (6) of this section.
(1) MTEs. This section of the report must contain the following
information for MTEs conducted in the MITT Study Area.
(i) Exercise Information for each MTE.
(A) Exercise designator.
(B) Date that exercise began and ended.
(C) Location.
(D) Number and types of active sonar sources used in the exercise.
(E) Number and types of passive acoustic sources used in exercise.
(F) Number and types of vessels, aircraft, and other platforms
participating in exercise.
(G) Total hours of all active sonar source operation.
(H) Total hours of each active sonar source bin.
(I) Wave height (high, low, and average) during exercise.
(ii) Individual marine mammal sighting information for each
sighting in each exercise where mitigation was implemented:
(A) Date/Time/Location of sighting.
(B) Species (if not possible, indication of whale or dolphin).
(C) Number of individuals.
(D) Initial Detection Sensor (e.g., sonar, Lookout).
(E) Indication of specific type of platform observation was made
from (including, for example, what type of surface vessel or testing
platform).
(F) Length of time observers maintained visual contact with marine
mammal.
(G) Sea state.
(H) Visibility.
(I) Sound source in use at the time of sighting.
(J) Indication of whether animal was less than 200 yd, 200 to 500
yd, 500 to 1,000 yd, 1,000 to 2,000 yd, or greater than 2,000 yd from
sonar source.
(K) Whether operation of sonar sensor was delayed, or sonar was
powered or shut down, and how long the delay.
(L) If source in use was hull-mounted, true bearing of animal from
the vessel, true direction of vessel's travel, and estimation of
animal's motion relative to vessel (opening, closing, parallel).
(M) Lookouts must report, in plain language and without trying to
categorize in any way, the observed behavior of the animal(s) (such as
animal closing to bow ride, paralleling course/speed, floating on
surface and not swimming, etc.) and if any calves were present.
(iii) An evaluation (based on data gathered during all of the MTEs)
of the effectiveness of mitigation measures designed to minimize the
received level to which marine mammals may be exposed. This evaluation
must identify the specific observations that support any conclusions
the Navy reaches about the effectiveness of the mitigation.
(2) SINKEXs. This section of the report must include the following
information for each SINKEX completed that year.
(i) Exercise information gathered for each SINKEX.
(A) Location.
(B) Date and time exercise began and ended.
(C) Total hours of observation by Lookouts before, during, and
after exercise.
(D) Total number and types of explosive source bins detonated.
(E) Number and types of passive acoustic sources used in exercise.
(F) Total hours of passive acoustic search time.
(G) Number and types of vessels, aircraft, and other platforms,
participating in exercise.
(H) Wave height in feet (high, low, and average) during exercise.
(I) Narrative description of sensors and platforms utilized for
marine mammal detection and timeline illustrating how marine mammal
detection was conducted.
(ii) Individual marine mammal observation (by Navy Lookouts)
information for each sighting where mitigation was implemented.
(A) Date/Time/Location of sighting.
(B) Species (if not possible, indicate whale or dolphin).
(C) Number of individuals.
(D) Initial detection sensor (e.g., sonar or Lookout).
(E) Length of time observers maintained visual contact with marine
mammal.
(F) Sea state.
(G) Visibility.
(H) Whether sighting was before, during, or after detonations/
exercise, and how many minutes before or after.
(I) Distance of marine mammal from actual detonations (or target
spot if not yet detonated): Less than 200 yd, 200 to 500 yd, 500 to
1,000 yd, 1,000 to 2,000 yd, or greater than 2,000 yd.
(J) Lookouts must report, in plain language and without trying to
categorize in any way, the observed behavior of the animal(s) (such as
animal closing to bow ride, paralleling course/speed, floating on
surface and not swimming etc.), including speed and direction and if
any calves were present.
(K) The report must indicate whether explosive detonations were
delayed, ceased, modified, or not modified due to marine mammal
presence and for how long.
(L) If observation occurred while explosives were detonating in the
water, indicate munition type in use at time of marine mammal
detection.
(3) Summary of sources used. This section of the report must
include the following information summarized from the authorized sound
sources used in all training and testing events:
(i) Total annual hours or quantity (per the LOA) of each bin of
sonar or other transducers and
(ii) Total annual expended/detonated ordinance (missiles, bombs,
sonobuoys, etc.) for each explosive bin.
(4) MITT Study Area Mitigation Areas. The Navy must report any use
that occurred as specifically described in these areas. Information
included in the classified annual reports may be
[[Page 5901]]
used to inform future adaptive management of activities within the MITT
Study Area.
(5) Geographic information presentation. The reports must present
an annual (and seasonal, where practical) depiction of training and
testing bin usage geographically across the MITT Study Area.
