Scientists have unveiled new video documentation of what they say is another stunning effect of the world's steadily warming oceans: the unusual haulout of as many as 20,000 walruses off the coast of Alaska.
The video compiled by the U.S. Geological Survey's Alaska Science Center, together with data from radio collars affixed to some of the animals, could help scientists learn more about the problems posed by shrinking sea ice for the creatures that call the Arctic home. The ice has been documented this year as among the lowest in recorded history.
Walruses normally spend summers far offshore in the Chukchi Sea, foraging for food on the relatively shallow continental shelf and resting on floating ice. But much of the ice isn't there this year. So the animals are forced either to dive unusually deep off the continental shelf looking for food or to lumber ashore and try to find food there.
This is the fourth recent year that the coast near the village of Point Lay has hosted the walrus gathering.
For an animal under consideration for the endangered species list, the behavior is problematic. Most of the animals ashore are females with calves, and calves can be trampled to death when so many animals crowd together, said Chad Jay, walrus project leader for the USGS' Alaska Science Center.
Moreover, scientists aren't sure there is enough food so near shore. Adult walruses consume more than 100 pounds of food a day, mainly clams, snails and marine worms foraged from the ocean floor. That's why they prefer not to venture into deep water off the continental shelf, now the only place left with sea ice during the summer.
"They become a little more restricted in the areas they can forage, because they now can only access what's available from shore," Jay said in an interview.
Walruses have been swimming as far as 40 miles offshore from the haulout to find food, he said.