Scientists draw attention to low number of North Atlantic right whale births


2022–2023 calving season comes to a close with 11 mother-calf pairs

“Pilgrim” (Catalog #4340) and her calf in Cape Cod Bay on April 9, 2023. CREDIT: New England Aquarium/Woods Hole Oceanographic Institution, taken under NOAA permit #21371

BOSTON, MASS. (April 21, 2023) – As North Atlantic right whale calving season ends, New England Aquarium scientists are celebrating the births while emphasizing that the number of mother-calf pairs documented this season is far below what is needed to sustain the critically endangered species.

The annual calving season in the southeastern United States produced 11 mother-calf pairs and a twelfth calf without an observed mother. Nine of those calves were born by the end of December, with the last one detected on January 20. (A full list is available on the Aquarium’s blog.) Aerial survey teams from Florida, Georgia, and the Carolinas conducted regular flights until April 15, at which point most of the right whales had migrated north. In the last 10 years (2014–2023), scientists have documented 108 calves born, while the previous 10 years (2004–2013) yielded 216 calves.

“There were half as many right whales born this past decade. To reach the previous decade’s number, we would need an average of 22 right whales born each year. It is certainly concerning for a population that has experienced a sharp decline in recent years,” said Senior Scientist Philip Hamilton, who leads the Aquarium’s right whale research program in the Anderson Cabot Center for Ocean Life.

The current North Atlantic right whale population is estimated at less than 350 individuals, representing an ongoing downward trend for the species amid concerns that human impacts are affecting the animals’ ability to survive and reproduce. Until recently, right whales began calving by age 10, but now most are not doing so: Nearly 50 female whales over the age of 10 who were seen in recent years have not calved. “Pilgrim” (Catalog #4340) ended up being the only new mom of the 2022-2023 calving season, surprising researchers by breaking this new pattern and giving birth to her first calf at 10-years-old.

Ten of the 11 mothers have already been seen in Massachusetts waters this spring by scientists from the Center for Coastal Studies and other research groups. “Porcia” (Catalog #3293) and her calf were sighted in Cape Cod Bay on March 18, an early arrival to the area that could be indicative of shifts in the timing of right whales’ northward migration amid warming ocean temperatures. Previous research published by New England Aquarium scientists Dr. Dan Pendleton and Dr. Laura Ganley has found that highly migratory marine mammals can and do adjust the timing of their habitat use in response to climate-driven changes in their environment, with right whales using Cape Cod Bay for a longer period of time. As right whales shift their habitat use as a result of climate change and availability of food resources, the animals are at greater risk of both vessel strikes and entanglements in fishing gear along the East Coast of the U.S. and Canada.

“So far, the only mother from the calving season not spotted in Cape Cod Bay is ‘Archipelago’ (Catalog #3370), which is not a big surprise since she didn’t bring either of her previous calves to these waters. We have found that some mothers feed elsewhere, though we don’t always know where. That’s why ongoing research and monitoring is so critical to both understanding and protecting this species,” Hamilton said.

For decades, the whales’ histories have been tracked using the North Atlantic Right Whale Catalog, an extensive photo-identification database curated by scientists at the Aquarium. Individual North Atlantic right whales are distinguished by photographs of the natural markings on their head, called callosities, as well as scars on their bodies. Because calves’ callosities take months to develop, they are generally identified and tracked in the first year by their close association with their mothers in the calving grounds. A twelfth calf, a newborn whale with no observed mother which could not be identified and tracked this way, was found dead under a pier in Morehead City, North Carolina, in January.

The New England Aquarium has been studying North Atlantic right whales, one of the world’s most endangered large whale species, for more than 40 years. In addition to their work tracking the histories of each whale through the Catalog, Aquarium scientists are pioneering hormone and stress research, working with fishermen to develop innovative fishing solutions, assessing and tracking anthropogenic injuries, and conducting aerial surveys to monitor the animals’ habitat use, which provides crucial information to better protect the species.

To raise awareness about the plight of right whales, the Aquarium is marking the first annual Massachusetts Right Whale Day on April 24, a day established by law just before Gov. Charlie Baker left office. A number of events are planned at the Aquarium. More information can be found here.


Pam Bechtold Snyder –, 617-686-5068