EDMONTON — Polar bears in the western Arctic are finding it increasingly difficult to find food during the critical spring period, a recent study suggests. Seth Cherry, a PhD candidate working with University of Alberta scientist Andrew Derocher, 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.
EDMONTON — Polar bears in the western Arctic are finding it increasingly difficult to find food during the critical spring period, a recent study suggests.
Seth Cherry, a PhD candidate working with University of Alberta scientist Andrew Derocher, 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.
Mature males will often fast in the spring when they are spending almost all their energy searching for females. So it was not surprising to find that some of these animals were not eating for considerable periods of time.
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The blood samples, however, showed a sharp increase 20 years later in the number of bears that were fasting.
What's more, they were doing it for longer periods of time. It didn't matter how old the bear was or whether it was male or female — nearly a third of the bears sampled were going without food longer than they normally would.
The study was done by University of Alberta and Environment Canada scientists.
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 meltdown in the Arctic began an average 13 days earlier between 2000 and 2005 than it did throughout the 1980s.
Canadian Wildlife Service scientist Ian Stirling was the one who collected the blood samples back in 1985-86. He and other scientists have suggested that this early thaw and rapid meltdown in the Arctic will make polar bears, narwhal and hooded seals particularly vulnerable because their life cycles are so closely tied to the ice. Without ice as a platform to hunt seals, polar bears are deprived of ringed seals, the mainstay of their diet.
Ringed seals could also be vulnerable because they need stable ice cover to nurse their pups in spring.
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