[Federal Register Volume 85, Number 102 (Wednesday, May 27, 2020)]
[Notices]
[Pages 31856-31882]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-11203]
[[Page 31855]]
Vol. 85
Wednesday,
No. 102
May 27, 2020
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to Site Characterization Surveys Off the
Coast of Massachusetts; Notice
Federal Register / Vol. 85, No. 102 / Wednesday, May 27, 2020 /
Notices
[[Page 31856]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XA065]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Site Characterization Surveys Off
the Coast of Massachusetts
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from Mayflower Wind Energy LLC
(Mayflower) for authorization to take marine mammals incidental to site
characterization surveys off the coast of Massachusetts in the area of
the Commercial Lease of Submerged Lands for Renewable Energy
Development on the Outer Continental Shelf (OCS-A 0521) and along a
potential submarine cable route to landfall at Falmouth, Massachusetts.
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting
comments on its proposal to issue an incidental harassment
authorization (IHA) to incidentally take marine mammals during the
specified activities. NMFS is also requesting comments on a possible
one-year renewal that could be issued under certain circumstances and
if all requirements are met, as described in Request for Public
Comments at the end of this notice. NMFS will consider public comments
prior to making any final decision on the issuance of the requested
MMPA authorizations and agency responses will be summarized in the
final notice of our decision.
DATES: Comments and information must be received no later than June 26,
2020.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service. Physical comments should be sent to
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments
should be sent to [email protected].
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments received electronically, including
all attachments, must not exceed a 25-megabyte file size. Attachments
to electronic comments will be accepted in Microsoft Word or Excel or
Adobe PDF file formats only. All comments received are a part of the
public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Amy Fowler, Office of Protected
Resources, NMFS, (301) 427-8401. Electronic copies of the application
and supporting documents, as well as a list of the references cited in
this document, may be obtained online at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these
documents, please call the contact listed above.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) 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, a notice of a
proposed incidental take authorization may be provided to the public
for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) 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 the species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the mitigation,
monitoring and reporting of the takings are set forth.
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 review our proposed action (i.e., the issuance of an
incidental harassment authorization) with respect to potential impacts
on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (incidental harassment authorizations with
no anticipated serious injury or mortality) of the Companion Manual for
NOAA Administrative Order 216-6A, which do not individually or
cumulatively have the potential for significant impacts on the quality
of the human environment and for which we have not identified any
extraordinary circumstances that would preclude this categorical
exclusion. Accordingly, NMFS has preliminarily determined that the
issuance of the proposed IHA qualifies to be categorically excluded
from further NEPA review.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
IHA request.
Summary of Request
On January 17, 2020, NMFS received a request from Mayflower for an
IHA to take marine mammals incidental to site characterization surveys
in the area of the Commercial Lease of Submerged Lands for Renewable
Energy Development on the Outer Continental Shelf (OCS-A 0521; Lease
Area) and a submarine export cable route connecting the Lease Area to
landfall in Falmouth, Massachusetts. A revised application was received
on April 9, 2020. NMFS deemed that request to be adequate and complete.
Mayflower's request is for take of a small number of 14 species of
marine mammals by Level B harassment only. Neither Mayflower nor NMFS
expects serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
Description of Proposed Activity
Overview
Mayflower proposes to conduct marine site characterization surveys,
including high-resolution geophysical (HRG) and geotechnical surveys,
in the area of Commercial Lease of Submerged Lands for Renewable Energy
Development on the Outer Continental
[[Page 31857]]
Shelf #OCS-A 0521 (Lease Area) and along a potential submarine cable
route to landfall at Falmouth, Massachusetts.
The purpose of the proposed surveys is to acquire geotechnical and
HRG data on the bathymetry, seafloor morphology, subsurface geology,
environmental/biological sites, seafloor obstructions, soil conditions,
and locations of any man-made, historical, or archaeological resources
within the Lease Area and export cable route to support development of
offshore wind energy facilities. Up to three survey vessels may operate
concurrently as part of the proposed surveys, but the three vessels
will spend no more than a combined total of 215 days at sea. Underwater
sound resulting from Mayflower's proposed site characterization surveys
has the potential to result in incidental take of marine mammals in the
form of behavioral harassment.
Dates and Duration
The total duration of geophysical survey activities would be
approximately 215 survey-days. This schedule is based on 24-hour
operations in the offshore, deep-water portion of the Lease Area, and
12-hour operations in shallow-water and nearshore areas of the export
cable route. The surveys are expected to occur between June and
September 2020.
Specific Geographic Region
Mayflower's survey activities would occur in the Northwest Atlantic
Ocean approximately 60 kilometers (km) south of Martha's Vineyard,
Massachusetts. All survey effort would occur within U.S. Federal and
state waters. Surveys would occur within the Lease Area and along a
potential submarine cable route connecting the Lease Area and landfall
at Falmouth, Massachusetts (see Figure 1 in Mayflower's IHA
application).
Detailed Description of Specific Activity
Mayflower's proposed marine site characterization surveys include
HRG and geotechnical survey activities. These survey activities would
occur within the Lease Area and within an export cable route between
the Lease Area and Falmouth, Massachusetts. The Lease Area is
approximately 515.5 square kilometers (km\2\; 127,388 acres) and lies
approximately 20 nautical miles (38 km south-southwest of Nantucket.
Water depths in the Lease Area are approximately 38-62 meters (m). For
the purpose of this IHA the Lease Area and export cable route are
collectively referred to as the Project Area.
The proposed HRG and geotechnical survey activities are described
below.
Geotechnical Survey Activities
Mayflower's proposed geotechnical survey activities would include
the following:
Sample boreholes and vibracores to determine geological
and geotechnical characteristics of sediments; and
Seabed core penetration tests (CPTs) to determine
stratigraphy and in situ conditions of the sub-surface sediments.
Geotechnical investigation activities are anticipated to be
conducted from up to two vessels, each equipped with dynamic
positioning (DP) thrusters. Impacts to the seafloor from this equipment
will be limited to the minimal contact of the sampling equipment, and
inserted boring and probes.
In considering whether marine mammal harassment is an expected
outcome of exposure to a particular activity or sound source, NMFS
considers the nature of the exposure itself (e.g., the magnitude,
frequency, or duration of exposure), characteristics of the marine
mammals potentially exposed, and the conditions specific to the
geographic area where the activity is expected to occur (e.g., whether
the activity is planned in a foraging area, breeding area, nursery or
pupping area, or other biologically important area for the species). We
then consider the expected response of the exposed animal and whether
the nature and duration or intensity of that response is expected to
cause disruption of behavioral patterns (e.g., migration, breathing,
nursing, breeding, feeding, or sheltering) or injury.
Geotechnical survey activities would be conducted from drill ships
equipped with DP thrusters. DP thrusters would be used to position the
sampling vessel on station and maintain position at each sampling
location during the sampling activity. Sound produced through use of DP
thrusters is similar to that produced by transiting vessels and DP
thrusters are typically operated either in a similarly predictable
manner or used for short durations around stationary activities. NMFS
does not believe acoustic impacts from DP thrusters are likely to
result in take of marine mammals in the absence of activity- or
location-specific circumstances that may otherwise represent specific
concerns for marine mammals (i.e., activities proposed in area known to
be of particular importance for a particular species), or associated
activities that may increase the potential to result in take when in
concert with DP thrusters. In this case, we are not aware of any such
circumstances. Therefore, NMFS believes the likelihood of DP thrusters
used during the proposed geotechnical surveys resulting in harassment
of marine mammals to be so low as to be discountable. As DP thrusters
are not expected to result in take of marine mammals, these activities
are not analyzed further in this document.
Field studies conducted off the coast of Virginia to determine the
underwater noise produced by CPTs and borehole drilling found that
these activities did not result in underwater noise levels that
exceeded current thresholds for Level B harassment of marine mammals
(Kalapinski, 2015). Given the small size and energy footprint of CPTs
and boring cores, NMFS believes the likelihood that noise from these
activities would exceed the Level B harassment threshold at any
appreciable distance is so low as to be discountable. Therefore,
geotechnical survey activities, including CPTs, vibracores, and
borehole drilling, are not expected to result in harassment of marine
mammals and are not analyzed further in this document.
Geophysical Survey Activities
Mayflower has proposed that HRG survey activities would be
conducted continuously 24 hours per day in the deep-water portion of
the Project Area, and 12 hours per day in the shallow-water portion of
the survey area. Based on this operation schedule, the estimated total
duration of the proposed activities would be a combined total of 215
survey days. This includes 90 days of surveys in the Lease Area and
deep-water section of the export cable route, 95 days in the shallow-
water section of the cable route, and 30 days in the very shallow
section of the cable route (waters less than 5 m deep) (see Table 1).
These estimated durations include potential weather down time.
Table 1--Summary of Proposed HRG Survey Segments
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Duration
Survey area Operating schedule (survey days)
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Lease Area and deep-water section 24 hours/day........ 90
of cable route.
[[Page 31858]]
Shallow-water section of cable 12 hours/day 95
route. (daylight only).
Very shallow cable route.......... 12 hours/day 30
(daylight only).
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All areas combined............ .................... 215
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The HRG survey activities will be supported by vessels of
sufficient size to accomplish the survey goals in each of the specified
survey areas. Surveys in each of the identified survey areas will be
executed by a single vessel during any given campaign (i.e., no more
than one survey vessel would operate in the Lease Area and deep-water
section of the cable route at any given time, but there may be one
survey vessel operating in the Lease Area and deep-water cable route,
one vessel in the shallow-water section of the cable route, and one
vessel in the very shallow waters of the cable route operating
concurrently, for a total of three vessels conducting HRG surveys). HRG
equipment will either by mounted to or towed behind the survey vessel
at a typical survey speed of approximately 3 knots (kn; 5.6 km per
hour). The geophysical survey activities proposed by Mayflower would
include the following:
Seafloor imaging (sidescan sonar) for seabed sediment
classification purposes, to identify natural and man-made acoustic
targets resting on the seafloor. The sonar device emits conical or fan-
shaped pulses down toward the seafloor in multiple beams at a wide
angle, perpendicular to the path of the sensor through the water. The
acoustic return of the pulses is recorded in a series of cross-track
slices, which can be joined to form an image of the sea bottom within
the swath of the beam. They are typically towed beside or behind the
vessel or from an autonomous vehicle;
Multibeam echosounder (MBES) to determine water depths and
general bottom topography. MBES sonar systems project sonar pulses in
several angled beams from a transducer mounted to a ship's hull. The
beams radiate out from the transducer in a fan-shaped pattern
orthogonally to the ship's direction;
Medium penetration sub-bottom profiler (sparkers) to map
deeper subsurface stratigraphy as needed. Sparkers create acoustic
pulses from 50 Hz to 4 kHz omni-directionally from the source that can
penetrate several hundred meters into the seafloor. Typically towed
behind the vessel with adjacent hydrophone arrays to receive the return
signals;
Parametric sub-bottom profiler to provide high data
density in sub-bottom profiles that are typically required for cable
routes, very shallow water, and archaeological surveys. Typically
mounted on the hull of the vessel or from a side pole; and
Ultra-short baseline (USBL) positioning and Global
Acoustic Positioning System (GAPS) to provide high accuracy ranges by
measuring the time between the acoustic pulses transmitted by the
vessel transceiver and the equipment transponder necessary to produce
the acoustic profile. It is a two-component system with a hull or pole
mounted transceiver and one to several transponders either on the
seabed or on the equipment.
Table 2 identifies the representative survey equipment that may be
used in support of planned geophysical survey activities that operate
below 180 kilohertz (kHz) and have the potential to cause acoustic
harassment to marine mammals. The make and model of the listed
geophysical equipment may vary depending on availability and the final
equipment choices will vary depending upon the final survey design,
vessel availability, and survey contractor selection. Geophysical
surveys are expected to use several equipment types concurrently in
order to collect multiple aspects of geophysical data along one
transect. Selection of equipment combinations is based on specific
survey objectives.
Table 2--Summary of HRG Survey Equipment Proposed for Use by Mayflower
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Pulse
HRG equipment category Specific HRG equipment Operating frequency Source level Beamwidth Typical pulse repetition
range (kHz) (dB rms) (degrees) duration (ms) rate (Hz)
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Sparker............................ Geomarine Geo-Spark 800 J 0.25 to 5............. 203 180 3.4 2
system.
Sub-bottom profiler................ Edgetech 3100 with SB-2-16S 2 to 16............... 179 65 10 10
towfish.
Innomar SES-2000 Medium-100 85 to 115............. 241 2 2 40
Parametric.
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The deployment of HRG survey equipment, including the equipment
planned for use during Mayflower's proposed activity, produces sound in
the marine environment that has the potential to result in harassment
of marine mammals. Proposed mitigation, monitoring, and reporting
measures are described in detail later in this document (please see
Proposed Mitigation and Proposed Monitoring and Reporting).
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history, of the potentially affected species.
Additional information regarding population trends and threats may be
found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species
(e.g., physical and behavioral descriptions) may be found on NMFS's
[[Page 31859]]
website. (https://www.fisheries.noaa.gov/find-species).
Table 3 lists all species or stocks for which take is expected and
proposed to be authorized for this action, and summarizes information
related to the population or stock, including regulatory status under
the MMPA and ESA and potential biological removal (PBR), where known.
For taxonomy, we follow Committee on Taxonomy (2019). PBR is defined by
the MMPA as the maximum number of animals, not including natural
mortalities, that may be removed from a marine mammal stock while
allowing that stock to reach or maintain its optimum sustainable
population (as described in NMFS's SARs). While no mortality is
anticipated or authorized here, PBR and annual serious injury and
mortality from anthropogenic sources are included here as gross
indicators of the status of the species and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS's stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS's U.S. Atlantic SARs. All values presented in Table 3 are the most
recent available at the time of publication and are available in the
2018 Atlantic and Gulf of Mexico Marine Mammal Stock Assessments (Hayes
et al., 2019a), available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region
or and draft 2019 Atlantic and Gulf of Mexico Marine Mammal Stock
Assessments (Hayes et al. 2019b) available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports.
Table 3--Marine Mammals Known To Occur in the Project Area That May Be Affected by Mayflower's Proposed Activity
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Stock abundance
ESA/MMPA (CV, Nmin, most
Common name Scientific name Stock status; recent abundance Predicted PBR \4\ Annual M/
strategic (Y/ survey) \2\ abundance \3\ SI \4\
N) \1\
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Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Balaenidae:
North Atlantic right whale.. Eubalaena glacialis Western North E/D; Y 428 (0; 418; n/a). 535 (0.45) *...... 0.9 5.56
Atlantic.
Family Balaenopteridae
(rorquals):
Humpback whale.............. Megaptera Gulf of Maine...... -/-; N 1,396 (0; 1,380; 1,637 (0.07) *.... 22 12.15
novaeangliae. See SAR).
Fin whale....................... Balaenoptera Western North E/D; Y 7,418 (0.25; 4,633 (0.08)...... 12 2.35
physalus. Atlantic. 6,029; See SAR).
Sei whale....................... Balaenoptera Nova Scotia........ E/D; Y 6292 (1.015; 717 (0.30) *...... 6.2 1
borealis. 3,098; see SAR)
236.
Minke whale..................... Balaenoptera....... Canadian East Coast -/-; N 24,202 (0.3; 2,112 (0.05) *.... 1189 8
acutorostrata...... 18,902; See SAR).
