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The first official count of polar bears in the waters between the United States and Russia indicates that they are better off than some of their cousins elsewhere.
Polar bears are on the endangered species list due to shrinking sea ice due to climate change. According to a study published Wednesday in Scientific Reports, academic and federal researchers estimate that there is a robust and abundant population of nearly 3,000 animals in the Chukchi Sea off the northwestern coast of the United States. Alaska.
"This is very good news," said Eric Regehr, lead author of the project, who initiated the project more than a decade ago as a biologist with the US Fish and Wildlife Service and joined the Polar University of Washington Science Center.
In the long run, this does not mean that the Chukchi sea bear population will not be affected.
"Polar bears need ice to hunt for seals and the ice should be degraded until the underlying problem of climate change is resolved," Regehr said.
The study shows that there are variations in the world of the effects of sea ice loss on polar bears, he said Thursday.
"Some subpopulations are already declining while others are doing well," he said.
Polar bears are classified as marine mammals because they spend most of their life on sea ice. Less sea ice means less productive time to hunt seals on the ice, more time on shore and more swimming. long and more energy intensive.
The polar bears of the world are divided into 19 subpopulations, two of which are in American waters. In addition to Chukchi bears, the United States shares the population of the southern Beaufort Sea with Canada.
In 2008, the United States declared that the polar bear was an endangered species in the southern Beaufort Sea, caused by the loss of sea ice.
Fewer pups survived in their second year and adult males weighed less and had smaller skulls, found the US Geological Survey. Researcher Steven Amstrup, at the time, said the trends were consistent with changes in nutritional status, likely associated with the decline of sea ice.
Karyn Rode, a more recent study from the USGS, revealed that Chukchi bears spend more time on land and have almost 30 days less to hunt for seals on ice than 20 years ago, said Regehr. However, this does not seem to have affected the population, he said.
Polar bears have an amazing ability to build up fat reserves, said Regehr, and the abundant seal population at Chukotka apparently allows bears to compensate for the loss of hunting time. The difference with the southern Beaufort Sea was obvious by plane, he said.
"It's striking for me, the difference, to have worked in both places," Regehr said.
When the ice melts, many Chukchi bears rest on the Russian island of Wrangell, where they can sometimes find a whale or walrus carcass.
The Chukchi population study used data collected by sampling about 60 polar bears between 2008 and 2016. Some were equipped with GPS transmitters. The data were used in a model designed to estimate the population size of large highly mobile carnivores.
Blaine Griffen, associate professor of biology at Brigham Young University, said that the study was good news.
"It's nice to see that at least one population is doing better than others," he said.
The difference may be geography, he said. The Chukchi Sea has a larger continental shelf area with primary productivity that allows the food chain to support seals.
The research is consistent with earlier studies showing that Chukchi bears are doing better than those in other countries, Griffen said.
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