New study shows differing polar bear response to ice melt

Dr. Eric Regehr monitors a polar bear during Chukchi Sea research in 2013. This is one of 68 bears that the U.S. Fish and Wildlife Service sedated, studied, and released as part of the ongoing project. Photo courtesy of the U.S. Fish and Wildlife Service. As Arctic ice continues to melt at historic rates, scientists are studying the ecological impacts of the changing landscape, including on the impact of shrinking sea ice on polar bear populations.  A recent story on Alaska Public Radio offered the following insights: Polar bear numbers in the Chukchi Sea appear unaffected by diminishing sea ice while polar bears in Alaska’s southern Beaufort Sea are struggling to find enough food as ice melts.

The findings come from a U.S. Fish and Wildlife Service study.

The study concludes the Chukchi Sea bears are as healthy as they were 20 years ago.

By contrast, the bears off Alaska’s north coast, in the Southern Beaufort Sea, weigh on average 100 pounds less than their Chukchi Sea counterparts, suggesting their viability is suffering as a result of the loss of sea ice, according to the media report.

“Indeed at present time it is something of a tale of two populations,” Dr. Eric Regehr, a U.S. Fish and Wildlife biologist told Alaska Public Radio. “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 news report offered the following interpretation:

In the Southern Beaufort Sea there’s a longer history of sea ice loss keeping bears away from their preferred hunting habitats, over the biologically productive waters of the continental shelf. And the Chukchi Sea is full of warm, nutrient rich water that produces a lot of food.

Regehr says bears in the Chukchi may have reduced access to seals, but if so, it’s not affecting their size.

“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.”

Regehr says the bears still face a grim long term future, but the new research shows there will be a lot of nuance along the way in how climate change plays out for polar bears in the Arctic.  —Rachel Walker