Why there was a sudden collapse in the rare whale population


Climate change is the silent force behind a sudden decline in the North Atlantic right whale population, according to a new study that strengthens a growing body of research on why critically endangered animals have gone from ‘slow recovery to alarming decline.

An analysis of data on plankton, ocean conditions and whale sightings, published Wednesday in the journal Oceanography, showed that whales abandoned their traditional feeding grounds in the Gulf of Maine in 2010, the same year as the warming of the water has caused the loss of fatty crustaceans that they eat. tumble down in the area.

Many whales eventually followed their food north to the Gulf of St. Lawrence, but the protections against fishing gear and vessels that had protected them in their old habitat did not exist in their new habitat. Entanglement in gear is the leading killer of North Atlantic right whales, followed by collisions with ships.

“They went so fast that our policies did not change with them,” said Erin Meyer-Gutbrod, quantitative marine ecologist at the University of South Carolina and one of the study’s authors. “The environment just isn’t as predictable as it used to be, so I think we all need to think more. “

To make matters worse, researchers found that the decline in crustaceans resulted in lower reproduction rates. “We are slowing their births and we are increasing their deaths,” said Dr Meyer-Gutbrod. “You don’t have to be a super mathematician to guess what this change will bring about.”

Scientists have only counted 356 remaining individuals.

The research helps explain why deaths increased in 2017, prompting marine mammal officials to report an “unusual mortality event” that is still in effect. Whales tend to get tangled in ropes used for crab and lobster fishing. Ropes can drown them, sever parts of their bodies, or lead to slow death from impaired eating or swimming.

Canadian authorities responded by adding protections in the Gulf of St. Lawrence, including speed restrictions for vessels and temporary closures of certain fisheries when a whale is detected. On Tuesday, NOAA Fisheries announced new rules in US waters for catching lobster and Jonah crab that aim to reduce the number of lines from tag buoys to traps. They also weaken the lines so that tangled whales can break free.

Environmentalists have reacted with disappointment to the long-awaited rules, criticizing them for not meeting the needs of whales.

The most effective solution, according to the study’s authors, would be a transition to cordless fishing gear. “It would have a huge impact,” said Charles Greene, senior researcher at Ocean Visions, a research and advocacy group, and one of the study’s authors.

Fishermen fear that such gear is too expensive and less efficient. The key, according to activists and researchers, is to make the equipment attractive to them.

“We have to figure out how we can fund it properly so that they can effect this technological change,” said Dr Greene, former professor in the Department of Earth and Atmospheric Sciences at Cornell University. “This is what prompted people to install solar panels on the roofs of their homes. “

Various speed restrictions exist in U.S. waters to protect whales from collisions, but operators often ignore the rules, according to research from nonprofit Oceana.

Perhaps 10,000 right whales swam in the North Atlantic before the advent of large-scale whaling. They were considered good hunting targets because they moved slowly, stuck close to shore and floated when dead, while producing oil and baleen in abundance, according to the International Whaling Commission. By the 1890s, the species was hunted to the brink of extinction. But whale numbers slowly recovered after the commercial whaling ban, hitting around 500 before the current decline set in.

Previous research suggested that the loss of plankton and warming water caused the whales to move, but this study presents the strongest case to date that human-induced climate change has caused this reduction in prey, drives whales to new areas and leads to lower reproduction rates. .

“While this is upsetting due to the ultimate danger whales face, it’s no surprise that they appear to be moving north in response to these changes,” said Jaime Palter, professor of oceanography at the ‘University of Rhode Island who was not involved in the study.

Distinctive calluses on the heads of the whales allowed researchers to document each individual.

Although their natural lifespan is around 70 years, the dead, when found, are inevitably much younger. The latest victim was an 11-year-old man known as Cottontail, who was found dead off the coast of South Carolina in February. Researchers had been following him since October, when he was seen with his head and mouth tangled in a line that trailed behind him three or four body lengths.

There is hope for whales, say scientists. Nineteen calves were born this year, more than any year since 2013. Dr Meyer-Gutbrod said she believes their mothers have found more food.


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