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September 13, 2021

Cornell Researchers Investigate the Plummet of Critically Endangered North Atlantic Right Whales

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The North Atlantic right whale population — with fewer than 400 individuals — is at risk of further decline as rising sea levels force them northward toward fishing grounds where they run the risk of potentially deadly ship strikes and entanglement. 

To monitor this phenomenon, Cornell researchers are studying the soundscapes of right whales as a method of tracking and assessing changes in their migration patterns. 

With hopes to better conserve the environment by conveying results to the public and policy makers, the group recently discovered a major cause of the declining whale population — rising sea levels are forcing whales into harm’s way, near the fishing grounds of eastern Canada. 

Over the course of a decade, the Gulf of Maine has warmed faster than 99 percent of the global ocean. The increased temperatures are influenced by a northward shift in the path of the Gulf Stream, a warm current from the Gulf of Mexico to the Atlantic Ocean — which is likely caused by anthropogenic climate change. 

According to Prof. Erin Meyer-Gutbrod, Ph.D. ’16, ocean and environment, the University of South Carolina — the lead author of a recent study published in Oceanography investigating the phenomenon — increasing temperatures in the Gulf of Maine are influencing this shift in the Gulf Stream, driving a drastic change in how and where humans interact with the ocean. 

The new regime, Meyer-Gutbrod said, is less favorable for zooplankton — small aquatic microorganisms — which right whales consume, forcing the whales to abandon their traditional summertime feeding grounds in the Gulf of Maine and follow their food north to the Gulf of Saint Lawrence in Canada around 2010. 

Due to the unexpected migration, fishing policies and vessel speed restrictions that had protected the right whales in their previous habitat were not in place in their new one. This is connected to an “unusual mortality event” where 17 right whales died in 2017. Since then, the total has risen to 34 confirmed right whale deaths — almost 10 percent of the dwindling right whale population. 

“Because the population is already so small, the right whale population is super genetically vulnerable which further compounds [the decline],” said Marissa Garcia grad, a first-year Ph.D. student working at the K. Lisa Yang Center for Conservation Bioacoustics. Because there are fewer whales, and less genetic diversity, the population may be more vulnerable to disease and other threats.

One pathway to safeguard right whales as they forage into habitats in search of food is to expand protective policies, like limiting the use of certain fishing equipment dangerous for the whales, such as vertical lines. 

On Aug. 31, the National Oceanic and Atmospheric Administration announced a new fishery regulation that will go into effect May 1, 2022, including modifications to fishing gear that would reduce entanglements, and increase the likelihood that a whale may free itself from a trap by breaking through weaker ropes.

Still, researchers believe that entirely eliminating ropes in fishing is the key to mitigating whales’ entanglement. Ropeless fishing works by using acoustic communication to allow fishermen to retrieve their trap by playing a sound, signaling their gear to float to the surface, according to Aaron Rice, principal ecologist at the K. Lisa Yang Center for Conservation Bioacoustics

Most importantly, according to Meyer-Gutbrod, researchers must be able to predict where right whales will travel next and prepare for the whales’ arrival by setting up protective regulations beforehand. 

Old whaling records, zooplankton data and knowledge of the shape and depth of the seafloor allow researchers to predict what areas may attract right whales, Meyer-Gutbrod explained. 

The best way to improve these predictions is through increased monitoring — a difficult feat to accomplish across the incredibly vast ocean, Meyer-Gutbrod said. Right whales can be spotted through boat and airplane surveillance, although these methods are contingent on good weather sightings being close to the shore. 

Another tool, Garcia added, is through a method called passive acoustic monitoring. 

“Basically we drop off underwater microphones or hydrophones in the water to listen for right whale calls and they just stay there, for a very long time,” Garcia said. “The idea is that it’s passively recording the environment the whole entire time.”

Passive acoustic monitoring also provides a more durable and convenient way to observe whales since it can survey during bad weather and far from shore, Meyer-Gutbrod explained. 

According to Rice, the right whales are not the only ones that are affected by rising ocean temperatures. 

The southern Sei whales, which are the third largest whales in the western north Atlantic, typically go north and then swim down to the New York Bight, an offshore area that extends from Cape May to Montauk Point on the eastern tip of Long Island. As ocean temperatures continue to rise, a northward shift of the southern Sei whale population can be expected as well. 

As waters become warmer, tracking migration pattern changes like these will become increasingly vital. Meyer-Gutbrod called on students to support the effort by making small changes, like voting for progressive climate policies — such as New York’s newly signed legislation to aim for all new passenger cars and trucks to be zero-emissions by 2035.

“Vote. Voting for politicians that want to support broad-scale climate mitigation strategies and support science [that] can make a big impact,” Meyer-Gutbrod said.