ANCHORAGE -- A shrinking polar icecap could force major changes in the seasonal habits and health of walruses and polar bears off Alaska's north coast and already may be stressing some animals by forcing them to look farther for food, scientists say.
``That's one hypothesis,'' said Alan Springer, a wildlife specialist at the University of Alaska Fairbanks. ``There's some evidence that Alaska walruses in the last two to three years were a low weight. It's not known why.''
With the ice pack retreating farther north now in summer, walrus cows and calves must haul out far from their normal feeding areas on the continental shelf, said Springer and Rosa Meehan, chief of the U.S. Fish and Wildlife Service's marine mammals division in Anchorage.
Walruses are bottom feeders, diving to the ocean floor for clams, mollusks and sea cucumbers. The shelf is rich with such foods and shallow enough to allow walruses to reach them easily.
``North of the continental shelf, the water depths are extreme,'' Springer said. When the ice pack drifts that far north, walruses ``either have to dive really deep, or they have to swim a long distance to get to shallower water.''
But too little information is available to draw any conclusions, Meehan and Springer said.
``A real limitation on trying to sort through all this is we really do not have a good population estimate,'' Meehan said. ``So the best we can do is speculate on what may happen.''
Carl Kava, director of the Alaska Eskimo Walrus Commission, said the commission wants to work with biologists on a reliable walrus census.
A population census on walrus hasn't been done in about 10 years, Kava said. That kind of work is expensive and difficult because the females and calves follow the ice and tend not to congregate, Kava and the biologists said.
Kava, from Savoonga, said elders and walrus captains in his village have noticed unusual ice conditions in recent years.
``They mention that they're not getting the usual icebergs from the north anymore'' in winter ``and most of the ice they do get is formed because of cold weather, not the big icebergs coming down,'' Kava told the Anchorage Daily News.
Bears and other game followed the icebergs.
Pack ice in the Bering Sea has been developing later in autumn over recent years.
Scott Schliebe, a polar bear project officer with the Fish and Wildlife Service, said that translates into fewer polar bears for Native hunters.