(6) Sonar exercise notification. The Navy must submit to NMFS
(contact as specified in the LOA) an electronic report within fifteen
calendar days after the completion of any MTE indicating: (i) Location
of the exercise; (ii) Beginning and end dates of the exercise; and
(iii) Type of exercise.
(f) Seven-year annual/close-out report. The final (year seven)
draft annual/close-out report must be submitted within three months
after the expiration of this subpart to the Director, Office of
Protected Resources, NMFS. NMFS must submit comments on the draft
close-out report, if any, within three months of receipt. The report
will be considered final after the Navy has addressed NMFS' comments,
or three months after the submittal of the draft if NMFS does not
provide comments.
Sec. 218.96 Letters of Authorization.
(a) To incidentally take marine mammals pursuant to the regulations
in this subpart, the Navy must apply for and obtain an LOA in
accordance with Sec. 216.106 of this chapter.
(b) An LOA, unless suspended or revoked, may be effective for a
period of time not to exceed August 3, 2027.
(c) If an LOA expires prior to August 3, 2027, the Navy may apply
for and obtain a renewal of the LOA.
(d) In the event of projected changes to the activity or to
mitigation, monitoring, or reporting (excluding changes made pursuant
to the adaptive management provision of Sec. 218.97(c)(1)) required by
an LOA issued under this subpart, the Navy must apply for and obtain a
modification of the LOA as described in Sec. 218.97.
(e) Each LOA will set forth:
(1) Permissible methods of incidental taking;
(2) Geographic areas for incidental taking;
(3) Means of effecting the least practicable adverse impact (i.e.,
mitigation) on the species or stocks of marine mammals and their
habitat; and
(4) Requirements for monitoring and reporting.
(f) Issuance of the LOA(s) must be based on a determination that
the level of taking is consistent with the findings made for the total
taking allowable under the regulations in this subpart.
(g) Notice of issuance or denial of the LOA(s) will be published in
the Federal Register within 30 days of a determination.
Sec. 218.97 Renewals and modifications of Letters of Authorization.
(a) An LOA issued under Sec. Sec. 216.106 of this chapter and
218.96 for the activity identified in Sec. 218.90(c) may be renewed or
modified upon request by the applicant, provided that:
(1) The planned specified activity and mitigation, monitoring, and
reporting measures, as well as the anticipated impacts, are the same as
those described and analyzed for the regulations in this subpart
(excluding changes made pursuant to the adaptive management provision
in paragraph (c)(1) of this section); and
(2) NMFS determines that the mitigation, monitoring, and reporting
measures required by the previous LOA(s) were implemented.
(b) For LOA modification or renewal requests by the applicant that
include changes to the activity or to the mitigation, monitoring, or
reporting measures (excluding changes made pursuant to the adaptive
management provision in paragraph (c)(1) of this section) that do not
change the findings made for the regulations or result in no more than
a minor change in the total estimated number of takes (or distribution
by species or stock or years), NMFS may publish a notice of planned LOA
in the Federal Register, including the associated analysis of the
change, and solicit public comment before issuing the LOA.
(c) An LOA issued under Sec. Sec. 216.106 of this chapter and
218.96 may be modified by NMFS under the following circumstances:
(1) Adaptive management. After consulting with the Navy regarding
the practicability of the modifications, NMFS may modify (including
adding or removing measures) the existing mitigation, monitoring, or
reporting measures if doing so creates a reasonable likelihood of more
effectively accomplishing the goals of the mitigation and monitoring.
(i) Possible sources of data that could contribute to the decision
to modify the mitigation, monitoring, or reporting measures in an LOA
include:
(A) Results from the Navy's monitoring from the previous year(s);
(B) Results from other marine mammal and/or sound research or
studies; or
(C) Any information that reveals marine mammals may have been taken
in a manner, extent, or number not authorized by the regulations in
this subpart or subsequent LOAs.
(ii) If, through adaptive management, the modifications to the
mitigation, monitoring, or reporting measures are substantial, NMFS
will publish a notice of planned LOA in the Federal Register and
solicit public comment.
(2) Emergencies. If NMFS determines that an emergency exists that
poses a significant risk to the well-being of the species or stocks of
marine mammals specified in LOAs issued pursuant to Sec. Sec. 216.106
of this chapter and 218.96, an LOA may be modified without prior notice
or opportunity for public comment. Notice would be published in the
Federal Register within thirty days of the action.
Sec. 218.98 [Reserved]
[FR Doc. 2020-00481 Filed 1-30-20; 8:45 am]
BILLING CODE 3510-22-P