Thousands of walrus are congregating on Alaska's northwest coast because of receding sea ice in the Arctic

In this undated photo provided by the U.S. Fish and Wildlife Service, walrus swim to shore on a beach in Alaska. Thousands of walrus are congregating on Alaska's northwest coast because of receding sea ice in the Arctic. An environmental group is seeking to list walrus as an endangered or threatened because of disappearing summer sea ice

This Sept. 6, 2009 photo provided by the National Oceanic and Atmospheric Administration shows walruses hauled out on the shore of Icy Cape about 140 southwest of Barrow, Alaska. Up to 200 dead walruses were spotted on another part of the cape in Northwest Alaska on the Chukchi Sea, by Federal wildlife researchers from the U.S. Geological Survey who were on their way to a walrus tagging project. The age of the dead animals nor the cause of death is known, said Bruce Woods, spokesman for the U.S. Fish and Wildlife Service.

This Aug. 23, 2009, North Slope Borough photo provided by the U.S. Fish and Wildlife Service shows veterinarians and biologists from the Fish and Wildlife Service, the U.S. Geological Survey, the Alaska SeaLife Center and the North Slope Borough taking samples from dead walruses on the beach near Icy Cape on the Chukchi Sea about 140 southwest of Barrow, Alaska. The dead walruses were spotted from the air by USGS researchers on their way to walrus satellite radio tagging projects and were likely trampled by other walruses