Right whale deaths may be a casualty of climate crisis

In and around the Gulf of St. Lawrence, where five Canadian provinces converge, a string of North American right whale deaths occurred throughout this summer. For scientists like Cornell’s Charles Greene and Erin Meyer-Gutbrod, Ph.D. ’16, who study these animals, the whales may represent another casualty of the ongoing climate crisis impacting the world’s oceans.

Ten of the 13 carcasses found this summer were located in the Gulf of St. Lawrence, far north of the regions where right whales typically reside. The 13 dead whales represent more than 2 percent of the world’s remaining population of this endangered species.

Although scientists have known right whales to venture into the gulf on occasion, occupation of these more-northern waters seems to have escalated over the past several years. 

“To protect this highly endangered species from extinction, it is critical that scientists, conservationists and marine policy managers join together to understand and address these deaths immediately,” said Greene, professor of oceanography and fellow in Cornell’s Atkinson Center for a Sustainable Future.

Greene’s laboratory has been researching right whale food availability around the Gulf of Maine for nearly two decades, examining how natural climate variability over time affects calf birth rates. In 2014, the group found a pleasant scientific surprise: The North Atlantic right whale population had increased the prior decade due to an increased abundance of food.

A favorite food for right whales is the copepod Calanus finmarchicus, which prefers cold water. Its population is thought to be shifting northward to avoid the warming waters in the Gulf of Maine and the Scotian Shelf.

“In response, right whales will either have to work harder to find food or follow their food north,” said Meyer-Gutbrod, a former graduate student in Greene’s laboratory, now a postdoctoral scholar at the University of California, Santa Barbara. “We believe that may have motivated these animals to head north to the Gulf of St. Lawrence this summer. They are following the food.”

North Atlantic right whales typically swim in urbanized waters along the Eastern seaboard and in the Gulf of Maine and Bay of Fundy. Sadly, Greene said, their habitat is inundated with commercial vessel traffic and dense fishing gear. As a result, right whales are often killed by vessel strikes or entanglement in fishing gear.

Major efforts have been implemented in the Gulf of Maine to alert and slow vessels in the presence of right whales and to design whale-friendly fishing gear. “But as the right whales explore waters outside of their typical range, they are traveling and feeding in areas where these protective policies have not been implemented,” said Meyer-Gutbrod. “The unusual series of deaths in the Gulf of St. Lawrence may be driven by the shift out of these protected waters.”

The scientists said that, in response to this tragic series of right whale deaths, Canada closed the snow crab fishery last month to reduce the amount of fishing gear in the water. Greene said more can be done to safeguard this region for the endangered whales.

“Scientists need to keep working to explain how the environment, especially food availability, affects right whale behavior and population growth rates,” he said. “If we can’t figure out which population changes are caused by food, ships or fishing gear, we won’t know whether management efforts are having any effect. This type of problem will be encountered more commonly as we try to conserve endangered populations in a rapidly changing ocean.”

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Joe Schwartz