No sea ice, no problem for Svalbard polar bears - for now

A study in Scientific Reports finds that polar bears of the Svalbard area, part of the Barents Sea subpopulation, have kept a steady body condition even though sea ice has shrunk over several decades. Co-author Andrew Derocher, a professor of biological sciences at the University of Alberta, said the bears are doing OK, which makes sense once the whole ecosystem is considered. The animals appear to be adjusting and still get the food they need.

The researchers used data from live captures in the Svalbard archipelago between 1995 and 2019. The group is one of 20 recognised subpopulations. Some bears stay on land when the ice is gone, while others range as far as Franz Josef Land in Russia. The work covered 770 bears, caught, marked and recaught with the help of helicopters. Jon Aars, the study's lead author and a senior scientist with Norsk Polarinstitutt (the Norwegian Polar Institute), spoke to CBC News from Longyearbyen. Height, girth and other measurements serve as a simple stand-in for a bear's fat, he said.

From 2005 onward, sea ice broke up a month earlier, and the bears faced an additional hundred days, on average, without ice. Body condition fell at first, then recovered and levelled off. Aars said it is surprising that the bears do so well with much less time on the ice.

Experts link this to other prey. John Whiteman, chief research scientist at Polar Bears International, not involved in the study, suggested unusually rich alternatives to ringed seals and bearded seals. Aars and Derocher pointed to walruses, which have recovered since being protected from hunting in 1952. Bears eat bird eggs and whale carcasses too. Such prey does not depend on sea ice.

The experts said the adjustment may be temporary and that further ice loss will still harm polar bears. Marie Auger-Méthé, a statistical ecologist at UBC, also not involved, said Canadian bears are not doing well, with western Hudson Bay data showing declines tied to ice, as in the Beaufort Sea. Derocher said the century-end fate of the Barents Sea bears is a wild card.