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Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family Physeteridae:
Sperm whale................. Physeter NA................. E; Y 4349 (0.28;3,451; 5,353 (0.12)...... 6.9 0
macrocephalus. See SAR).
Family Delphinidae:
Long-finned pilot whale..... Globicephala melas. Western North -/-; Y 5,636 (0.63; 18,977 (0.11) \5\. 35 38
Atlantic. 3,464).
Bottlenose dolphin.......... Tursiops spp....... Western North -/-; N 62,851 (0.23; 97,476 (0.06) \5\. 591 28
Atlantic Offshore. 51,914; See SAR).
Common dolphin.............. Delphinus delphis.. Western North -/-; N 172,825 (0.21; 86,098 (0.12)..... 1,452 419
Atlantic. 145,216; See SAR).
Atlantic white-sided dolphin Lagenorhynchus Western North -/-; N 92,233 (0.71; 37,180 (0.07)..... 544 26
acutus. Atlantic. 54,433; See SAR).
Risso's dolphin............. Grampus griseus.... Western North -/-; N 35,493 (0.19; 7,732 (0.09)...... 303 54.3
Atlantic. 30,289; See SAR).
Family Phocoenidae (porpoises):
Harbor porpoise............. Phocoena phocoena.. Gulf of Maine/Bay -/-; N 95,543 (0.31; 45,089 (0.12) *... 851 217
of Fundy. 74,034; See SAR).
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Order Carnivora--Superfamily Pinnipedia
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Family Phocidae (earless seals):
Gray seal \6\............... Halichoerus grypus. Western North -/-; N 27,131 (0.19; N/A............... 1,389 5,688
Atlantic. 23,158, 2016).
Harbor seal................. Phoca vitulina..... Western North -/-; N 75,834 (0.15; N/A............... 345 333
Atlantic. 66,884, 2018).
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\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region/. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable
[[Page 31860]]
\3\ This information represents species- or guild-specific abundance predicted by recent habitat-based cetacean density models (Roberts et al., 2016,
2017, 2018). These models provide the best available scientific information regarding predicted density patterns of cetaceans in the U.S. Atlantic
Ocean, and we provide the corresponding abundance predictions as a point of reference. Total abundance estimates were produced by computing the mean
density of all pixels in the modeled area and multiplying by its area. For those species marked with an asterisk, the available information supported
development of either two or four seasonal models; each model has an associated abundance prediction. Here, we report the maximum predicted abundance.
\4\ Potential biological removal, defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a
marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population size (OSP). Annual M/SI, found in NMFS' SARs,
represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, subsistence hunting, ship
strike). Annual M/SI values often cannot be determined precisely and is in some cases presented as a minimum value. All M/SI values are as presented
in the draft 2019 SARs (Hayes et al., 2019).
\5\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
the habitat-based cetacean density models produced by Roberts et al. (2016, 2017, 2018) are based in part on available observational data which, in
some cases, is limited to genus or guild in terms of taxonomic definition. Roberts et al. (2016, 2017, 2018) produced density models to genus level
for Globicephala spp. and produced a density model for bottlenose dolphins that does not differentiate between offshore and coastal stocks.
\6\ 8 NMFS stock abundance estimate applies to U.S. population only, actual stock abundance is approximately 505,000.
As indicated above, all 14 species (with 14 managed stocks) in
Table 3 temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur, and we have proposed
authorizing it. All species that could potentially occur in the
proposed survey areas are included in Table 4 of the IHA application.
However, the temporal and/or spatial occurrence of several species
listed in Table 4 in the IHA application is such that take of these
species is not expected to occur. The blue whale (Balaenoptera
musculus), Cuvier's beaked whale (Ziphius cavirostris), four species of
Mesoplodont beaked whale (Mesoplodon spp.), dwarf and pygmy sperm whale
(Kogia sima and Kogia breviceps), and striped dolphin (Stenella
coeruleoalba), typically occur further offshore than the Project Area,
while short-finned pilot whales (Globicephala macrorhynchus) and
Atlantic spotted dolphins (Stenella frontalis) are typically found
further south than the Project Area (Hayes et al., 2019b). There are
stranding records of harp seals (Pagophilus groenlandicus) in
Massachusetts, but the species typically occurs north of the Project
Area and appearances in Massachusetts usually occur between January and
May, outside of the proposed survey dates (Hayes et al., 2019b). As
take of these species is not anticipated as a result of the proposed
activities, these species are not analyzed further.
The following subsections provide additional information on the
biology, habitat use, abundance, distribution, and the existing threats
to the non-ESA-listed and ESA-listed marine mammals that are both
common in the waters of the outer continental shelf (OCS) of Southern
New England and have the likelihood of occurring, at least seasonally,
in the Project Area and are, therefore, expected to potentially be
taken by the proposed activities.
North Atlantic Right Whale
The Western Atlantic stock of North Atlantic right whales ranges
primarily from calving grounds in coastal waters of the southeastern
United States to feeding grounds in New England waters and the Canadian
Bay of Fundy, Scotian Shelf, and Gulf of St. Lawrence (Hayes et al.,
2019). Surveys indicate that there are seven areas where NARWs
congregate seasonally: The coastal waters of the southeastern United
States, the Great South Channel, Jordan Basin, Georges Basin along the
northeastern edge of Georges Bank, Cape Cod and Massachusetts Bays, the
Bay of Fundy, and the Roseway Basin on the Scotian Shelf (Hayes et al.
2018). The closest of these seven areas is the Great South Channel,
which lies east of the Project Area, though none of these areas
directly overlaps the Project Area.
NMFS has designated two critical habitat areas for the NARW under
the ESA: the Gulf of Maine/Georges Bank region, and the southeast
calving grounds from North Carolina to Florida. NMFS's regulations at
50 CFR part 224.105 designated nearshore waters of the Mid-Atlantic
Bight as Mid-Atlantic U.S. Seasonal Management Areas (SMA) for right
whales in 2008. SMAs were developed to reduce the threat of collisions
between ships and right whales around their migratory route and calving
grounds. All vessels greater than 19.8 m (65 ft) in overall length must
operate at speeds of 10 knots (5.1 m/s) or less within these areas
during specific time periods. The Lease Area is located approximately
15 km southeast of the Block Island Sound SMA, which is active between
November 1 and April 30 each year. The Great South Channel SMA lies to
the northeast of the Lease Area and is active April 1 to July 31. NOAA
Fisheries may also establish Dynamic Management Areas (DMAs) when and
where NARWs are sighted outside SMAs. DMAs are generally in effect for
two weeks. During this time, vessels are encouraged to avoid these
areas or reduce speeds to 10 knots (5.1 m/s) or less while transiting
through these areas.
LaBrecque et al. 2015 identified ``biologically important areas
(BIAs)'' for cetaceans on the U.S. East Coast, including reproductive,
feeding, and migratory areas, as well as areas where small and resident
populations reside. The Project Area is encompassed by a right whale
BIA for migration from March to April and from November to December. A
feeding BIA for right whales from April to June was identified
northeast of the Project Area, east of Cape Cod.
The western North Atlantic population demonstrated overall growth
of 2.8 percent per year from 1990 to 2010, despite a decline in 1993
and no growth between 1997 and 2000 (Pace et al. 2017). However, since
2010 the population has been in decline, with a 99.99 percent
probability of a decline of just under 1 percent per year (Pace et al.
2017). Between 1990 and 2015, calving rates varied substantially, with
low calving rates coinciding with all three periods of decline or no
growth (Pace et al. 2017). In 2018, no new North Atlantic right whale
calves were documented in their calving grounds; this represented the
first time since annual NOAA aerial surveys began in 1989 that no new
right whale calves were observed. However, in 2019 at least seven right
whale calves were identified while ten calves have been recorded in
2020. Data indicates that the number of adult females fell from 200 in
2010 to 186 in 2015 while males fell from 283 to 272 in the same time
period (Pace et al., 2017). In addition, elevated North Atlantic right
whale mortalities have occurred since June 7, 2017. A total of 30
confirmed dead stranded whales (21 in Canada; 9 in the United States),
have been documented to date. This event has been declared an Unusual
Mortality Event (UME), with human interactions (i.e., fishery-related
entanglements and vessel strikes) identified as the most likely cause.
More information is available online at: https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2019-north-atlantic-right-whale-unusual-mortality-event.
Humpback Whale
Humpback whales are found worldwide in all oceans. Humpback whales
were listed as endangered under the Endangered Species Conservation Act
(ESCA) in June 1970. In 1973, the ESA replaced the ESCA, and humpbacks
continued to be listed as endangered. NMFS recently evaluated
[[Page 31861]]
the status of the species, and on September 8, 2016, NMFS divided the
species into 14 distinct population segments (DPS), removed the current
species-level listing, and in its place listed four DPSs as endangered
and one DPS as threatened (81 FR 62259; September 8, 2016). The
remaining nine DPSs were not listed. The West Indies DPS, which is not
listed under the ESA, is the only DPS of humpback whale that is
expected to occur in the Project Area. The best estimate of population
abundance for the West Indies DPS is 12,312 individuals, as described
in the NMFS Status Review of the Humpback Whale under the Endangered
Species Act (Bettridge et al., 2015).
Humpback whales in the Gulf of Maine stock typically feed in the
waters between the Gulf of Maine and Newfoundland during spring,
summer, and fall, but have been observed feeding in other areas, such
as off the coast of New York (Sieswerda et al. 2015). Humpback whales
are frequently piscivorous when in New England waters, feeding on
herring (Clupea harengus), sand lance (Ammodytes spp.), and other small
fishes, as well as euphausiids in the northern Gulf of Maine (Paquet et
al. 1997). During winter, the majority of humpback whales from North
Atlantic feeding areas (including the Gulf of Maine) mate and calve in
the West Indies, where spatial and genetic mixing among feeding groups
occurs, though significant numbers of animals are found in mid- and
high-latitude regions at this time and some individuals have been
sighted repeatedly within the same winter season, indicating that not
all humpback whales migrate south every winter (Waring et al., 2017).
Kraus et al. (2016) observed humpback whales in the RI/MA & MA WEAs
and surrounding areas during all seasons. Humpback whales were observed
most often during spring and summer months, with a peak from April to
June. Calves were observed 10 times and feeding was observed 10 times
during the Kraus et al. (2016) study. That study also observed one
instance of courtship behavior. Although humpback whales were rarely
seen during fall and winter surveys, acoustic data indicate that this
species may be present within the Massachusetts Wind Energy Area (WEA)
year-round, with the highest rates of acoustic detections in winter and
spring (Kraus et al. 2016).
A humpback whale BIA for feeding has been identified northeast of
the Lease Area in the Gulf of Maine, Stellwagen Bank, and the Great
South Channel from March through December (LaBrecque et al., 2015).
Since January 2016, elevated humpback whale mortalities have
occurred along the Atlantic coast from Maine through Florida. The event
has been declared a UME. Partial or full necropsy examinations have
been conducted on approximately half of the 111 known cases. A portion
of the whales have shown evidence of pre-mortem vessel strike; however,
this finding is not consistent across all of the whales examined so
more research is needed. NOAA is consulting with researchers that are
conducting studies on the humpback whale populations, and these efforts
may provide information on changes in whale distribution and habitat
use that could provide additional insight into how these vessel
interactions occurred. More detailed information is available at:
https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2019-humpback-whale-unusual-mortality-event-along-atlantic-coast (accessed
January 9, 2020). Three previous UMEs involving humpback whales have
occurred since 2000, in 2003, 2005, and 2006.
Fin Whale
The fin whale is the second largest baleen whale and is widely
distributed in all the world's oceans, but is most abundant in
temperate and cold waters (Aguilar and Garc[iacute]a-Vernet 2018). Fin
whales are presumed to migrate seasonally between feeding and breeding
grounds, but their migrations are less well defined than for other
baleen whales. In the North Atlantic, some feeding areas have been
identified but there are no known wintering areas (Aguilar and
Garc[iacute]a-Vernet 2018). Fin whales are found in the summer from
Baffin Bay, Spitsbergen, and the Barents Sea south to North Carolina
and the coast of Portugal (Rice 1998). Apparently not all individuals
migrate, because in winter they have been sighted from Newfoundland to
the Gulf of Mexico and the Caribbean Sea, and from the Faroes and
Norway south to the Canary Islands (Rice 1998). Fin whales off the
eastern United States, Nova Scotia, and the southeastern coast of
Newfoundland are believed to constitute a single stock under the
present International Whaling Commission (IWC) management scheme
(Donovan 1991), which has been called the Western North Atlantic stock.
Kraus et al. (2016) suggest that, compared to other baleen whale
species, fin whales have a high multi-seasonal relative abundance in
the Rhode Island/Massachusetts and Massachusetts Wind Energy Areas (RI/
MA & MA WEAs) and surrounding areas. Fin whales were observed in the MA
WEA) in spring and summer. This species was observed primarily in the
offshore (southern) regions of the RI/MA & MA WEAs during spring and
was found closer to shore (northern areas) during the summer months
(Kraus et al. 2016). Calves were observed three times and feeding was
observed nine times during the Kraus et al. (2016) study. Although fin
whales were largely absent from visual surveys in the RI/MA & MA WEAs
in the fall and winter months (Kraus et al. 2016), acoustic data
indicated that this species was present in the RI/MA & MA WEAs during
all months of the year.
The main threats to fin whales are fishery interactions and vessel
collisions (Waring et al., 2017). New England waters represent a major
feeding ground for fin whales. The Lease Area is flanked by two BIAs
for feeding fin whales--the area to the northeast is considered a BIA
year-round, while the area off the tip of Long Island to the southwest
is a BIA from March to October (LaBrecque et al. 2015).
Sei Whale
Sei whales occur worldwide, with a preference for oceanic waters
over shelf waters (Horwood 2018). The Nova Scotia stock of sei whales
can be found in deeper waters of the continental shelf edge waters of
the northeastern United States and northeastward to south of
Newfoundland. NOAA Fisheries considers sei whales occurring from the
U.S. East Coast to Cape Breton, Nova Scotia, and east to 42[deg] W as
the Nova Scotia stock of sei whales (Waring et al. 2016; Hayes et al.
2018). In the Northwest Atlantic, it is speculated that the whales
migrate from south of Cape Cod along the eastern Canadian coast in June
and July, and return on a southward migration again in September and
October (Waring et al. 2014; 2017).
Spring is the period of greatest abundance in U.S. waters, with
sightings concentrated along the eastern margin of Georges Bank and
into the Northeast Channel area, and along the southwestern edge of
Georges Bank in the area of Hydrographer Canyon (Waring et al., 2015).
Kraus et al. (2016) observed sei whales in the RI/MA and MA WEAs and
surrounding areas only between the months of March and June during the
2011-2015 NLPSC aerial survey. The number of sei whale observations was
less than half that of other baleen whale species in the two seasons in
which sei whales were observed (spring and summer). This species
demonstrated a distinct seasonal habitat use pattern that was
consistent
[[Page 31862]]
throughout the study. Calves were observed three times and feeding was
observed four times during the Kraus et al. (2016) study. Sei whales
were not observed in the MA WEA and nearby waters during the 2010-2017
Atlantic Marine Assessment Program for Protected Species (AMAPPS)
shipboard and aerial surveys. However, there were observations during
the 2016 and 2017 summer surveys that were identified as being either a
fin or sei whale. A BIA for feeding for sei whales occurs east of the
Lease Area from May through November (LaBrecque et al. 2015).
