Climate change-induced shifts in the Gulf Stream are driving North Atlantic right whales to extinction by damaging the food chain and forcing the whales to migrate to more dangerous waters, according to a study published in Oceanography. Fewer than 360 of these whales are thought to be remaining.
“Anthropogenic climate change is causing species distribution shifts all over the world,” said Erin Meyer-Gutbrod, as assistant professor at the University of South Carolina and an author of the study. “The right whale’s story can serve as a lesson to start expecting the unexpected and implement more flexible management schemes.”
Meyer-Gutbrod and her team found that the weakening of the Gulf Stream due to a warming global climate has pushed its warmer waters north and west into the Gulf of Maine and off the coast of southern Nova Scotia – the traditional foraging grounds of North Atlantic right whales.
Right whales mainly eat the copepod species Calanus finmarchicus at its later developmental stages, and its abundance is closely tied to the number of newborn right whale calves. The waters off of Maine and Nova Scotia were found to be less rich with these copepods after 2010, which coincided with the shift in the Gulf Stream’s path and resulting warming waters. Meanwhile, the number of newborn calves plummeted.
As a result, fewer right whales were spotted in their traditional foraging spots, and they instead began to forage in the Gulf of St. Lawrence to the north of Nova Scotia, which did not have a management plan for this species at the time. This was followed by a spike in the number of right whale carcasses discovered, with 17 found in the summer of 2017 and 10 in 2019. Many of the whales died from being hit by ships or entangled in fishing gear.
This is a major loss for one of the world’s most endangered whales and presents the greatest threat to North Atlantic right whales since uncontrolled whaling brought them to the brink of extinction before they became protected in 1935.
There has been some discussion on ways to prevent human-caused right whale deaths. Shipping lanes can be shifted to avoid areas where the whales are spotted. Ships could also travel at a slower speed, which may reduce ship strike mortality by 90 percent. Fishing gear that uses weaker ropes – or even ropeless gear – has also been proposed to prevent entanglement.
The Canadian government has announced that it will continue its policy of closing off fishing areas in the Gulf of St. Lawrence whenever right whales are spotted, as well as restrict the speed of vessels in the gulf. The U.S. National Oceanic and Atmospheric Administration has also set out new fisheries regulations to protect the whales that includes the use of weaker rope and the addition of some new seasonal restricted areas, though the lobster industry opposes these restrictions and conservation groups consider the rules too weak.
Only time will tell whether these measures will prevent human-caused whale deaths. Nevertheless, Meyer-Gutbrod still has hope for their survival.
“I absolutely think there is room for optimism,” she said. “Right whales used to occupy a much greater range in the North Atlantic, so we know they can be successful in many different habitats. The most important thing is to reduce human-caused mortalities, and the good news is we have control over that!
“We need to work together with the shipping and fishing industries to find solutions that will work for everybody.”