Tens of thousands of walruses have come ashore in northwest Alaska because the sea ice they normally rest on has melted.

U.S. government scientists say this massive move to shore by walruses is unusual in the United States.

But it has happened at least twice before, in 2007 and 2009. In those years Arctic sea ice also was at or near record low levels.

The walruses “stretch out for one mile (1.6k) or more. This is just packed shoulder-to-shoulder,” U.S. Geological Survey biologist Anthony Fischbach said in a telephone interview from Alaska. He estimated their number at tens of thousands.

The federal government is in a year-long process to determine if walruses should be put on the endangered species list.

During normal summers, the males go off to play in the Bering Sea, while the females raise their young in the Chukchi.

The females rest on sea ice and dive from it to the sea floor for clams and worms.

“When they no longer have a place to rest, they need to go some place and it's a long commute,” Fischbach said. “This is directly related to the lack of sea ice.”

Although last year was a slight improvement over previous years, Serreze says there's been a long-term decline that he blames on global warming.