According to a new government survey of the land carnivore, polar bears continue to die in large numbers in Canada's Western Hudson Bay, on the southern edge of the Arctic. Females and bear cubs are particularly vulnerable.

Researchers surveyed Western Hudson Bay, home to Churchill, dubbed "the Polar Bear Capital of the World,"  by air in 2021 and estimated there were 618 bears, down from 842 in 2016.

"The actual decline is much larger than I would have expected," said Andrew Derocher, a University of Alberta biology professor who has studied Hudson Bay polar bears for nearly four decades. Derocher was not a participant in the study.

The authors discovered that the number of bears in the region has decreased by nearly 50% since the 1980s. The ice that is critical to their survival is melting.

Polar bears rely on arctic sea ice, which shrinks in the summer due to warmer temperatures and reforms in the long winter. They hunt by perching near holes in the thick ice to spot seals, their favourite food, coming up for air. However, because of climate change, the Arctic has warmed twice as fast as the rest of the world, causing sea ice to crack earlier in the year and take longer to freeze in the fall.

As a result, many polar bears across the Arctic have less ice on which to live, hunt, and reproduce.

Polar bears are not only important Arctic predators. For many years, before climate change began to affect people all over the world, they were also the most visible face of climate change.

According to researchers, the concentration of deaths in young bears and females in Western Hudson Bay is concerning.

"Those are the types of bears we've always predicted would be affected by environmental changes," said lead author Stephen Atkinson, who has studied polar bears for more than 30 years.

Young bears require energy to grow and cannot survive for long periods of time without food, while female bears struggle because they expend so much energy nursing and rearing offspring.

"It certainly raises concerns about the company's long-term viability," Derocher said. "That is the population's reproductive engine."

The ability of polar bears in Western Hudson Bay to reproduce will decline, according to Atkinson, "because there are simply fewer young bears that survive and become adults."