News

The population of polar bears along the western coast of Hudson Bay plunged by 22 per cent from 1987 to 2004, and if the trend continues, the big mammals will likely become extinct in the area within a few decades, says Ian Stirling, an Environment Canada research scientist.

During the 17-year period, bear numbers dropped to fewer than 950 from 1,200, and climate change that is literally putting the animals on thin ice is being blamed.

Global warming is causing an earlier summer melt of the ice on which polar bears hunt for ringed seals, their preferred prey, making it difficult for the bears to lay on enough fat to survive in their harsh environment.

“If the forecasts are correct and if the climate continues to warm as it has for the last 30, 40, 50 years, then I don't think there are going to be any polar bears in Hudson Bay in 25 to 40 years,” he said.

Mr. Stirling, one of the world's foremost experts on polar bears, presented the population finding last week at a U.S. conference on marine mammals.

He and three other U.S. and Canadian researchers have prepared a scientific paper on the decline that is expected to be published next year.

The bears around Hudson Bay are the world's southernmost population of these large carnivorous mammals, and if global warming is having an adverse effect, scientists believe it would likely show up first in this region.

The reduced food supply has led to something akin to a famine, cutting the survival chances of cubs, young bears between three and four years old, and the old, according to Mr. Stirling.

Adult bears are not being affected and appear to be able to cope with the adversity, which is similar to what happens to humans during periods of widespread starvation, when most adults survive but children and the old die in greater numbers.

“This is quite normal in mammal populations, that if times get tough, it's the young and the old that suffer most,” Mr. Stirling said.

The population count covered the coast of Hudson Bay from Rankin Inlet in the north to the Ontario-Manitoba boundary in the south. It includes the famed population around Churchill, Man., an international tourist attraction that has caused the community to be dubbed the world's polar bear capital.

Ontario has a separate bear population along Hudson Bay and James Bay that had an estimated 1,000 members in the mid-1980s. It is not yet known whether this group is declining, but the bears are also suffering from malnourishment.

Martyn Obbard, a research scientist with the Ministry of Natural Resources, says sampling over the past three years has found that the bears weigh an average of 15 per cent less than ones caught in the region during the mid-1980s. There has been “a significant decline in body condition in the last 20 years,” he said.

The ministry is investigating several theories for the weight loss, including a drop in seal numbers and poor ice conditions. The province is working on a new population estimate, and Mr. Obbard hopes it will be completed by early in the spring.

The bears of Hudson Bay move onto the ice when it forms each year in late November, and remain there hunting until it melts in the summer.

After breakup, the bears return to land and live off stored fat for a minimum of four months while awaiting the return of winter.

Sea ice on Hudson Bay is breaking up about three weeks earlier than it did about 30 years ago, Mr. Stirling said.

This earlier melting is a disaster for the bears because it is occurring at the time they traditionally put on large amounts of fat from the hunting of newly weaned ringed seal pups.

The seals are easy to hunt at this point because they are not yet totally wary of predators, allowing the bears to gain weight rapidly in preparation for their four-month fast.

The population decline is a major development, and suggests that a recent decision by Nunavut to approve a larger hunting program for polar bears might be ill-advised.

Earlier this year, it expanded the hunt to 55 animals from 47.

Manitoba doesn't allow hunting of polar bears because they are too valuable for the tourist industry.

Mr. Stirling says many northerners think more bears are around than before because more of them are being seen close to hunting lodges and communities.

But he says the bears are so hungry they're being forced to scavenge for food around humans. That's why there are more sightings, even though the population is falling.

Wildlife researchers have records on polar bear numbers in western Hudson Bay going back to the late 1970s. Mr. Stirling says this lengthy record makes scientists confident the population is undergoing a long-term decline, not just a short-term cyclical blip.