ANCHORAGE - As federal marine mammal experts in Alaska scramble to study how global warming will affect walrus, polar bears and ice seals, they warn there are limits to the protections they can provide.
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They can restrict hunters, ship traffic and offshore petroleum activity, but they acknowledge there are limits if the animals' basic habitat - sea ice - disappears every summer.
"Ultimately, it's beyond my scope," said Joel Garlich-Miller, a walrus expert for the U.S. Fish and Wildlife Service in Anchorage. "I can't make ice cubes out there."
Garlich-Miller spoke after confirming that 3,000 to 4,000 mostly young walrus died this year in stampedes on land on the Russian side of the Chukchi Sea, the body of water touching Alaska and Russia just north of the Bering Strait. Instead of spending the summer spread over sea ice, thousands of walruses were stranded on land in unprecedented numbers for up to three months.
If current ice trends continue, and walrus are based on coastlines every summer, they will put tremendous pressure on nearby foraging areas rather than rich offshore feeding area - sort of like putting all the cattle from a farm into one small pasture, said Tony Fischbach of the U.S. Geological Survey.
Experts on summer sea ice say it's not likely to suddenly reappear. Arctic sea ice this summer plummeted to the lowest levels since satellite measurements began in 1979, according to the National Snow and Ice Data Center at the University of Colorado.
"Certainly we look like we're on a death spiral right now," said Mark Serreze, senior research scientist. "Losing that summer sea ice over by 2030, within some of our lifetimes, is a reasonable expectation."
Sea ice loss could have a devastating effect. The U.S. Fish and Wildlife Service within weeks will decide whether to list polar bears as "threatened" under the federal Endangered Species Act because of the loss of sea ice from global warming. Polar bears hunt and breed on sea ice and are poor candidates for survival if they are based on land, where grizzly bears dominate.
Polar bears' primary prey are ringed seals, as many as 43 per year. They're the only seals that thrive under sea ice, digging breathing holes with their thick claws and creating lairs on top of the ice where they birth their young. With warming, those lairs collapse earlier in springtime, leaving hairless pups susceptible to freezing, foxes, polar bears and even ravens and gulls.
And then there's the Pacific walrus, in line for a triple whammy. Their ocean habitat may be changing, they may be forced to shore for long periods and their weakest members are in danger when crowded on land.
Ice disappeared this summer in the Chukchi and walruses hauled out on Alaska's northwest shore in groups of up to 2,500 animals. On the Russian side, where the trend started about a decade ago, one coastal haulout reached 40,000 animals.
If animals are on shore for three months every summer, they can't reach offshore foraging areas. Chad Jay, chief walrus researcher for the USGS, said there are concerns with how much energy walruses will expend swimming to nearshore foraging areas.
"I suspect they won't do very well as totally shore-based animals," said Vera Alexander, one of three members of the U.S. Marine Mammal Commission.