Minke Whale
Minke whales have a cosmopolitan distribution that spans ice-free
latitudes (Stewart and Leatherwood 1985). The Canadian East Coast stock
can be found in the area from the western half of the Davis Strait (45
[deg]W) to the Gulf of Mexico (Waring et al., 2017). This species
generally occupies waters less than 100 m deep on the continental
shelf. There appears to be a strong seasonal component to minke whale
distribution in which spring to fall are times of relatively widespread
and common occurrence, and when the whales are most abundant in New
England waters, while during winter the species appears to be largely
absent (Waring et al., 2017).
Kraus et al. (2016) observed minke whales in the RI/MA & MA WEAs
and surrounding areas primarily from May to June. This species
demonstrated a distinct seasonal habitat usage pattern that was
consistent throughout the study. Though minke whales were observed in
spring and summer months in the MA WEA, they were only observed in the
lease areas in the spring. Minke whales were not observed between
October and February, but acoustic data indicate the presence of this
species in the proposed Project Area in winter months. A BIA for
feeding for minke whales occurs east of the Lease Area from March
through November (LaBrecque et al., 2015).
Since January 2017, elevated minke whale strandings have occurred
along the Atlantic coast from Maine through South Carolina, with
highest numbers in Massachusetts, Maine, and New York. Partial or full
necropsy examinations have been conducted on more than 60 percent of
the 79 known cases. Preliminary findings in several of the whales have
shown evidence of human interactions or infectious disease. These
findings are not consistent across all of the whales examined, so more
research is needed. More information is available at: https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2019-minke-whale-unusual-mortality-event-along-atlantic-coast.
Sperm Whale
The distribution of the sperm whale in the U.S. Exclusive Economic
Zone (EEZ) occurs on the continental shelf edge, over the continental
slope, and into mid-ocean regions (Waring et al. 2015). The basic
social unit of the sperm whale appears to be the mixed school of adult
females plus their calves and some juveniles of both sexes, normally
numbering 20-40 animals in all. Sperm whales are somewhat migratory;
however, their migrations are not as specific as seen in most of the
baleen whale species. In the North Atlantic, there appears to be a
general shift northward during the summer, but there is no clear
migration in some temperate areas (Rice 1989). In summer, the
distribution of sperm whales includes the area east and north of
Georges Bank and into the Northeast Channel region, as well as the
continental shelf (inshore of the 100-m isobath) south of New England.
In the fall, sperm whale occurrence south of New England on the
continental shelf is at its highest level, and there remains a
continental shelf edge occurrence in the mid-Atlantic bight. In winter,
sperm whales are concentrated east and northeast of Cape Hatteras.
Their distribution is typically associated with waters over the
continental shelf break and the continental slope and into deeper
waters (Whitehead et al. 1991). Sperm whale concentrations near drop-
offs and areas with strong currents and steep topography are correlated
with high productivity. These whales occur almost exclusively found at
the shelf break, regardless of season.
Kraus et al. (2016) observed sperm whales four times in the RI/MA &
MA WEAs during the summer and fall from 2011 to 2015. Sperm whales,
traveling singly or in groups of three or four, were observed three
times in August and September of 2012, and once in June of 2015.
Long-Finned Pilot Whale
Long-finned pilot whales are found from North Carolina and north to
Iceland, Greenland and the Barents Sea (Waring et al., 2016). They are
generally found along the edge of the continental shelf (a depth of 330
to 3,300 feet (100 to 1,000 meters)), choosing areas of high relief or
submerged banks in cold or temperate shoreline waters. In the western
North Atlantic, long-finned pilot whales are pelagic, occurring in
especially high densities in winter and spring over the continental
slope, then moving inshore and onto the shelf in summer and autumn
following squid and mackerel populations (Reeves et al. 2002). They
frequently travel into the central and northern Georges Bank, Great
South Channel, and Gulf of Maine areas during the late spring and
remain through early fall (May and October) (Payne and Heinemann 1993).
Note that long-finned and short-finned pilot whales overlap
spatially along the mid-Atlantic shelf break between New Jersey and the
southern flank of Georges Bank (Payne and Heinemann 1993, Hayes et al.
2017) Long-finned pilot whales have occasionally been observed stranded
as far south as South Carolina, and short-finned pilot whale have
stranded as far north as Massachusetts (Hayes et al. 2017). The
latitudinal ranges of the two species therefore remain uncertain.
However, south of Cape Hatteras, most pilot whale sightings are
expected to be short-finned pilot whales, while north of approximately
42[deg] N, most pilot whale sightings are expected to be long-finned
pilot whales (Hayes et al. 2017). Based on the distributions described
in Hayes et al. (2017), pilot whale sightings in the Project Area would
most likely be long-finned pilot whales.
Kraus et al. (2016) observed pilot whales infrequently in the RI/MA
& MA WEAs and surrounding areas. Effort-weighted average sighting rates
for pilot whales could not be calculated. No pilot whales were observed
during the fall or winter, and these species were only observed 11
times in the spring and three times in the summer.
Atlantic White-Sided Dolphin
White-sided dolphins are found in cold temperate and sub-polar
waters of the North Atlantic, primarily in continental shelf waters to
the 100-m depth contour from central West Greenland to North Carolina
(Waring et al., 2017). The Gulf of Maine stock is most common in
continental shelf waters from Hudson Canyon to Georges Bank, and in the
Gulf of Maine and lower Bay of Fundy. Sighting data indicate seasonal
shifts in distribution (Northridge et al., 1997). During January to
May, low numbers of white-sided dolphins are found from Georges Bank to
Jeffreys Ledge (off New Hampshire), with even lower numbers south of
Georges Bank, as documented by a few strandings collected on beaches of
Virginia to South Carolina. From June through September, large numbers
of white-sided dolphins are found from Georges Bank to the lower Bay of
Fundy. From October to December, white-sided dolphins occur at
intermediate densities from southern Georges Bank to southern Gulf of
Maine
[[Page 31863]]
(Payne and Heinemann 1990). Sightings south of Georges Bank,
particularly around Hudson Canyon, occur year round but at low
densities.
Kraus et al. (2016) suggest that Atlantic white-sided dolphins
occur infrequently in the RI/MA & MA WEAs and surrounding areas.
Effort-weighted average sighting rates for Atlantic white-sided
dolphins could not be calculated, because this species was only
observed on eight occasions throughout the duration of the study
(October 2011 to June 2015). No Atlantic white-sided dolphins were
observed during the winter months, and this species was only sighted
twice in the fall and three times in the spring and summer.
Common Dolphin
The common dolphin is one of the most abundant and widely
distributed cetaceans, occurring in warm temperate and tropical regions
worldwide from about 60[deg] N to 50[deg] S (Perrin 2018). These
dolphins occur in groups of hundreds or thousands of individuals and
often associate with pilot whales or other dolphin species (Perrin
2018). Until recently, short-beaked and long-beaked common dolphins
were thought to be separate species but evidence now suggests that this
character distinction is based on ecology rather than genetics (Perrin
2018) and the Committee on Taxonomy now recognizes a single species
with three subspecies of common dolphin. The common dolphins occurring
in the Project Area are expected to be short-beaked common dolphins
(Delphinus delphis delphis; Perrin 2018) and would belong to the
Western North Atlantic stock (Hayes et al., 2018).
In the North Atlantic, short-beaked common dolphins are commonly
found over the continental shelf between the 100-m and 2,000-m isobaths
and over prominent underwater topography and east to the mid-Atlantic
Ridge (Waring et al., 2016). This species is found between Cape
Hatteras and Georges Bank from mid-January to May, although they
migrate onto the northeast edge of Georges Bank in the fall where large
aggregations occur (Kenney and Vigness-Raposa 2009), where large
aggregations occur on Georges Bank in fall (Waring et al. 2007).
Kraus et al. (2016) suggested that short-beaked common dolphins
occur year-round in the RI/MA & MA WEAs and surrounding areas. Short-
beaked common dolphins were the most frequently observed small cetacean
species within the Kraus et al. (2016) study area. Short-beaked common
dolphins were observed in the RI/MA & MA WEAs in all seasons but were
most frequently observed during the summer months, with peak sightings
in June and August. Short-beaked common dolphins were observed in the
MA WEA and nearby waters during all seasons of the 2010-2017 AMAPPS
surveys.
Bottlenose Dolphin
There are two distinct bottlenose dolphin ecotypes in the western
North Atlantic: the coastal and offshore forms (Waring et al., 2015).
The migratory coastal morphotype resides in waters typically less than
65.6 ft (20 m) deep, along the inner continental shelf (within 7.5 km
(4.6 miles) of shore), around islands, and is continuously distributed
south of Long Island, New York into the Gulf of Mexico. This migratory
coastal population is subdivided into 7 stocks based largely upon
spatial distribution (Waring et al. 2015). Generally, the offshore
migratory morphotype is found exclusively seaward of 34 km (21 miles)
and in waters deeper than 34 m (111.5 feet). This morphotype is most
expected in waters north of Long Island, New York (Waring et al. 2017;
Hayes et al. 2017; 2018). Bottlenose dolphins encountered in the
Project Area would likely belong to the Western North Atlantic Offshore
stock (Hayes et al. 2018). It is possible that a few animals could be
from the Northern Migratory Coastal stock, but they generally do not
range farther north than New Jersey.
Kraus et al. (2016) observed common bottlenose dolphins during all
seasons within the RI/MA & MA WEAs. Common bottlenose dolphins were the
second most commonly observed small cetacean species and exhibited
little seasonal variability in abundance. Common bottlenose dolphins
were observed in the MA WEA and nearby waters during spring, summer,
and fall of the 2010-2017 AMAPPS surveys.
Risso's Dolphins
Risso's dolphins are distributed worldwide in tropical and
temperate seas (Jefferson et al., 2008, 2014), and in the Northwest
Atlantic occur from Florida to eastern Newfoundland (Leatherwood et al.
1976; Baird and Stacey 1991). Off the northeastern U.S. coast, Risso's
dolphins are distributed along the continental shelf edge from Cape
Hatteras northward to Georges Bank during spring, summer, and autumn
(CETAP 1982; Payne et al., 1984). In winter, the range is in the mid-
Atlantic Bight and extends outward into oceanic waters (Payne et al.,
1984).
Risso's dolphins appear to prefer steep sections of the continental
shelf edge and deep offshore waters 100-1,000 m deep (Hartman 2018).
They are deep divers, feeding primarily on deep mesopelagic cephalopods
such as squid, octopus, and cuttlefish, and likely forage at night
(Hartman 2018).
Kraus et al. (2016) results suggest that Risso's dolphins occur
infrequently in the RI/MA & MA WEAs and surrounding areas. Risso's
dolphins were observed in the MA WEA and nearby waters during spring
and summer of the 2010-2017 AMAPPS surveys.
Harbor Porpoise
The harbor porpoise inhabits cool temperate to subarctic waters of
the Northern Hemisphere, generally within shallow coastal waters of the
continental shelf but occasionally travel over deeper, offshore waters
(Jefferson et al., 2008). They are usually seen in small groups of one
to three but occasionally form much larger groups (Bj[oslash]rge and
Tolley 2018).
There are likely four populations in the western North Atlantic:
Gulf of Maine/Bay of Fundy, Gulf of St. Lawrence, Newfoundland, and
Greenland (Gaskin 1984, 1992; Hayes et al., 2019). In the Project Area,
only the Gulf of Maine/Bay of Fundy stock may be present. This stock is
found in U.S. and Canadian Atlantic waters and is concentrated in the
northern Gulf of Maine and southern Bay of Fundy region, generally in
waters less than 150 m deep (Waring et al., 2017). During fall
(October-December) and spring (April-June) harbor porpoises are widely
dispersed from New Jersey to Maine. During winter (January to March),
intermediate densities of harbor porpoises can be found in waters off
New Jersey to North Carolina, and lower densities are found in waters
off New York to New Brunswick, Canada. They are seen from the coastline
to deep waters (>1800 m; Westgate et al. 1998), although the majority
of the population is found over the continental shelf (Waring et al.,
2017).
Kraus et al. (2016) indicate that harbor porpoises occur within the
RI/MA & MA WEAs in fall, winter, and spring. Harbor porpoises were
observed in groups ranging in size from three to 15 individuals and
were primarily observed in the Kraus et al. (2016) study area from
November through May, with very few sightings during June through
September. Harbor porpoises were observed in the MA WEA and nearby
waters during spring and fall of the 2010-2017 AMAPPS surveys.
Harbor Seal
The harbor seal has a wide distribution throughout coastal waters
between 30[deg] N and ~80[deg] N (Teilmann and Galatius 2018). Harbor
seals are
[[Page 31864]]
year-round inhabitants of the coastal waters of eastern Canada and
Maine (Katona et al. 1993), and occur seasonally along the coasts from
southern New England to New Jersey from September through late May
(Barlas 1999; Katona et al., 1993; Schneider and Payne 1983; Schroeder
2000). A northward movement from southern New England to Maine and
eastern Canada occurs prior to the pupping season, which takes place
from mid-May through June (Kenney 1994; Richardson 1976; Whitman and
Payne 1990; Wilson 1978). Harbor seals are generally present in the
Project Area seasonally, from September through May (Hayes et al.,
2019).
Kraus et al. (2016) observed harbor seals in the RI/MA and MA WEAs
and surrounding areas during the 2011-2015 NLPSC aerial survey, but
this survey was designed to target large cetaceans so locations and
numbers of seal observations were not included in the study report.
Harbor seals have five major haulout sites in and near the RI/MA and MA
WEAs: Monomoy Island, the northwestern side of Nantucket Island, Nomans
Land, the north side of Gosnold Island, and the southeastern side of
Naushon Island (Payne and Selzer 1989). Harbor seals were observed in
the MA WEA and nearby waters during spring, summer, and fall of the
2010-2017 AMAPPS surveys.
Gray Seal
Gray seals are found throughout the temperate and subarctic waters
of the North Atlantic (King 1983). In the northwestern Atlantic, they
occur from Labrador sound to Massachusetts (King 1983). Gray seals
often haul out on remote, exposed islands, shoals, and unstable
sandbars (Jefferson et al., 2008). Though they spend most of their time
in coastal waters, gray seals can dive to depths of 300 m (984 ft) and
frequently forage on the outer continental shelf (Jefferson et al.,
2008).
Gray seals in the Project Area belong to the western North Atlantic
stock. The range for this stock is thought to be from New Jersey to
Labrador. Current population trends show that gray seal abundance is
likely increasing in the U.S. Atlantic EEZ (Waring et al., 2017).
Although the rate of increase is unknown, surveys conducted since their
arrival in the 1980s indicate a steady increase in abundance in both
Maine and Massachusetts (Waring et al., 2017). It is believed that
recolonization by Canadian gray seals is the source of the U.S.
population (Waring et al., 2017). In U.S. waters, gray seals currently
pup at four established colonies from late December to mid-February:
Muskeget and Monomoy Islands in Massachusetts, and Green and Seal
Islands in Maine (Hayes et al., 2019). Pupping was also observed in the
early 1980s on small islands in Nantucket-Vineyard Sound and since
2010, pupping has been documented at Nomans Island in Massachusetts
(Hayes et al., 2019). The distributions of individuals from different
breeding colonies overlap outside of the breeding season. Gray seals
may be present in the Project Area year-round (Hayes et al., 2018).
