ANCHORAGE — A federal study of polar bears in the Chukchi Sea has detected no ill effects to the animals from a loss of sea ice.
The U.S Fish and Wildlife Service study of the ocean waters between northwest Alaska and Russia indicates polar bears are as healthy as they were 20 years ago, Alaska Public Radio Network reported.
“So, despite some significant sea ice loss in the Chukchi Sea region, bears have maintained their size, they’ve maintained their body condition, which means their fatness and their level of reproduction,” biologist Eric Regehr said.
That’s in contrast to studies of polar bears in the southern Beaufort Sea, where federal scientists have recorded lower body weights and reduced cub survival.
Polar bears are marine mammals and spend most of their lives on sea ice.
They’re listed as a threatened species because of sea ice loss and projected additional losses as the climate warms.
Regehr has measured, weighed and sampled more than 250 polar bears on Chukchi Sea ice since 2008. Male Chukchi Sea bears average 100 more pounds than southern Beaufort Sea bears.
“Indeed, at present time it is something of a tale of two populations,” Regehr said. “Polar bears in Western Alaska appear to be doing well, despite large sea ice declines; polar bears north of Alaska don’t appear to be doing as well.”
The Beaufort has a longer history of sea ice loss keeping bears from their preferred hunting habitats. If Chukchi bears have reduced access to seals, it’s not affecting their size, Regehr said.
“These animals live in a very productive ecosystem,” he said. “So yes, in the past 25 years, the sea ice has reduced, they have less time on sea ice, but we think they probably have enough time on the sea ice to catch as many seals as they need to survive.”
If ice continues melting at the current rate, Chukchi bears could have a different fate.
“At some point, the sea ice will have declined far enough that polar bears aren’t able to do what they do,” Regehr said. “They don’t have enough time to spend on the sea ice to catch enough seals to remain fat and healthy and have a lot of cubs.”
The research appears in the latest issue of Global Change Biology.