Polar bears in western Arctic going hungry

Posted: 11 February 2009

Polar bears in the western Arctic are struggling to find food during the critical spring period, according to a recent report.

University of Alberta and Environment Canada scientists compared current samples of the bears' waste with those from 20 years ago and determined that nearly a third more polar bears are going hungry in the spring than went hungry in the 1980s.

Canadian polar bears are going hungry
Canadian polar bears are going hungry
A recent study predicted that two-thirds of the world's polar bears - including all of those in Alaska and most of Canada's western Arctic - will be gone by 2050. Photo credit: A.E. Derocher, University of Alberta
Seth Cherry, a member of the research team from the University of Alberta, came to the conclusion after comparing blood samples taken from polar bears in 1985-86 and comparing them to samples taken two decades later when sea ice cover was near or at record lows.

By measuring the ratio of urea to creatinine - waste materials found in bears that are byproducts of metabolism - scientists can tell whether an animal is fasting.

The hunger could be correlated to rapidly disappearing sea ice, which provides habitat for seals - one of polar bears' main food sources - as well as hunting platforms for the bears to find the seals.

Sea ice in the Arctic has been thinning. Records for low ice cover were set in 2005 - and again in 2007, when the Northwest Passage was ice-free for the first time in recorded human history. In the Beaufort Sea, the spring melt of sea ice began an average of 13 days earlier between 2000 and 2005 than it did throughout the 1980s.

In itself, the study is not a firm sign that the polar bears in the Beaufort are suffering the same fate as those in western Hudson Bay, where the link between population decline, the increasingly poor physical condition of bears and melting sea ice is much more clear.

But Cherry believes there is reason to be concerned that bears in the western Arctic are heading in the same direction.

"The large-scale changes to Arctic marine ecosystems that have occurred since the beginning of this study appear to be affecting the hunting success of polar bears in the Beaufort Sea," he said. "The nutritional stress we are currently observing could be a precursor to future population declines if sea-ice conditions remain the same or worsen."

A panel of experts under contract with the US Geological Survey predicted in a survey recently published in the journal Polar Biology that two-thirds of the world's polar bears - including all of those in Alaska and most of Canada's western Arctic - will be gone by 2050. The only ones remaining, the panel warned, will be those animals inhabiting the High Arctic regions of Canada and western Greenland.