Since July 2018, elevated numbers of harbor seal and gray seal
mortalities have occurred across Maine, New Hampshire and
Massachusetts. This event has been declared a UME. Additionally, seals
showing clinical signs of stranding have occurred as far south as
Virginia, although not in elevated numbers. Therefore the UME
investigation now encompasses all seal strandings from Maine to
Virginia. Between July 1, 2018 and March 13, 2020, a total of 3,152
seal strandings have been recorded as part of this designated Northeast
Pinniped UME. Based on tests conducted so far, the main pathogen found
in the seals is phocine distemper virus. Additional testing to identify
other factors that may be involved in this UME are underway. More
information is available at: https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along.
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 (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65
decibel (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. Marine mammal hearing
groups and their associated hearing ranges are provided in Table 4.
Table 4--Marine Mammal Hearing Groups (NMFS, 2018)
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
cephalorhynchid, Lagenorhynchus
cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) 50 Hz to 86 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 39 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al. 2007) and PW pinniped (approximation).
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,
[[Page 31865]]
especially in the higher frequency range (Hemil[auml] et al., 2006;
Kastelein et al., 2009; Reichmuth and Holt, 2013).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Fourteen marine mammal species (12 cetacean and two pinniped (both
phocid) species) have the reasonable potential to co-occur with the
proposed survey activities. Of the cetacean species that may be
present, six are classified as low-frequency cetaceans (i.e., all
mysticete species), five are classified as mid-frequency cetaceans
(i.e., all delphinid and ziphiid species and the sperm whale), and one
is classified as high-frequency cetaceans (i.e., harbor porpoise).
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a summary and discussion of the ways that
components of the specified activity may impact marine mammals and
their habitat. The Estimated Take by Incidental Harassment section
later in this document includes a quantitative analysis of the number
of individuals that are expected to be taken by this activity. The
Negligible Impact Analysis and Determination section considers the
content of this section, the Estimated Take by Incidental Harassment
section, and the Proposed Mitigation section, to draw conclusions
regarding the likely impacts of these activities on the reproductive
success or survivorship of individuals and how those impacts on
individuals are likely to impact marine mammal species or stocks.
Description of Sound Sources
This section contains a brief technical background on sound, on the
characteristics of certain sound types, and on metrics used in this
proposal inasmuch as the information is relevant to the specified
activity and to a discussion of the potential effects of the specified
activity on marine mammals found later in this document. For general
information on sound and its interaction with the marine environment,
please see, e.g., Au and Hastings (2008); Richardson et al. (1995).
Sound travels in waves, the basic components of which are
frequency, wavelength, velocity, and amplitude. Frequency is the number
of pressure waves that pass by a reference point per unit of time and
is measured in hertz (Hz) or cycles per second. Wavelength is the
distance between two peaks or corresponding points of a sound wave
(length of one cycle). Higher frequency sounds have shorter wavelengths
than lower frequency sounds, and typically attenuate (decrease) more
rapidly, except in certain cases in shallower water. Amplitude is the
height of the sound pressure wave or the ``loudness'' of a sound and is
typically described using the relative unit of the decibel (dB). A
sound pressure level (SPL) in dB is described as the ratio between a
measured pressure and a reference pressure (for underwater sound, this
is 1 microPascal ([mu]Pa)), and is a logarithmic unit that accounts for
large variations in amplitude; therefore, a relatively small change in
dB corresponds to large changes in sound pressure. The source level
(SL) represents the SPL referenced at a distance of 1 m from the source
(referenced to 1 [mu]Pa), while the received level is the SPL at the
listener's position (referenced to 1 [mu]Pa).
Root mean square (rms) is the quadratic mean sound pressure over
the duration of an impulse. Root mean square is calculated by squaring
all of the sound amplitudes, averaging the squares, and then taking the
square root of the average. Root mean square accounts for both positive
and negative values; squaring the pressures makes all values positive
so that they may be accounted for in the summation of pressure levels
(Hastings and Popper, 2005). This measurement is often used in the
context of discussing behavioral effects, in part because behavioral
effects, which often result from auditory cues, may be better expressed
through averaged units than by peak pressures.
Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s)
represents the total energy in a stated frequency band over a stated
time interval or event, and considers both intensity and duration of
exposure. The per-pulse SEL is calculated over the time window
containing the entire pulse (i.e., 100 percent of the acoustic energy).
SEL is a cumulative metric; it can be accumulated over a single pulse,
or calculated over periods containing multiple pulses. Cumulative SEL
represents the total energy accumulated by a receiver over a defined
time window or during an event. Peak sound pressure (also referred to
as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous
sound pressure measurable in the water at a specified distance from the
source, and is represented in the same units as the rms sound pressure.
When underwater objects vibrate or activity occurs, sound-pressure
waves are created. These waves alternately compress and decompress the
water as the sound wave travels. Underwater sound waves radiate in a
manner similar to ripples on the surface of a pond and may be either
directed in a beam or beams or may radiate in all directions
(omnidirectional sources). The compressions and decompressions
associated with sound waves are detected as changes in pressure by
aquatic life and man-made sound receptors such as hydrophones.
Even in the absence of sound from the specified activity, the
underwater environment is typically loud due to ambient sound, which is
defined as environmental background sound levels lacking a single
source or point (Richardson et al., 1995). The sound level of a region
is defined by the total acoustical energy being generated by known and
unknown sources. These sources may include physical (e.g., wind and
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds
produced by marine mammals, fish, and invertebrates), and anthropogenic
(e.g., vessels, dredging, construction) sound. A number of sources
contribute to ambient sound, including wind and waves, which are a main
source of naturally occurring ambient sound for frequencies between 200
hertz (Hz) and 50 kilohertz (kHz) (Mitson, 1995). In general, ambient
sound levels tend to increase with increasing wind speed and wave
height. Precipitation can become an important component of total sound
at frequencies above 500 Hz, and possibly down to 100 Hz during quiet
times. Marine mammals can contribute significantly to ambient sound
levels, as can some fish and snapping shrimp. The frequency band for
biological contributions is from approximately 12 Hz to over 100 kHz.
Sources of ambient sound related to human activity include
transportation (surface vessels), dredging and construction, oil and
gas drilling and production, geophysical surveys, sonar, and
explosions. Vessel noise typically dominates the total ambient sound
for frequencies between 20 and 300 Hz. In general, the frequencies of
anthropogenic sounds are below 1 kHz and, if higher frequency sound
levels are created, they attenuate rapidly.
The sum of the various natural and anthropogenic sound sources that
comprise ambient sound at any given location and time depends not only
on the source levels (as determined by current weather conditions and
levels of biological and human activity) but also on the ability of
sound to propagate through the environment. In turn, sound propagation
is dependent on the spatially and temporally varying properties of the
water column and sea floor, and is frequency-dependent. As a
[[Page 31866]]
result of the dependence on a large number of varying factors, ambient
sound levels can be expected to vary widely over both coarse and fine
spatial and temporal scales. Sound levels at a given frequency and
location can vary by 10-20 dB from day to day (Richardson et al.,
1995). The result is that, depending on the source type and its
intensity, sound from the specified activity may be a negligible
addition to the local environment or could form a distinctive signal
that may affect marine mammals.
Sounds are often considered to fall into one of two general types:
Pulsed and non-pulsed. The distinction between these two sound types is
important because they have differing potential to cause physical
effects, particularly with regard to hearing (e.g., Ward, 1997 in
Southall et al., 2007). Please see Southall et al. (2007) for an in-
depth discussion of these concepts. The distinction between these two
sound types is not always obvious, as certain signals share properties
of both pulsed and non-pulsed sounds. A signal near a source could be
categorized as a pulse, but due to propagation effects as it moves
farther from the source, the signal duration becomes longer (e.g.,
Greene and Richardson, 1988).
Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic
booms, impact pile driving) produce signals that are brief (typically
considered to be less than one second), broadband, atonal transients
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur
either as isolated events or repeated in some succession. Pulsed sounds
are all characterized by a relatively rapid rise from ambient pressure
to a maximal pressure value followed by a rapid decay period that may
include a period of diminishing, oscillating maximal and minimal
pressures, and generally have an increased capacity to induce physical
injury as compared with sounds that lack these features.
Non-pulsed sounds can be tonal, narrowband, or broadband, brief or
prolonged, and may be either continuous or intermittent (ANSI, 1995;
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals
of short duration but without the essential properties of pulses (e.g.,
rapid rise time). Examples of non-pulsed sounds include those produced
by vessels, aircraft, machinery operations such as drilling or
dredging, vibratory pile driving, and active sonar systems. The
duration of such sounds, as received at a distance, can be greatly
extended in a highly reverberant environment.
Potential Effects of Underwater Sound
For study-specific citations, please see that work. 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
potentially 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). 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.
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 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 or other 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 describe the more severe effects (i.e., certain non-auditory
physical or physiological effects) only briefly as we do not expect
that there is a reasonable likelihood that HRG surveys may result in
such effects (see below for further discussion). 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). The activities considered here do not
involve the use of devices such as explosives or mid-frequency tactical
sonar that are associated with these types of effects.
Threshold Shift--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). Marine
mammals exposed to high-intensity sound, or to lower-intensity sound
for prolonged periods, can experience hearing threshold shift (TS),
which is the loss of hearing sensitivity at certain frequency ranges
(Finneran, 2015). TS 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). Repeated sound exposure that leads to TTS
could cause PTS. 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). 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.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans, but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several decibels above (a 40-dB threshold shift approximates PTS onset;
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB
threshold shift approximates TTS onset; e.g., Southall
[[Page 31867]]
et al. 2007). Based on data from terrestrial mammals, a precautionary
assumption is that the PTS thresholds for impulse sounds (such as
impact pile driving pulses as received close to the source) are at
least 6 dB higher than the TTS threshold on a peak-pressure basis and
PTS cumulative sound exposure level thresholds are 15 to 20 dB higher
than TTS cumulative sound exposure level thresholds (Southall et al.,
2007). Given the higher level of sound or longer exposure duration
necessary to cause PTS as compared with TTS, it is considerably less
likely that PTS could occur.
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. Few data
on sound levels and durations necessary to elicit mild TTS have been
obtained for marine mammals.
Marine mammal hearing plays a critical role in communication with
conspecifics, and interpretation of 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. 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 occurs 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 time when
communication is critical for successful mother/calf interactions could
have more serious impacts.
Currently, TTS data only exist for four species of cetaceans
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis))
and three species of pinnipeds (northern elephant seal (Mirounga
angustirostris), harbor seal, and California sea lion (Zalophus
californianus)) exposed to a limited number of sound sources (i.e.,
mostly tones and octave-band noise) in laboratory settings (Finneran,
2015). TTS was not observed in trained spotted (Phoca largha) and
ringed (Pusa hispida) seals exposed to impulsive noise at levels
matching previous predictions of TTS onset (Reichmuth et al., 2016). In
general, harbor seals and harbor porpoises have a lower TTS onset than
other measured pinniped or cetacean species (Finneran, 2015).
Additionally, the existing marine mammal TTS data come from a limited
number of individuals within these species. There are no data available
on noise-induced hearing loss for mysticetes. For summaries of data on
TTS in marine mammals or for further discussion of TTS onset
thresholds, please see Southall et al. (2007), Finneran and Jenkins
(2012), Finneran (2015), and NMFS (2018).
Animals in the Project Area during the proposed survey are unlikely
to incur TTS due to the characteristics of the sound sources, which
include relatively low source levels and generally very short pulses
and duration of the sound. Even for high-frequency cetacean species
(e.g., harbor porpoises), which may have increased sensitivity to TTS
(Lucke et al., 2009; Kastelein et al., 2012b), individuals would have
to make a very close approach and also remain very close to vessels
operating these sources in order to receive multiple exposures at
relatively high levels, as would be necessary to cause TTS.
Intermittent exposures--as would occur due to the brief, transient
signals produced by these sources--require a higher cumulative SEL to
induce TTS than would continuous exposures of the same duration (i.e.,
intermittent exposure results in lower levels of TTS) (Mooney et al.,
2009a; Finneran et al., 2010). Moreover, most marine mammals would more
likely avoid a loud sound source rather than swim in such close
proximity as to result in TTS. Kremser et al. (2005) noted that the
probability of a cetacean swimming through the area of exposure when a
sub-bottom profiler emits a pulse is small--because if the animal was
in the area, it would have to pass the transducer at close range in
order to be subjected to sound levels that could cause TTS and would
likely exhibit avoidance behavior to the area near the transducer
rather than swim through at such a close range. Further, the restricted
beam shape of the majority of the geophysical survey equipment proposed
for use makes it unlikely that an animal would be exposed more than
briefly during the passage of the vessel.
Behavioral Effects--Behavioral disturbance may include a variety of
effects, including subtle changes in behavior (e.g., minor or brief
avoidance of an area or changes in vocalizations), more conspicuous
changes in similar behavioral activities, and more sustained and/or
potentially severe reactions, such as displacement from or abandonment
of high-quality habitat. Behavioral responses to sound are highly
variable and context-specific and any reactions depend on numerous
intrinsic and extrinsic factors (e.g., species, state of maturity,
experience, current activity, reproductive state, auditory sensitivity,
time of day), as well as the interplay between factors (e.g.,
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007;
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not
only among individuals but also within an individual, depending on
previous experience with a sound source, context, and numerous other
factors (Ellison et al., 2012), and can vary depending on
characteristics associated with the sound source (e.g., whether it is
moving or stationary, number of sources, distance from the source).
Please see Appendices B-C of Southall et al. (2007) for a review of
studies involving marine mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2003). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure. As noted, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with
captive marine mammals have showed pronounced behavioral reactions,
including avoidance of loud sound sources (Ridgway et al., 1997;
Finneran et al., 2003). Observed responses of wild marine mammals to
loud pulsed sound sources (typically airguns or acoustic harassment
devices) have been varied but often consist of avoidance behavior or
other behavioral changes suggesting discomfort (Morton and Symonds,
2002; see also Richardson et al., 1995;
[[Page 31868]]
Nowacek et al., 2007). However, many delphinids approach low-frequency
airgun source vessels with no apparent discomfort or obvious behavioral
change (e.g., Barkaszi et al., 2012), indicating the importance of
frequency output in relation to the species' hearing sensitivity.
Available studies show wide variation in response to underwater
sound; therefore, it is difficult to predict specifically how any given
sound in a particular instance might affect marine mammals perceiving
the signal. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely and 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; Costa et al., 2003; 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. The impact
of an alteration to dive behavior 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.
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., 2006; 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.
Variations in respiration naturally vary with different behaviors
and alterations to breathing 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. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, 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 (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007; Gailey et al., 2016).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior 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 increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003; Foote et al., 2004), while 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). In some cases, animals may cease sound
production during production of aversive signals (Bowles et al., 1994).
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, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from airgun surveys (Malme et al.,
1984). Avoidance may be short-term, with animals returning to the area
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996;
Stone et al., 2000; Morton and Symonds, 2002; 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).
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, marine mammal strandings
(Evans and England, 2001). However, it should be noted that response to
a perceived predator does not necessarily invoke flight (Ford and
Reeves, 2008), and whether individuals are solitary or in groups may
influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors 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 (e.g., Beauchamp and
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In
addition, 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). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a five-day period did not cause any
sleep deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent
[[Page 31869]]
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). Note that there is a
difference between multi-day substantive behavioral reactions and
multi-day anthropogenic activities. For example, just because an
activity lasts for multiple days does not necessarily mean that
individual animals are either exposed to activity-related stressors for
multiple days or, further, exposed in a manner resulting in sustained
multi-day substantive behavioral responses.
