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Size Matters: Examining the Effect of Body Size on Birth Rates in North Atlantic Right Whales

July 06, 2022

Recent research reveals that smaller female North Atlantic right whales produce fewer calves. Their body size has been declining in recent decades due to increased entanglements in fishing gear and other factors.

Photograph from the North Atlantic right whale Catalog #3560 of "Snow Cone," a North Atlantic right whale sighted December 2, 2021 that was entangled in gear and with a new calf. Photo credit: Florida Fish and Wildlife Conservation Commission taken under NOAA permit 20556. North Atlantic right whale Catalog #3560 ‘Snow Cone’ sighted December 2, 2021 entangled and with a new calf. Photo credit: Florida Fish and Wildlife Conservation Commission taken under NOAA permit 20556.

Editor's Note December 4, 2023: Endangered North Atlantic right whales are approaching extinction. There are approximately 360 individuals remaining, including fewer than 70 reproductively active females. Human impacts continue to threaten the survival of this species.

Today, fewer than 350 North Atlantic right whales remain. Impacts from human activities, such as entanglement from fishing gear and collisions with vessels, are the greatest dangers to these whales. Climate change is also affecting their habitat and the location and availability of their prey.

Mature North Atlantic right whales today grow around one meter shorter than they did 30 to 40 years ago. Their stunted growth means female whales produce fewer offspring during their reproductive years, limiting the recovery of this endangered species. 

Watch the video below to learn why North Atlantic right whales are smaller and what that means for the outlook of the species. 

Last updated by Office of Communications on January 31, 2024

North Atlantic Right Whale Climate