October 08, 2007 12:00am
THOUSANDS of walruses have appeared on Alaska's northwest coast in what conservationists are calling a dramatic consequence of global warming melting the Arctic sea ice.
Alaska's walrus, especially breeding females, in summer and autumn are usually found on the Arctic ice pack.
But the lowest summer ice cap on record put sea ice far north of the outer continental shelf, the shallow, life-rich shelf of ocean bottom in the Bering and Chukchi seas.
Walrus feed on clams, snails and other bottom dwellers. Given the choice between an ice platform over water beyond their 192-metre diving range or gathering spots on shore, thousands of walruses chose Alaska's rocky beaches.
"It looks to me like animals are shifting their distribution to find prey," said Tim Ragen, the executive director of the federal Marine Mammal Commission.
"The big question is whether they will be able to find sufficient prey in areas where they are looking."
According to the National Snow and Ice Data Centre at the University of Colorado at Boulder, September sea ice was 39 per cent below the long-term average from 1979 to 2000.
Sea ice cover was in a downward spiral and might have passed the point of no return, with a possible ice-free Arctic Ocean by northern summer 2030, senior scientist Mark Serreze said.
Starting in July, several thousand walruses abandoned the ice pack.
The immediate concern of new, massive walrus groups for the US Fish and Wildlife Service is danger to the animals from stampedes.
Longer term, biologists fear walrus will suffer nutritional stress if they are concentrated on shoreline rather than spread over thousands of kilometres of sea ice.
This has been the case for some time and the alarming trend appears as if it will continue. There have been numerous science articles on this subject. A more recent text is from Science entitled: A major ecosystem shift in the North Bering Sea.