We expect that some marine mammals may exhibit behavioral responses
to the HRG survey activities in the form of avoidance of the area
during the activity, especially the naturally shy harbor porpoise,
while others such as delphinids might be attracted to the survey
activities out of curiosity. However, because the HRG survey equipment
operates from a moving vessel, and the maximum radius to the Level B
harassment threshold is relatively small, the area and time that this
equipment would be affecting a given location is very small. Further,
once an area has been surveyed, it is not likely that it will be
surveyed again, thereby reducing the likelihood of repeated impacts
within the Project Area.
We have also considered the potential for severe behavioral
responses such as stranding and associated indirect injury or mortality
from Mayflower's use of HRG survey equipment. Commenters on previous
IHAs involving HRG surveys have referenced a 2008 mass stranding of
approximately 100 melon-headed whales in a Madagascar lagoon system. An
investigation of the event indicated that use of a high-frequency
mapping system (12-kHz multibeam echosounder) was the most plausible
and likely initial behavioral trigger of the event, while providing the
caveat that there is no unequivocal and easily identifiable single
cause (Southall et al., 2013). The investigatory panel's conclusion was
based on (1) very close temporal and spatial association and directed
movement of the survey with the stranding event; (2) the unusual nature
of such an event coupled with previously documented apparent behavioral
sensitivity of the species to other sound types (Southall et al., 2006;
Brownell et al., 2009); and (3) the fact that all other possible
factors considered were determined to be unlikely causes. Specifically,
regarding survey patterns prior to the event and in relation to
bathymetry, the vessel transited in a north-south direction on the
shelf break parallel to the shore, ensonifying large areas of deep-
water habitat prior to operating intermittently in a concentrated area
offshore from the stranding site; this may have trapped the animals
between the sound source and the shore, thus driving them towards the
lagoon system. The investigatory panel systematically excluded or
deemed highly unlikely nearly all potential reasons for these animals
leaving their typical pelagic habitat for an area extremely atypical
for the species (i.e., a shallow lagoon system). Notably, this was the
first time that such a system has been associated with a stranding
event. The panel also noted several site- and situation-specific
secondary factors that may have contributed to the avoidance responses
that led to the eventual entrapment and mortality of the whales.
Specifically, shoreward-directed surface currents and elevated
chlorophyll levels in the area preceding the event may have played a
role (Southall et al., 2013). The report also notes that prior use of a
similar system in the general area may have sensitized the animals and
also concluded that, for odontocete cetaceans that hear well in higher
frequency ranges where ambient noise is typically quite low, high-power
active sonars operating in this range may be more easily audible and
have potential effects over larger areas than low frequency systems
that have more typically been considered in terms of anthropogenic
noise impacts. It is, however, important to note that the relatively
lower output frequency, higher output power, and complex nature of the
system implicated in this event, in context of the other factors noted
here, likely produced a fairly unusual set of circumstances that
indicate that such events would likely remain rare and are not
necessarily relevant to use of lower-power, higher-frequency systems
more commonly used for HRG survey applications. The risk of similar
events recurring is likely very low, given the extensive use of active
acoustic systems used for scientific and navigational purposes
worldwide on a daily basis and the lack of direct evidence of such
responses previously reported.
Stress Responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an animal's first and sometimes most
economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine 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, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the 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 functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also 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
[[Page 31870]]
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).
NMFS does not expect that the generally short-term, intermittent,
and transitory HRG activities would create conditions of long-term,
continuous noise and chronic acoustic exposure leading to long-term
physiological stress responses in marine 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, navigation) (Richardson et al., 1995; 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. 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.
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
if disrupting behavioral patterns. It is important to distinguish TTS
and PTS, which persist after the sound exposure, from masking, which
occurs during the sound exposure. Because masking (without resulting in
TS) is not associated with abnormal physiological function, it is not
considered a physiological effect, but rather a potential behavioral
effect.
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) 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).
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 of the increase from distant commercial shipping
(Hildebrand, 2009). All anthropogenic sound sources, but especially
chronic and lower-frequency signals (e.g., from vessel traffic),
contribute to elevated ambient sound levels, thus intensifying masking.
Marine mammal communications would not likely be masked appreciably
by the HRG equipment given the directionality of the signals (for most
geophysical survey equipment types proposed for use (Table 1) and the
brief period when an individual mammal is likely to be within its beam.
Vessel Strike
Vessel strikes of marine mammals can cause significant wounds,
which may lead to the death of the animal. An animal at the surface
could be struck directly by a vessel, a surfacing animal could hit the
bottom of a vessel, or a vessel's propeller could injure an animal just
below the surface. 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).
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, such as the North Atlantic right whale, 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. Smaller marine mammals (e.g., bottlenose
dolphin) move quickly through the water column and are often seen
riding the bow wave of large ships. 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 results in death (Knowlton and Kraus 2001;
Laist et al., 2001; Jensen and Silber 2003; Vanderlaan and Taggart
2007). In assessing records with known vessel speeds, 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 24.1 km/h (14.9 mph; 13 kn). Given the slow vessel speeds
and predictable course necessary for data acquisition, ship strike is
unlikely to occur during the geophysical surveys. Marine mammals would
be able to easily avoid the survey vessel due to the slow vessel speed.
Further, Mayflower would implement measures (e.g., protected species
monitoring, vessel speed restrictions and separation distances; see
Proposed Mitigation) set forth in the BOEM lease to reduce the risk of
a vessel strike to marine mammal species in the Project Area.
Anticipated Effects on Marine Mammal Habitat
The proposed activities would not result in permanent impacts to
habitats used directly by marine mammals, but may have potential minor
and short-term impacts to food sources such as forage fish. The
proposed activities could affect acoustic habitat (see masking
discussion above), but meaningful impacts are unlikely. There are no
feeding areas, rookeries, or mating grounds known to be biologically
important to marine mammals within the proposed Project Area with the
exception of feeding BIAs for right, humpback, fin, and sei whales and
a migratory BIA for right whales which were described previously. The
HRG survey equipment will not contact the substrate and does not
represent a
[[Page 31871]]
source of pollution. Impacts to substrate or from pollution are
therefore not discussed further.
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).
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). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. Short duration, sharp
sounds can cause overt or subtle changes in fish behavior and local
distribution. The reaction of fish to noise depends on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Several studies
have demonstrated that impulse 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). However, some studies have shown no or slight
reaction to impulse sounds (e.g., Pena et al., 2013; Wardle et al.,
2001; Jorgenson and Gyselman, 2009; Cott et al., 2012). More commonly,
though, the impacts of noise on fish are temporary.
We are not aware of any available literature on impacts to marine
mammal prey from sound produced by HRG survey equipment. However, as
the HRG survey equipment introduces noise to the marine environment,
there is the potential for it to result in avoidance of the area around
the HRG survey activities on the part of marine mammal prey. The
duration of fish avoidance of an area after HRG surveys depart the area
is unknown, but a rapid return to normal recruitment, distribution and
behavior is anticipated. In general, impacts to marine mammal prey
species are expected to be minor and temporary due to the expected
short daily duration of the proposed HRG survey, the fact that the
proposed survey is mobile rather than stationary, and the relatively
small areas potentially affected. The areas likely impacted by the
proposed activities are relatively small compared to the available
habitat in the Atlantic Ocean. Any behavioral avoidance by fish of the
disturbed area would still leave significantly large areas of fish and
marine mammal foraging habitat in the nearby vicinity. Based on the
information discussed herein, we conclude that impacts of the specified
activity are not likely to have more than short-term adverse effects on
any prey habitat or populations of prey species. Because of the
temporary nature of the disturbance, and the availability of similar
habitat and resources (e.g., prey species) in the surrounding area, any
impacts to marine mammal habitat are not expected to result in
significant or long-term consequences for individual marine mammals, or
to contribute to adverse impacts on their populations. Effects to
habitat will not be discussed further in this document.
Estimated Take
This section provides an estimate of the number of incidental takes
proposed for authorization through this IHA, which will inform both
NMFS' consideration of ``small numbers'' and the negligible impact
determination.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes would be by Level B harassment only in the form of
disruption of behavioral patterns for individual marine mammals
resulting from exposure to HRG sources. Based on the nature of the
activity and the anticipated effectiveness of the mitigation measures
(i.e., exclusion zones and shutdown measures), discussed in detail
below in Proposed Mitigation section, Level A harassment is neither
anticipated nor proposed to be authorized.
As described previously, no mortality is anticipated or proposed to
be authorized for this activity. Below we describe how the take is
estimated.
Generally speaking, we estimate take by considering: (1) Acoustic
thresholds above which NMFS believes the best available science
indicates marine mammals will be behaviorally harassed or incur some
degree of permanent hearing impairment; (2) the area or volume of water
that will be ensonified above these levels in a day; (3) the density or
occurrence of marine mammals within these ensonified areas; and, (4)
and the number of days of activities. We note that while these basic
factors can contribute to a basic calculation to provide an initial
prediction of takes, additional information that can qualitatively
inform take estimates is also sometimes available (e.g., previous
monitoring results or average group size). Below, we describe the
factors considered here in more detail and present the proposed take
estimate.
Acoustic Thresholds
Using the best available science, NMFS has developed acoustic
thresholds that identify the received level of underwater sound above
which exposed marine mammals would be reasonably expected to be
behaviorally harassed (equated to Level B harassment) or to incur PTS
of some degree (equated to Level A harassment).
Level B Harassment for non-explosive sources--Though significantly
driven by received level, the onset of 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 (Southall et al., 2007,
Ellison et al., 2012). Based on what the available science indicates
and the practical need to use a threshold based on a factor that is
both predictable and measurable for most activities, NMFS uses a
generalized acoustic threshold based on received level to estimate the
onset of behavioral harassment. NMFS predicts that marine mammals are
likely to be behaviorally
[[Page 31872]]
harassed in a manner we consider Level B harassment when exposed to
underwater anthropogenic noise above received levels of 160 dB re 1
[mu]Pa (rms) for impulsive and/or intermittent sources (e.g., impact
pile driving) and 120 dB rms for continuous sources (e.g., vibratory
driving). Mayflower's proposed activity includes the use of impulsive
sources (geophysical survey equipment), and therefore use of the 160 dB
re 1 [mu]Pa (rms) threshold is applicable.
Level A harassment for non-explosive sources--NMFS' Technical
Guidance for Assessing the Effects of Anthropogenic Sound on Marine
Mammal Hearing (Version 2.0) (Technical Guidance, 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 components of Mayflower's proposed
activity includes the use of impulsive sources.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal functional hearing groups were calculated. The
updated acoustic thresholds for impulsive sounds (such as HRG survey
equipment) contained in the Technical Guidance (NMFS, 2018) were
presented as dual metric acoustic thresholds using both
SELcum and peak sound pressure level metrics. As dual
metrics, NMFS considers onset of PTS (Level A harassment) to have
occurred when either one of the two metrics is exceeded (i.e., metric
resulting in the largest isopleth). The SELcum metric
considers both level and duration of exposure, as well as auditory
weighting functions by marine mammal hearing group.
These thresholds are provided in Table 5 below. The references,
analysis, and methodology used in the development of the thresholds are
described in NMFS 2018 Technical Guidance, which may be accessed at:
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS onset acoustic thresholds * (Received Level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: L pk,flat: 219 dB; Cell 2: LE,LF,24h: 199 dB.
L E,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,MF,24h: 198 dB.
LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,HF,24h: 173 dB.
LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 218 dB Cell 8: LE,PW,24h: 201 dB.
LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 232 dB; Cell 10: LE,OW,24h: 219 dB.
LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
NMFS considers the data provided by Crocker and Fratantonio (2016)
to represent the best available information on source levels associated
with HRG equipment and therefore recommends that source levels provided
by Crocker and Fratantonio (2016) be incorporated in the method
described above to estimate isopleth distances to the Level B
harassment threshold. In cases when the source level for a specific
type of HRG equipment is not provided in Crocker and Fratantonio
(2016), NMFS recommends that either the source levels provided by the
manufacturer be used, or, in instances where source levels provided by
the manufacturer are unavailable or unreliable, a proxy from Crocker
and Fratantonio (2016) be used instead. Table 2 shows the HRG equipment
types that may be used during the proposed surveys and the sound levels
associated with those HRG equipment types. Tables 2 and 4 of Appendix B
in the IHA application shows the literature sources for the sound
source levels that are shown in Table 2 and that were incorporated into
the modeling of Level B isopleth distances to the Level B harassment
threshold.
Results of modeling using the methodology described above indicated
that, of the HRG survey equipment planned for use by Mayflower that has
the potential to result in harassment of marine mammals, sound produced
by the Geomarine Geo-Spark 400 tip sparker would propagate furthest to
the Level B harassment threshold (Table 6); therefore, for the purposes
of the exposure analysis, it was assumed the Geomarine Geo-Spark 400
tip sparker would be active during the entire duration of the surveys.
Thus the distance to the isopleth corresponding to the threshold for
Level B harassment for the Geomarine Geo-Spark 400 tip sparker
(estimated at 141 m; Table 6) was used as the basis of the take
calculation for all marine mammals. Note that this results in a
conservative estimate of the total ensonified area resulting from the
proposed activities as Mayflower may not operate the Geomarine Geo-
Spark 400 tip sparker during the entire proposed survey, and for any
survey segments in which it is not ultimately operated, the distance to
the Level B harassment threshold would be less than 141 m (Table 6).
However, as Mayflower cannot predict the precise number of survey days
that will require the use of the Geomarine Geo-Spark 400 tip sparker,
it was assumed that it would be operated during the entire duration of
the proposed surveys.
Table 6--Modeled Radial Distances From HRG Survey Equipment to Isopleths Corresponding to Level A and Level B Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
Radial distance to level A harassment threshold (m) * Radial distance
-------------------------------------------------------------------- to level B
harassment
Sound source threshold (m)
Low frequency Mid frequency High frequency Phocid pinnipeds -----------------
cetaceans cetaceans cetaceans (underwater) All marine
mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
Innomar SES-2000 Medium-100 Parametric............................ <1 <1 60 <1 116
[[Page 31873]]
Edgetech 2000-DSS................................................. <1 <1 3 <1 5
Geomarine Geo-Spark 400 tip sparker (800 Joules).................. <1 <1 8 <1 141
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Distances to the Level A harassment threshold based on the larger of the dual criteria (peak SPL and SELcum) are shown. For all sources the SELcum
metric resulted in larger isopleth distances.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal functional hearing groups (Table 5), were also
calculated. The updated acoustic thresholds for impulsive sounds (such
as HRG survey equipment) contained in the Technical Guidance (NMFS,
2018) were presented as dual metric acoustic thresholds using both
cumulative sound exposure level (SELcum) and peak sound
pressure level metrics. As dual metrics, NMFS considers onset of PTS
(Level A harassment) to have occurred when either one of the two
metrics is exceeded (i.e., the metric resulting in the largest
isopleth). The SELcum metric considers both level and
duration of exposure, as well as auditory weighting functions by marine
mammal hearing group.
