TORONTO —
Canada’s polar bear population in western Hudson Bay has declined 27% in just five years, according to a government report released this week, suggesting climate change is affecting the animals.
Each fall, the bears that live on the western edge of the bay pass through the subarctic tourist town of Churchill, Manitoba as they return to the sea ice. This has made the population not only the best-studied group in the world, but also the most famous, with the local bear-watching economy being worth $5.30 million a year.
However, the Nunavut government’s assessment shows that only 618 bears remain in 2021 — a drop of about 50% from the 1980s.
“In a way, it’s totally shocking,” said John Whiteman, senior research scientist at nonprofit conservation organization Polar Bears International. “What’s really sobering is that this type of decline is the kind that, if sea ice loss is not halted, is predicted to eventually lead to … extinctions.”
Polar bears depend on the sea ice to hunt and lie in wait for seals’ breathing holes. But the Arctic is now warming about four times faster than the rest of the world. Around Hudson Bay, seasonal sea ice is melting earlier in spring and forming later in fall, forcing bears to go longer without food.
Scientists warned that a direct link between population decline and sea ice loss in Hudson Bay is not yet clear, as four of the past five years have seen moderately good ice conditions. Instead, they said, climate-related changes in the local seal population could drive bear numbers down.
And while it’s possible that some bears have relocated, “the number of adult male bears has stayed more or less the same. What’s causing the decline is a lower number of young bears and adult females,” said Stephen Atkinson, an independent wildlife biologist who led the study on behalf of the government.
This shift in demographics doesn’t square with the idea of bears migrating from western Hudson Bay, he added.
“Very small numbers of cubs were produced in 2021,” said Andrew Derocher, who directs the Polar Bear Science Lab at the University of Alberta. “We’re looking at a slowly aging population, and when you’re going bad [ice] Years old, older bears are much more prone to increased mortality.”
Also of concern to scientists is the report, which suggests the decline has accelerated. Between 2011 and 2016, the population fell by just 11%.
There are 19 polar bear populations distributed across Russia, Alaska, Norway, Greenland and Canada. But western Hudson Bay is among the southernmost locations, and scientists think the bears here may be among the first to go.
A 2021 study in the journal Nature Climate Change found that most of the world’s polar bear populations are on track to collapse by 2100 unless greenhouse gas emissions are severely curtailed.