Fin whales are making a comeback in Antarctic waters, a study finds

From a distance, it looks like a dense fog on the horizon. But as the ship drew closer, the ocean bubbled as 150 fin whales, the second largest creature on the planet, dived and plunged into the water.

Six weeks after a nine-week expedition, near the coast of Elephant Island, northeast of the Antarctic Peninsula, researchers stumbled across the largest school of fin whales ever recorded.

“It’s one of the most spectacular observations I’ve ever had,” said Helena Herr, a marine mammal ecologist at the University of Hamburg. “The fin whales seem to be going crazy because of the amount of food they are facing. It’s completely thrilling. “

Dr Herr and her colleagues documented the return of large numbers of fin whales back to the waters that once made up their historic feeding grounds in an article published Thursday in the journal Scientific Reports. The study provides a glimmer of good news about a worrying backdrop for global biodiversity and ocean species in particular.

Human is Accelerating extinction at an unprecedented rate, according to the assessment of the United Nations. In the ocean, recent model has estimated that global warming due to continued greenhouse gas emissions could cause the mass death of marine species by 2300.

However, the recovery of the fin whale population is “an indication that if you implement management and conservation work, the species has a chance to recover”, Dr. Herr said.

For much of the 20th century, the scene in the seas around Antarctica was markedly different. Between 1904 and 1976, commercial whalingers descended on the rich feeding grounds and killed an estimated 725,000 fin whales in the Southern Ocean, reducing their population to just 1% of the population. size before whaling.

Finally, the parties to the International Whaling Commission Vote to ban whaling in 1982After a decades-long campaign by environmental groups to save whales, several species – including fin whales, chimpanzees and sei – have been hunted to near extinction.

But 40 years after the ban on commercial whaling, researchers studying other species in the Southern Ocean began to notice that fin whales were returning more and more.

This was the case with Dr Herr and her colleagues in 2013. At the time, they were investigating Minke whales when they came across schools of largefin whales “by chance”. They decided to apply for funding to study fin whale revival.

In 2018 and 2019, researchers returned to the Antarctic Peninsula to conduct the first dedicated study of fin whale populations. Through aerial surveys, researchers have documented 100 groups of fin whales, ranging in size from one to four individuals. They also recorded eight large groups of up to 150 whales that gathered to feed.

The survey “confirms that this pattern is still happening and is emerging even more strongly,” said Jarrod Santora, a fisheries biologist with the National Oceanic and Atmospheric Administration who is a member of the National Oceanic and Atmospheric Administration. one of the first researchers to document an increasing number of fin whales while studying krill. (He was not involved in this new study.)

Whale researchers warn that not all whale species have successfully recovered since the ban on whaling. Sally Mizroch, an aquatic biologist who has studied whales since 1979 and was not involved in the study, describes fin whales as “very successful”. Unlike other species, such as blue whales, fin whales can forage over great distances and feed on a variety of food sources.

Scientists aren’t sure why some gatherings are so large. Dr Herr notes that the scenes they witnessed bear at least some resemblance to historical reports written before commercial whaling was common. For example, the naturalist William Speirs Bruce described seeing whale backs and extended explosions “from horizon to horizon” during an Antarctic expedition in 1892.

Recent research has suggested that the recovery of whale populations is not only good for whales, but for the entire ecosystem, through a concept known as the “whale pump”. Scientists think that when whales eat krill, they excrete the iron trapped in the crustaceans back into the water. That could spur phytoplankton, microscopic organisms that use carbon dioxide during photosynthesis and serve as the basis of marine food chains.

Dr Santora said: “When fin whales bring krill to the surface, they can also facilitate the success of other predators, including seabirds and seals. “There is more cooperation and symbiosis than we normally grant to the ecosystem.”

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