Modeling of distances to isopleths corresponding to the Level A
harassment threshold was performed for all types of HRG equipment
proposed for use with the potential to result in harassment of marine
mammals. Mayflower used a new model developed by JASCO to calculate
distances to Level A harassment isopleths based on both the peak SPL
and the SELcum metric. For the peak SPL metric, the model is
a series of equations that accounts for both seawater absorption and
HRG equipment beam patterns (for all HRG sources with beam widths
larger than 90[deg], it was assumed these sources were
omnidirectional). For the SELcum metric, a model was
developed that accounts for the hearing sensitivity of the marine
mammal group, seawater absorption, and beam width for downwards-facing
transducers. Details of the modeling methodology for both the peak SPL
and SELcum metrics are provided in Appendix A of the IHA
application. This model entails the following steps:
1. Weighted broadband source levels were calculated by assuming a
flat spectrum between the source minimum and maximum frequency,
weighted the spectrum according to the marine mammal hearing group
weighting function (NMFS 2018), and summed across frequency;
2. Propagation loss was modeled as a function of oblique range;
3. Per-pulse SEL was modeled for a stationary receiver at a fixed
distance off a straight survey line, using a vessel transit speed of
3.5 knots and source-specific pulse length and repetition rate. The
off-line distance is referred to as the closest point of approach (CPA)
and was performed for CPA distances between 1 m and 10 km. The survey
line length was modeled as 10 km long (analysis showed longer survey
lines increased SEL by a negligible amount). SEL is calculated as SPL +
10 log10 T/15 dB, where T is the pulse duration;
4. The SEL for each survey line was calculated to produce curves of
weighted SEL as a function of CPA distance; and
5. The curves from Step 4 above were used to estimate the CPA
distance to the impact criteria.
We note that in the modeling methods described above and in
Appendix A of the IHA application, sources that operate with a
repetition rate greater than 10 Hz were assessed with the non-impulsive
(intermittent) source criteria while sources with a repetition rate
equal to or less than 10 Hz were assessed with the impulsive source
criteria. NMFS does not necessarily agree with this step in the
modeling assessment, which results in nearly all HRG sources being
classified as impulsive; however, we note that the classification of
the majority of HRG sources as impulsive results in more conservative
modeling results. Thus, we have assessed the potential for Level A
harassment to result from the proposed activities based on the modeled
Level A zones with the acknowledgement that these zones are likely
conservative.
Modeled isopleth distances to Level A harassment thresholds for all
types of HRG equipment and all marine mammal functional hearing groups
are shown in Table 6. The dual criteria (peak SPL and
SELcum) were applied to all HRG sources using the modeling
methodology as described above, and the largest isopleth distances for
each functional hearing group were then carried forward in the exposure
analysis to be conservative. For all HRG sources, the SELcum
metric resulted in larger isopleth distances. Distances to the Level A
harassment threshold based on the larger of the dual criteria (peak SPL
and SELcum) are shown in Table 6.
Modeled distances to isopleths corresponding to the Level A
harassment threshold are very small (<1 m) for three of the four marine
mammal functional hearing groups that may be impacted by the proposed
activities (i.e., low frequency and mid frequency cetaceans, and phocid
pinnipeds; see Table 6). Based on the very small Level A harassment
zones for these functional hearing groups, the potential for species
within these functional hearing groups to be taken by Level A
harassment is considered so low as to be discountable. For harbor
porpoises (a high frequency specialist), the largest modeled distance
to the Level A harassment threshold for the high frequency functional
hearing group was 60 m (Table 6). However, as noted above, modeled
distances to isopleths corresponding to the Level A harassment
threshold are assumed to be conservative. Further, the Innomar source
uses a very narrow beam width (two degrees) and the distances to the
Level A harassment isopleths are eight meters or less for the other two
sources. Level A harassment would also be more likely to occur at close
approach to the sound source or as a result of longer duration exposure
to the sound source, and mitigation measures--including a 100-m
exclusion zone for harbor porpoises--are expected to minimize the
potential for close approach or longer duration exposure to active HRG
[[Page 31874]]
sources. In addition, harbor porpoises are a notoriously shy species
which is known to avoid vessels, and would also be expected to avoid a
sound source prior to that source reaching a level that would result in
injury (Level A harassment). Therefore, we have determined that the
potential for take by Level A harassment of harbor porpoises is so low
as to be discountable. As NMFS has determined that the likelihood of
take of any marine mammals in the form of Level A harassment occurring
as a result of the proposed surveys is so low as to be discountable, we
therefore do not propose to authorize the take by Level A harassment of
any marine mammals.
Marine Mammal Occurrence
In this section we provide the information about the presence,
density, or group dynamics of marine mammals that will inform the take
calculations.
The habitat-based density models produced by the Duke University
Marine Geospatial Ecology Laboratory (Roberts et al., 2016, 2017, 2018)
represent the best available information regarding marine mammal
densities in the proposed survey area. The density data presented by
Roberts et al. (2016, 2017, 2018) incorporates aerial and shipboard
line-transect survey data from NMFS and other organizations and
incorporates data from 8 physiographic and 16 dynamic oceanographic and
biological covariates, and controls for the influence of sea state,
group size, availability bias, and perception bias on the probability
of making a sighting. These density models were originally developed
for all cetacean taxa in the U.S. Atlantic (Roberts et al., 2016). In
subsequent years, certain models have been updated on the basis of
additional data as well as certain methodological improvements. Our
evaluation of the changes leads to a conclusion that these represent
the best scientific evidence available. More information, including the
model results and supplementary information for each model, is
available online at seamap.env.duke.edu/models/Duke-EC-GOM-2015/.
Marine mammal density estimates in the project area (animals/km\2\)
were obtained using these model results (Roberts et al., 2016, 2017,
2018). The updated models incorporate additional sighting data,
including sightings from the NOAA Atlantic Marine Assessment Program
for Protected Species (AMAPPS) surveys from 2010-2014 (NEFSC & SEFSC,
2011, 2012, 2014a, 2014b, 2015, 2016).
For the exposure analysis, density data from Roberts et al. (2016,
2017, 2018) were mapped using a geographic information system (GIS).
These data provide abundance estimates for species or species guilds
within 10 km x 10 km grid cells (100 km\2\) on a monthly or annual
basis, depending on the species. In order to select a representative
sample of grid cells in and near the Project Area, a 10-km wide
perimeter around the Lease Area and an 8-km wide perimeter around the
cable route were created in GIS (ESRI 2017). The perimeters were then
used to select grid cells near the Project Area containing the most
recent monthly or annual estimates for each species in the Roberts et
al. (2016, 2017, 2018) data. The average monthly abundance for each
species in each survey area (deep-water and shallow-water) was
calculated as the mean value of the grid cells within each survey
portion in each month (June through September), and then converted for
density (individuals/km\2\) by dividing by 100 km\2\ (Tables 7 and 8).
Roberts et al. (2018) produced density models for all seals and did
not differentiate by seal species. Because the seasonality and habitat
use by gray seals roughly overlaps with that of harbor seals in the
survey areas, it was assumed that modeled takes of seals could occur to
either of the respective species, thus the total number of modeled
takes for seals was applied to each species.
Table 7--Average Monthly Densities for Species in the Lease Area and Deep-Water Section of the Cable Route
----------------------------------------------------------------------------------------------------------------
Estimated monthly density (individuals/km2)
Species ---------------------------------------------------------------
June July August September
----------------------------------------------------------------------------------------------------------------
Fin whale....................................... 0.0032 0.0033 0.0029 0.0025
Humpback whale.................................. 0.0014 0.0011 0.0005 0.0011
Minke whale..................................... 0.0024 0.0010 0.0007 0.0008
North Atlantic right whale...................... 0.0012 0.0000 0.0000 0.0000
Sei whale....................................... 0.0002 0.0001 0.0000 0.0001
Atlantic white-sided dolphin.................... 0.0628 0.0446 0.0243 0.0246
Bottlenose dolphin.............................. 0.0249 0.0516 0.0396 0.0494
Harbor porpoise................................. 0.0188 0.0125 0.0114 0.0093
Pilot whale..................................... 0.0066 0.0066 0.0066 0.0066
Risso's dolphin................................. 0.0002 0.0005 0.0009 0.0007
Common dolphin.................................. 0.0556 0.0614 0.1069 0.1711
Sperm whale..................................... 0.0001 0.0004 0.0004 0.0002
Seals (harbor and gray)......................... 0.0260 0.0061 0.0033 0.0040
----------------------------------------------------------------------------------------------------------------
Table 8--Average Monthly Densities for Species in the Shallow-Water Section of the Cable Route
----------------------------------------------------------------------------------------------------------------
Estimated monthly density (individuals/km\2\)
Species ---------------------------------------------------------------
June July August September
----------------------------------------------------------------------------------------------------------------
Fin whale....................................... 0.0003 0.0003 0.0003 0.0003
Humpback whale.................................. 0.0001 0.0001 0.0000 0.0001
Minke whale..................................... 0.0002 0.0000 0.0000 0.0000
North Atlantic right whale...................... 0.0000 0.0000 0.0000 0.0000
Sei whale....................................... 0.0000 0.0000 0.0000 0.0000
Atlantic white-sided dolphin.................... 0.0010 0.0006 0.0005 0.0008
Bottlenose dolphin.............................. 0.2308 0.4199 0.3211 0.3077
Harbor porpoise................................. 0.0048 0.0023 0.0037 0.0036
[[Page 31875]]
Pilot whale..................................... 0.0000 0.0000 0.0000 0.0000
Risso's dolphin................................. 0.0000 0.0000 0.0000 0.0000
Common dolphin.................................. 0.0003 0.0002 0.0006 0.0009
Sperm whale..................................... 0.0000 0.0000 0.0000 0.0000
Seals (harbor and gray)......................... 0.2496 0.0281 0.0120 0.0245
----------------------------------------------------------------------------------------------------------------
Take Calculation and Estimation
Here we describe how the information provided above is brought
together to produce a quantitative take estimate.
In order to estimate the number of marine mammals predicted to be
exposed to sound levels that would result in harassment, radial
distances to predicted isopleths corresponding to harassment thresholds
are calculated, as described above. Those distances are then used to
calculate the area(s) around the HRG survey equipment predicted to be
ensonified to sound levels that exceed harassment thresholds. The area
estimated to be ensonified to relevant thresholds in a single day is
then calculated, based on areas predicted to be ensonified around the
HRG survey equipment and the estimated trackline distance traveled per
day by the survey vessel. Mayflower estimates that the proposed survey
vessel in the Lease Area and deep-water sections of the cable route
will achieve a maximum daily trackline of 110 km per day and the
proposed survey vessels in the shallow-water section of the cable route
will achieve a maximum of 55 km per day during proposed HRG surveys.
This distance accounts for survey vessels traveling at roughly 3 knots
and accounts for non-active survey periods.
Based on the maximum estimated distance to the Level B harassment
threshold of 141 m (Table 6) and the maximum estimated daily track line
distance of 110 km, an area of 31.1 km\2\ would be ensonified to the
Level B harassment threshold each day in the Lease Area and deep-water
section of the cable route during Mayflower's proposed surveys. During
90 days of anticipated survey activity over the four month period (June
through September), approximately 22.5 days of survey activity are
expected each month, for an average of 699.4 km\2\ ensonified to the
Level B harassment threshold in the Lease Area and deep-water section
of the cable route each month of survey activities.
Similarly, based on the maximum estimated distance to the Level B
harassment threshold of 141 m (Table 6) and the maximum estimated daily
track line distance of 55 km, an area of 15.6 km\2\ would be ensonified
to the Level B harassment threshold each day in the shallow-water
section of the cable route. During 125 days of anticipated survey
activity over the four month period (June through September),
approximately 31.3 days of survey activity (split among two vessels)
are expected each month, for an average of 486.6 km\2\ ensonified to
the Level B harassment threshold in the shallow-water section of the
cable route each month of survey activities.
As described above, this is a conservative estimate as it assumes
the HRG sources that result in the greatest isopleth distances to the
Level B harassment threshold would be operated at all times during all
215 vessel days.
The estimated numbers of marine mammals that may be taken by Level
B harassment were calculated by multiplying the monthly density for
each species in each survey area (Table 7 and 8) by the respective
monthly ensonified area within each survey section. The results were
then summed to determine the total estimated take (Table 9).
Table 9--Numbers of Potential Incidental Take of Marine Mammals Proposed for Authorization and Proposed Takes as a Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Calculated take by survey
region Total Total proposed
-------------------------------- calculated Proposed takes Proposed takes instances of
Species Lease area and takes by by level A by level B take as a
deep-water Shallow-water level B harassment harassment \b\ percentage of
cable route cable route harassment population \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale............................................... 8.3 0.6 8.9 0 9 0.3
Humpback whale.......................................... 2.9 0.2 3.1 0 4 0.2
Minke whale............................................. 3.4 0.2 3.6 0 4 0.1
North Atlantic right whale.............................. 0.9 0 0.9 0 \c\ 3 0.8
Sei whale............................................... 0.3 0 0.3 0 \c\ 2 0.4
Atlantic white-sided dolphin............................ 109.3 1.4 110.7 0 111 0.1
Bottlenose dolphin...................................... 115.7 622.6 738.3 0 739 1.0
Harbor porpoise......................................... 36.4 7 43.4 0 44 0.1
Pilot whale............................................. 18.4 0 18.4 0 19 0.1
Risso's dolphin......................................... 1.7 0 1.7 0 \b\ 6 0.1
Common dolphin.......................................... 276.3 1 277.2 0 278 0.2
Sperm whale............................................. 0.8 0 0.8 0 \c\ 2 0.0
[[Page 31876]]
Seals (harbor and gray)................................. 40.4 152.8 193.2 0 194 0.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Calculations of percentage of stock taken are based on the best available abundance estimate as shown in Table 3. In most cases the best available
abundance estimate is provided by Roberts et al. (2016, 2017, 2018), when available, to maintain consistency with density estimates derived from
Roberts et al. (2016, 2017, 2018). For bottlenose dolphins and seals, Roberts et al. (2016, 2017, 2018) provides only a single abundance estimate and
does not provide abundance estimates at the stock or species level (respectively), so the abundance estimate used to estimate percentage of stock
taken for bottlenose dolphins is derived from NMFS SARs (Hayes et al., 2019). For seals, NMFS proposes to authorize 194 takes of seals as a guild by
Level B harassment and assumes take could occur to either species. For the purposes of estimating percentage of stock taken, the NMFS SARs abundance
estimate for gray seals was used as the abundance of gray seals is lower than that of harbor seals (Hayes et al., 2019).
\b\ Proposed take equal to calculated take rounded up to next integer, or mean group size.
\c\ Proposed take increased to mean group size (Palka et al., 2017; Kraus et al., 2016).
Using the take methodology approach described above, the take
estimates for Risso's dolphin, sei whale, North Atlantic right whale,
and sperm whale were less than the average group sizes estimated for
these species (Table 9). However, information on the social structures
of these species indicates these species are likely to be encountered
in groups. Therefore it is reasonable to conservatively assume that one
group of each of these species will be taken during the proposed
survey. We therefore propose to authorize the take of the average group
size for these species to account for the possibility that the proposed
survey encounters a group of either of these species (Table 9).
As described above, NMFS has determined that the likelihood of take
of any marine mammals in the form of Level A harassment occurring as a
result of the proposed surveys is so low as to be discountable;
therefore, we do not propose to authorize take of any marine mammals by
Level A harassment.
Proposed Mitigation
In order to issue an IHA under Section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, we
carefully consider two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned), and;
(2) the practicability of the measures for applicant
implementation, which may consider such things as cost, impact on
operations, and, in the case of a military readiness activity,
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
Proposed Mitigation Measures
NMFS proposes the following mitigation measures be implemented
during Mayflower's proposed marine site characterization surveys.
Marine Mammal Exclusion Zones, Buffer Zone and Monitoring Zone
Marine mammal exclusion zones (EZ) would be established around the
HRG survey equipment and monitored by protected species observers (PSO)
during HRG surveys as follows:
A 500-m EZ would be required for North Atlantic right
whales; and
A 100-m EZ would be required for all other marine mammals
(with the exception of certain small dolphin species specified below).
If a marine mammal is detected approaching or entering the EZs
during the proposed survey, the vessel operator would adhere to the
shutdown procedures described below. In addition to the EZs described
above, PSOs would visually monitor a 200 m Buffer Zone. During use of
acoustic sources with the potential to result in marine mammal
harassment (i.e., anytime the acoustic source is active, including
ramp-up), occurrences of marine mammals within the Buffer Zone (but
outside the EZs) would be communicated to the vessel operator to
prepare for potential shutdown of the acoustic source. The Buffer Zone
is not applicable when the EZ is greater than 100 meters. PSOs would
also be required to observe a 500-m Monitoring Zone and record the
presence of all marine mammals within this zone. In addition, any
marine mammals observed within 141 m of the active HRG equipment
operating at or below 180 kHz would be documented by PSOs as taken by
Level B harassment. The zones described above would be based upon the
radial distance from the active equipment (rather than being based on
distance from the vessel itself).
Visual Monitoring
A minimum of one NMFS-approved PSO must be on duty and conducting
visual observations at all times during daylight hours (i.e., from 30
minutes prior to sunrise through 30 minutes following sunset) and 30
minutes prior
[[Page 31877]]
to and during nighttime ramp-ups of HRG equipment. Visual monitoring
would begin no less than 30 minutes prior to ramp-up of HRG equipment
and would continue until 30 minutes after use of the acoustic source
ceases or until 30 minutes past sunset. PSOs would establish and
monitor the applicable EZs, Buffer Zone and Monitoring Zone as
described above. Visual PSOs would coordinate to ensure 360[deg] visual
coverage around the vessel from the most appropriate observation posts,
and would conduct visual observations using binoculars and the naked
eye while free from distractions and in a consistent, systematic, and
diligent manner. PSOs would estimate distances to marine mammals
located in proximity to the vessel and/or relevant using range finders.
It would be the responsibility of the Lead PSO on duty to communicate
the presence of marine mammals as well as to communicate and enforce
the action(s) that are necessary to ensure mitigation and monitoring
requirements are implemented as appropriate. Position data would be
recorded using hand-held or vessel global positioning system (GPS)
units for each confirmed marine mammal sighting.
Pre-Clearance of the Exclusion Zones
Prior to initiating HRG survey activities, Mayflower would
implement a 30-minute pre-clearance period. During pre-clearance
monitoring (i.e., before ramp-up of HRG equipment begins), the Buffer
Zone would also act as an extension of the 100-m EZ in that
observations of marine mammals within the 200-m Buffer Zone would also
preclude HRG operations from beginning. During this period, PSOs would
ensure that no marine mammals are observed within 200 m of the survey
equipment (500 m in the case of North Atlantic right whales). HRG
equipment would not start up until this 200-m zone (or, 500-m zone in
the case of North Atlantic right whales) is clear of marine mammals for
at least 30 minutes. The vessel operator would notify a designated PSO
of the proposed start of HRG survey equipment as agreed upon with the
lead PSO; the notification time should not be less than 30 minutes
prior to the planned initiation of HRG equipment order to allow the
PSOs time to monitor the EZs and Buffer Zone for the 30 minutes of pre-
clearance. A PSO conducting pre-clearance observations would be
notified again immediately prior to initiating active HRG sources.
If a marine mammal were observed within the relevant EZs or Buffer
Zone during the pre-clearance period, initiation of HRG survey
equipment would not begin until the animal(s) has been observed exiting
the respective EZ or Buffer Zone, or, until an additional time period
has elapsed with no further sighting (i.e., minimum 15 minutes for
small odontocetes and seals, and 30 minutes for all other species). The
pre-clearance requirement would include small delphinoids that approach
the vessel (e.g., bow ride). PSOs would also continue to monitor the
zone for 30 minutes after survey equipment is shut down or survey
activity has concluded.
Ramp-Up of Survey Equipment
When technically feasible, a ramp-up procedure would be used for
geophysical survey equipment capable of adjusting energy levels at the
start or re-start of survey activities. The ramp-up procedure would be
used at the beginning of HRG survey activities in order to provide
additional protection to marine mammals near the Project Area by
allowing them to detect the presence of the survey and vacate the area
prior to the commencement of survey equipment operation at full power.
Ramp-up of the survey equipment would not begin until the relevant EZs
and Buffer Zone has been cleared by the PSOs, as described above. HRG
equipment would be initiated at their lowest power output and would be
incrementally increased to full power. If any marine mammals are
detected within the EZs or Buffer Zone prior to or during ramp-up, the
HRG equipment would be shut down (as described below).
Shutdown Procedures
If an HRG source is active and a marine mammal is observed within
or entering a relevant EZ (as described above) an immediate shutdown of
the HRG survey equipment would be required. When shutdown is called for
by a PSO, the acoustic source would be immediately deactivated and any
dispute resolved only following deactivation. Any PSO on duty would
have the authority to delay the start of survey operations or to call
for shutdown of the acoustic source if a marine mammal is detected
within the applicable EZ. The vessel operator would establish and
maintain clear lines of communication directly between PSOs on duty and
crew controlling the HRG source(s) to ensure that shutdown commands are
conveyed swiftly while allowing PSOs to maintain watch. Subsequent
restart of the HRG equipment would only occur after the marine mammal
has either been observed exiting the relevant EZ, or, until an
additional time period has elapsed with no further sighting of the
animal within the relevant EZ (i.e., 15 minutes for small odontocetes
and seals, and 30 minutes for large whales).
Upon implementation of shutdown, the HRG source may be reactivated
after the marine mammal that triggered the shutdown has been observed
exiting the applicable EZ (i.e., the animal is not required to fully
exit the Buffer Zone where applicable) or, following a clearance period
of 15 minutes for small odontocetes and seals and 30 minutes for all
other species with no further observation of the marine mammal(s)
within the relevant EZ. If the HRG equipment shuts down for brief
periods (i.e., less than 30 minutes) for reasons other than mitigation
(e.g., mechanical or electronic failure) the equipment may be re-
activated as soon as is practicable at full operational level, without
30 minutes of pre-clearance, only if PSOs have maintained constant
visual observation during the shutdown and no visual detections of
marine mammals occurred within the applicable EZs and Buffer Zone
during that time. For a shutdown of 30 minutes or longer, or if visual
observation was not continued diligently during the pause, pre-
clearance observation is required, as described above.
The shutdown requirement would be waived for certain genera of
small delphinids (i.e., Delphinus, Lagenorhynchus, and Tursiops) under
certain circumstances. If a delphinid(s) from these genera is visually
detected approaching the vessel (i.e., to bow ride) or towed survey
equipment, shutdown would not be required. If there is uncertainty
regarding identification of a marine mammal species (i.e., whether the
observed marine mammal(s) belongs to one of the delphinid genera for
which shutdown is waived), PSOs would use best professional judgment in
making the decision to call for a shutdown.
If a species for which authorization has not been granted, or, a
species for which authorization has been granted but the authorized
number of takes have been met, approaches or is observed within the
area encompassing the Level B harassment isopleth (141 m), shutdown
would occur.
Vessel Strike Avoidance
Vessel strike avoidance measures would include, but would not be
limited to, the following, except under circumstances when complying
with these requirements would put the safety of the vessel or crew at
risk:
All vessel operators and crew will maintain vigilant watch
for cetaceans and pinnipeds, and slow down or stop their vessel to
avoid striking these protected species;
[[Page 31878]]
All survey vessels, regardless of size, must observe a 10-
knot speed restriction in DMAs designated by NMFS for the protection of
North Atlantic right whales from vessel strikes. Note that this
requirement includes vessels, regardless of size, to adhere to a 10
knot speed limit in DMAs, not just vessels 65 ft or greater in length;
All vessel operators will reduce vessel speed to 10 knots
(18.5 km/hr) or less when any large whale, any mother/calf pairs, large
assemblages of non-delphinoid cetaceans are observed near (within 100 m
(330 ft)) an underway vessel;
All vessels will maintain a separation distance of 500 m
(1,640 ft) or greater from any sighted North Atlantic right whale;
If underway, vessels must steer a course away from any
sighted North Atlantic right whale at 10 knots (18.5 km/hr) or less
until the 500-m (1,640 ft) minimum separation distance has been
established. If a North Atlantic right whale is sighted in a vessel's
path, or within 100 m (330 ft) to an underway vessel, the underway
vessel must reduce speed and shift the engine to neutral. Engines will
not be engaged until the North Atlantic right whale has moved outside
of the vessel's path and beyond 100 m. If stationary, the vessel must
not engage engines until the North Atlantic right whale has moved
beyond 100 m;
All vessels will maintain a separation distance of 100 m
(330 ft) or greater from any sighted non-delphinoid cetacean. If
sighted, the vessel underway must reduce speed and shift the engine to
neutral, and must not engage the engines until the non-delphinoid
cetacean has moved outside of the vessel's path and beyond 100 m. If a
survey vessel is stationary, the vessel will not engage engines until
the non-delphinoid cetacean has moved out of the vessel's path and
beyond 100 m;
All vessels will maintain a separation distance of 50 m
(164 ft) or greater from any sighted delphinoid cetacean. Any vessel
underway remain parallel to a sighted delphinoid cetacean's course
whenever possible, and avoid excessive speed or abrupt changes in
direction. Any vessel underway reduces vessel speed to 10 knots (18.5
km/hr) or less when pods (including mother/calf pairs) or large
assemblages of delphinoid cetaceans are observed. Vessels may not
adjust course and speed until the delphinoid cetaceans have moved
beyond 50 m and/or the abeam of the underway vessel;
All vessels will maintain a separation distance of 50 m
(164 ft) or greater from any sighted pinniped; and
All vessels underway will not divert or alter course in
order to approach any whale, delphinoid cetacean, or pinniped. Any
vessel underway will avoid excessive speed or abrupt changes in
direction to avoid injury to the sighted cetacean or pinniped.
Project-specific training will be conducted for all vessel crew
prior to the start of survey activities. Confirmation of the training
and understanding of the requirements will be documented on a training
course log sheet. Signing the log sheet will certify that the crew
members understand and will comply with the necessary requirements
throughout the survey activities.
Passive Acoustic Monitoring
Vineyard Wind would also employ passive acoustic monitoring (PAM)
to support monitoring during night time operations to provide for
acquisition of species detections at night. While PAM is not typically
required by NMFS for HRG surveys, it may a provide additional benefit
as a mitigation and monitoring measure to further limit potential
exposure to underwater sound at levels that could result in injury or
behavioral harassment.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS, NMFS has preliminarily
determined that the proposed mitigation measures provide the means
effecting the least practicable impact on the affected species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, Section 101(a)(5)(D) of
the MMPA states that 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
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 in the
proposed action area. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) Action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the action; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
How anticipated responses to stressors impact either: (1)
Long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
Mitigation and monitoring effectiveness.
Proposed Monitoring Measures
As described above, visual monitoring would be performed by
qualified and NMFS-approved PSOs. Mayflower would use independent,
dedicated, trained PSOs, meaning that the PSOs must be employed by a
third-party observer provider, must have no tasks other than to conduct
observational effort, collect data, and communicate with and instruct
relevant vessel crew with regard to the presence of marine mammals and
mitigation requirements (including brief alerts regarding maritime
hazards), and must have successfully completed an approved PSO training
course appropriate for their designated task. Mayflower would provide
resumes of all proposed PSOs (including alternates) to NMFS for review
and approval prior to the start of survey operations.
During survey operations (e.g., any day on which use of an HRG
source is planned to occur), a minimum of one PSO must be on duty and
conducting visual observations at all times on all active survey
vessels during daylight
[[Page 31879]]
hours (i.e., from 30 minutes prior to sunrise through 30 minutes
following sunset) and nighttime ramp-ups of HRG equipment. Visual
monitoring would begin no less than 30 minutes prior to initiation of
HRG survey equipment and would continue until one hour after use of the
acoustic source ceases or until 30 minutes past sunset. PSOs would
coordinate to ensure 360[deg] visual coverage around the vessel from
the most appropriate observation posts, and would conduct visual
observations using binoculars and the naked eye while free from
distractions and in a consistent, systematic, and diligent manner. PSOs
may be on watch for a maximum of four consecutive hours followed by a
break of at least two hours between watches and may conduct a maximum
of 12 hours of observation per 24-hour period. In cases where multiple
vessels are surveying concurrently, any observations of marine mammals
would be communicated to PSOs on all survey vessels.
PSOs would be equipped with binoculars and have the ability to
estimate distances to marine mammals located in proximity to the vessel
and/or exclusion zone using range finders. Reticulated binoculars will
also be available to PSOs for use as appropriate based on conditions
and visibility to support the monitoring of marine mammals. Position
data would be recorded using hand-held or vessel GPS units for each
sighting. Observations would take place from the highest available
vantage point on the survey vessel. General 360-degree scanning would
occur during the monitoring periods, and target scanning by the PSO
would occur when alerted of a marine mammal presence.
During good conditions (e.g., daylight hours; Beaufort sea state
(BSS) 3 or less), to the maximum extent practicable, PSOs would conduct
observations when the acoustic source is not operating for comparison
of sighting rates and behavior with and without use of the acoustic
source and between acquisition periods. Any observations of marine
mammals by crew members aboard any vessel associated with the survey
would be relayed to the PSO team.
Data on all PSO observations would be recorded based on standard
PSO collection requirements. This would include dates, times, and
locations of survey operations; dates and times of observations,
location and weather; details of marine mammal sightings (e.g.,
species, numbers, behavior); and details of any observed marine mammal
take that occurs (e.g., noted behavioral disturbances).
Proposed Reporting Measures
Within 90 days after completion of survey activities, a final
technical report will be provided to NMFS that fully documents the
methods and monitoring protocols, summarizes the data recorded during
monitoring, summarizes the number of marine mammals estimated to have
been taken during survey activities (by species, when known),
summarizes the mitigation actions taken during surveys (including what
type of mitigation and the species and number of animals that prompted
the mitigation action, when known), and provides an interpretation of
the results and effectiveness of all mitigation and monitoring. Any
recommendations made by NMFS must be addressed in the final report
prior to acceptance by NMFS.
In addition to the final technical report, Mayflower will provide
the reports described below as necessary during survey activities. In
the unanticipated event that Mayflower's activities lead to an injury
(Level A harassment) of a marine mammal, Mayflower would immediately
cease the specified activities and report the incident to the NMFS
Office of Protected Resources Permits and Conservation Division and the
NMFS Northeast Regional Stranding Coordinator. The report would include
the following information:
Time, date, and location (latitude/longitude) of the
incident;
Name and type of vessel involved;
Vessel's speed during and leading up to the incident;
Description of the incident;
Status of all sound source use in the 24 hours preceding
the incident;
Water depth;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, and visibility);
Description of all marine mammal observations in the 24
hours preceding the incident;
Species identification or description of the animal(s)
involved;
Fate of the animal(s); and
Photographs or video footage of the animal(s) (if
equipment is available).
Activities would not resume until NMFS is able to review the
circumstances of the event. NMFS would work with Mayflower to minimize
reoccurrence of such an event in the future. Mayflower would not resume
activities until notified by NMFS.
In the event that Mayflower personnel discover an injured or dead
marine mammal, Mayflower would report the incident to the OPR Permits
and Conservation Division and the NMFS Northeast Regional Stranding
Coordinator as soon as feasible. The report would include the following
information:
Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
Species identification (if known) or description of the
animal(s) involved;
Condition of the animal(s) (including carcass condition if
the animal is dead);
Observed behaviors of the animal(s), if alive;
If available, photographs or video footage of the
animal(s); and
General circumstances under which the animal was
discovered.
In the unanticipated event of a ship strike of a marine mammal by
any vessel involved in the activities covered by the IHA, Mayflower
would report the incident to the NMFS OPR Permits and Conservation
Division and the NMFS Northeast Regional Stranding Coordinator as soon
as feasible. The report would include the following information:
Time, date, and location (latitude/longitude) of the
incident;
Species identification (if known) or description of the
animal(s) involved;
Vessel's speed during and leading up to the incident;
Vessel's course/heading and what operations were being
conducted (if applicable);
Status of all sound sources in use;
Description of avoidance measures/requirements that were
in place at the time of the strike and what additional measures were
taken, if any, to avoid strike;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, visibility) immediately preceding the
strike;
Estimated size and length of animal that was struck;
Description of the behavior of the marine mammal
immediately preceding and following the strike;
If available, description of the presence and behavior of
any other marine mammals immediately preceding the strike;
Estimated fate of the animal (e.g., dead, injured but
alive, injured and moving, blood or tissue observed in the water,
status unknown, disappeared); and
To the extent practicable, photographs or video footage of
the animal(s).
[[Page 31880]]
Negligible Impact Analysis and Determination
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'' through harassment, 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's 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, ongoing sources of human-caused mortality, or
ambient noise levels).
To avoid repetition, our analysis applies to all the species listed
in Table 3, given that NMFS expects the anticipated effects of the
proposed survey to be similar in nature. NMFS does not anticipate that
serious injury or mortality would result from HRG surveys, even in the
absence of mitigation, and no serious injury or mortality is
authorized. As discussed in the Potential Effects section, non-auditory
physical effects and vessel strike are not expected to occur. We expect
that potential takes would be in the form of short-term Level B
behavioral harassment in the form of temporary avoidance of the area or
decreased foraging (if such activity were occurring), reactions that
are considered to be of low severity and with no lasting biological
consequences (e.g., Southall et al., 2007). As described above, Level A
harassment is not expected to result given the nature of the
operations, the anticipated size of the Level A harassment zones, the
density of marine mammals in the area, and the required shutdown zones.
Effects on individuals that are taken by Level B harassment, on the
basis of reports in the literature as well as monitoring from other
similar activities, will likely be limited to reactions such as
increased swimming speeds, increased surfacing time, or decreased
foraging (if such activity were occurring). Most likely, individuals
will simply move away from the sound source and temporarily avoid the
area where the survey is occurring. We expect that any avoidance of the
survey area by marine mammals would be temporary in nature and that any
marine mammals that avoid the survey area during the survey activities
would not be permanently displaced. Even repeated Level B harassment of
some small subset of an overall stock is unlikely to result in any
significant realized decrease in viability for the affected
individuals, and thus would not result in any adverse impact to the
stock as a whole.
Regarding impacts to marine mammal habitat, prey species are
mobile, and are broadly distributed throughout the Project Area and the
footprint of the activity is small; therefore, marine mammals that may
be temporarily displaced during survey activities are expected to be
able to resume foraging once they have moved away from areas with
disturbing levels of underwater noise. Because of the availability of
similar habitat and resources in the surrounding area the impacts to
marine mammals and the food sources that they utilize are not expected
to cause significant or long-term consequences for individual marine
mammals or their populations. The HRG survey equipment itself will not
result in physical habitat disturbance. Avoidance of the area around
the HRG survey activities by marine mammal prey species is possible.
However, any avoidance by prey species would be expected to be short
term and temporary.
ESA-listed species for which takes are authorized are North
Atlantic right, fin, sei, and sperm whales, and these effects are
anticipated to be limited to lower level behavioral effects. The
proposed survey is not anticipated to affect the fitness or
reproductive success of individual animals. Since impacts to individual
survivorship and fecundity are unlikely, the proposed survey is not
expected to result in population-level effects for any ESA-listed
species or alter current population trends of any ESA-listed species.
The status of the North Atlantic right whale population is of
heightened concern and, therefore, merits additional analysis. NMFS has
rigorously assessed potential impacts to right whales from this survey.
We have established a 500-m shutdown zone for right whales which is
precautionary considering the Level B harassment isopleth for the
largest source utilized (i.e., GeoMarine Geo-Source 400 tip sparker) is
estimated to be 141 m.
The proposed Project Area encompasses or is in close proximity to
feeding BIAs for right whales (February-April), humpback whales (March-
December), fin whales (March-October), and sei whales (May-November) as
well as a migratory BIA for right whales (March-April and November-
December. Most of these feeding BIAs are extensive and sufficiently
large (705 km\2\ and 3,149 km\2\ for right whales; 47,701 km\2\ for
humpback whales; 2,933 km\2\ for fin whales; and 56,609 km\2\ for sei
whales), and the acoustic footprint of the proposed survey is
sufficiently small, that feeding opportunities for these whales would
not be reduced appreciably. Any whales temporarily displaced from the
proposed Project Area would be expected to have sufficient remaining
feeding habitat available to them, and would not be prevented from
feeding in other areas within the biologically important feeding
habitat. In addition, any displacement of whales from the BIA or
interruption of foraging bouts would be expected to be temporary in
nature. Therefore, we do not expect impacts to whales within feeding
BIAs to to effect the fitness of any large whales.
A migratory BIA for North Atlantic right whales (effective March-
April and November-December) extends from Massachusetts to Florida
(LaBrecque, et al., 2015). Off the south coast of Massachusetts and
Rhode Island, this BIA extends from the coast to beyond the shelf
break. The fact that the spatial acoustic footprint of the proposed
survey is very small relative to the spatial extent of the available
migratory habitat means that right whale migration is not expected to
be impacted by the proposed survey. Required vessel strike avoidance
measures will also decrease risk of ship strike during migration. NMFS
is expanding the standard avoidance measures by requiring that all
vessels, regardless of size, adhere to a 10 knot speed limit in any
established DMAs. Additionally, limited take by Level B harassment of
North Atlantic right whales has been proposed as HRG survey operations
are required to shut down at 500 m to minimize the potential for
behavioral harassment of this species.
[[Page 31881]]
As noted previously, there are several active UMEs occurring in the
vicinity of Mayflower's proposed surveys. Elevated humpback whale
mortalities have occurred along the Atlantic coast from Maine through
Florida since January 2016. Of the cases examined, approximately half
had evidence of human interaction (ship strike or entanglement). The
UME does not yet provide cause for concern regarding population-level
impacts. Despite the UME, the relevant population of humpback whales
(the West Indies breeding population, or distinct population segment
(DPS)) remains stable. Beginning in January 2017, elevated minke whale
strandings have occurred along the Atlantic coast from Maine through
South Carolina, with highest numbers in Massachusetts, Maine, and New
York. This event does not provide cause for concern regarding
population level impacts, as the likely population abundance is greater
than 20,000 whales. Elevated North Atlantic right whale mortalities
began in June 2017, primarily in Canada. Overall, preliminary findings
support human interactions, specifically vessel strikes or rope
entanglements, as the cause of death for the majority of the right
whales. Elevated numbers of harbor seal and gray seal mortalities were
first observed in July 2018 and have occurred across Maine, New
Hampshire and Massachusetts. Based on tests conducted so far, the main
pathogen found in the seals is phocine distemper virus although
additional testing to identify other factors that may be involved in
this UME are underway. The UME does not yet provide cause for concern
regarding population-level impacts to any of these stocks. For harbor
seals, the population abundance is over 75,000 and annual M/SI (345) is
well below PBR (2,006) (Hayes et al., 2018). For gray seals, the
population abundance in the United States is over 27,000, with an
estimated abundance including seals in Canada of approximately 505,000,
and abundance is likely increasing in the U.S. Atlantic EEZ as well as
in Canada (Hayes et al., 2018).
Direct physical interactions (ship strikes and entanglements)
appear to be responsible for many of the UME humpback and right whale
mortalities recorded. The proposed HRG survey will require ship strike
avoidance measures which would minimize the risk of ship strikes while
fishing gear and in-water lines will not be employed as part of the
survey. Furthermore, the proposed activities are not expected to
promote the transmission of infectious disease among marine mammals.
The survey is not expected to result in the deaths of any marine
mammals or combine with the effects of the ongoing UMEs to result in
any additional impacts not analyzed here. Accordingly, Mayflower did
not request, and NMFS is not proposing to authorize, take of marine
mammals by serious injury, or mortality.
The required mitigation measures are expected to reduce the number
and/or severity of takes by giving animals the opportunity to move away
from the sound source before HRG survey equipment reaches full energy
and preventing animals from being exposed to sound levels that have the
potential to cause injury (Level A harassment) and more severe Level B
harassment during HRG survey activities, even in the biologically
important areas described above. No Level A harassment is anticipated
or authorized.
NMFS expects that takes would be in the form of short-term Level B
behavioral harassment in the form of brief startling reaction and/or
temporary vacating of the area, or decreased foraging (if such activity
were occurring)--reactions that (at the scale and intensity anticipated
here) are considered to be of low severity and with no lasting
biological consequences. Since both the source and the marine mammals
are mobile, only a smaller area would be ensonified by sound levels
that could result in take for only a short period. Additionally,
required mitigation measures would reduce exposure to sound that could
result in more severe behavioral harassment.
In summary and as described above, the following factors primarily
support our preliminary determination that the impacts resulting from
this activity are not expected to adversely affect the species or stock
through effects on annual rates of recruitment or survival:
No mortality or serious injury is anticipated or proposed
to be authorized;
No Level A harassment (PTS) is anticipated;
Any foraging interruptions are expected to be short term
and unlikely to be cause significantly impacts;
Impacts on marine mammal habitat and species that serve as
prey species for marine mammals are expected to be minimal and the
alternate areas of similar habitat value for marine mammals are readily
available;
Take is anticipated to be primarily Level B behavioral
harassment consisting of brief startling reactions and/or temporary
avoidance of the Project Area;
Survey activities would occur in such a comparatively
small portion of the biologically important area for north Atlantic
right whale migration, that any avoidance of the Project Area due to
activities would not affect migration. In addition, mitigation measures
to shut down at 500 m to minimize potential for Level B behavioral
harassment would limit both the number and severity of take of the
species;
Similarly, due to the relatively small footprint of the
survey activities in relation to the size of a biologically important
areas for right, humpback, fin, and sei whales foraging, the survey
activities would not affect foraging success of this species; and
Proposed mitigation measures, including visual monitoring
and shutdowns, are expected to minimize the intensity of potential
impacts to marine mammals.
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 Mayflower's proposed HRG surveys will have a
negligible impact on all affected marine mammal species or stocks.
Small Numbers
As noted above, only small numbers of incidental take may be
authorized under Sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. Additionally, other qualitative
factors may be considered in the analysis, such as the temporal or
spatial scale of the activities.
The numbers of marine mammals that we authorize to be taken, for
all species and stocks, would be considered small relative to the
relevant stocks or populations (less than one third of the best
available population abundance for all species and stocks) (see Table
9). In fact, the total amount of taking proposed for authorization for
all species is 1 percent or less for all affected stocks.
Based on the analysis contained herein of the proposed activity
(including the proposed mitigation and monitoring measures) and the
[[Page 31882]]
anticipated take of marine mammals, NMFS preliminarily finds that small
numbers of marine mammals will be taken relative to the population size
of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
Endangered Species Act (ESA)
Section 7(a)(2) of the Endangered Species Act of 1973 (16 U.S.C.
1531 et seq.) requires that each Federal agency insure that any action
it authorizes, funds, or carries out is not likely to jeopardize the
continued existence of any endangered or threatened species or result
in the destruction or adverse modification of designated critical
habitat. To ensure ESA compliance for the issuance of IHAs, NMFS
consults internally, in this case with the NMFS Greater Atlantic
Regional Fisheries Office (GARFO), whenever we propose to authorize
take for endangered or threatened species.
The NMFS Office of Protected Resources Permits and Conservation
Division is proposing to authorize the incidental take of four species
of marine mammals listed under the ESA: The North Atlantic right, fin,
sei, and sperm whale. The Permits and Conservation Division has
requested initiation of Section 7 consultation with NMFS GARFO for the
issuance of this IHA. NMFS will conclude the ESA section 7 consultation
prior to reaching a determination regarding the proposed issuance of
the authorization.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to Mayflower for conducting marine site characterization
surveys offshore of Massachusetts in the area of the Commercial Lease
of Submerged Lands for Renewable Energy Development on the Outer
Continental Shelf (OCS-A 0521) and along a potential submarine cable
route to landfall at Falmouth, Massachusetts for a period of one year
from the date of issuance, provided the previously mentioned
mitigation, monitoring, and reporting requirements are incorporated. A
draft of the proposed IHA can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
Request for Public Comments
We request comment on our analyses, the proposed authorization, and
any other aspect of this Notice of Proposed IHA for the proposed HRG
survey. We also request at this time comment on the potential Renewal
of this proposed IHA as described in the paragraph below. Please
include with your comments any supporting data or literature citations
to help inform decisions on the request for this IHA or a subsequent
Renewal IHA.
On a case-by-case basis, NMFS may issue a one-year Renewal IHA
following notice to the public providing an additional 15 days for
public comments when (1) up to another year of identical or nearly
identical, or nearly identical, activities as described in the
Specified Activities section of this notice is planned or (2) the
activities as described in the Specified Activities section of this
notice would not be completed by the time the IHA expires and a Renewal
would allow for completion of the activities beyond that described in
the Dates and Duration section of this notice, provided all of the
following conditions are met:
A request for renewal is received no later than 60 days
prior to the needed Renewal IHA effective date (recognizing that the
Renewal IHA expiration date cannot extend beyond one year from
expiration of the initial IHA);
The request for renewal must include the following:
(1) An explanation that the activities to be conducted under the
requested Renewal IHA are identical to the activities analyzed under
the initial IHA, are a subset of the activities, or include changes so
minor (e.g., reduction in pile size) that the changes do not affect the
previous analyses, mitigation and monitoring requirements, or take
estimates (with the exception of reducing the type or amount of take);
and
(2) A preliminary monitoring report showing the results of the
required monitoring to date and an explanation showing that the
monitoring results do not indicate impacts of a scale or nature not
previously analyzed or authorized; and
Upon review of the request for Renewal, the status of the
affected species or stocks, and any other pertinent information, NMFS
determines that there are no more than minor changes in the activities,
the mitigation and monitoring measures will remain the same and
appropriate, and the findings in the initial IHA remain valid.
Dated: May 19, 2020.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2020-11203 Filed 5-26-20; 8:45 am]
BILLING CODE 3510-22-P