SCIENCE:

Melting ice turns 10,000 walruses into landlubbers

For the third time in four years, a dearth of sea ice has forced walruses ashore in Alaska.

The lumbering marine mammals normally spend their summers resting on the ice as it floats north, making periodic dives to the ocean floor to forage for food. But this year, as in 2007 and 2009, a lack of ice in the eastern Chukchi Sea has driven thousands of walruses to congregate on land instead.

Officials with the U.S. Geological Survey and the Fish and Wildlife Service estimate that at least 10,000 animals have gathered in a dense clump at Point Lay, Alaska.

"Our biggest concern right now is stampeding," said Bruce Woods, a spokesman for the Fish and Wildlife Service's Alaska regional office. "That's the big risk posed to these animals."

That's because the intensely social -- but easily spooked -- animals have congregated in numbers that dwarf their normal groupings of up to 500 animals.

The risk of injury and death is greatest for the youngest animals, which are dwarfed by adult female walruses that weigh about 1 ton each.

Last year, when walruses sought shelter on the shore of Icy Cape, Alaska, many of the 131 animals that were trampled to death there were juveniles, USGS found. Similarly deadly stampedes have also been reported in Russia in recent years (ClimateWire, Aug. 10).

Concerns about a stampede

So far this year, there is no evidence of any stampedes at Point Lay, and federal officials are trying to keep it that way. FWS is counseling aircraft traveling through the area to maintain a minimum altitude of 1,500 feet and a lateral distance of a half-mile away from the animals. The agency is also asking ships to maintain a half-mile "buffer zone" from the coast.

News of the unusual walrus behavior comes as FWS considers extending Endangered Species Act protection to the animals. The agency has until January to decide whether affording walruses some degree of protection is warranted.

Chad Jay, a USGS research ecologist whose work includes tagging and tracking walruses, said it appears the animals started to come ashore late last month.

"They were using an area called Hannah Shoals offshore for a number of weeks, but that little bit of ice disappeared, as well," he said. "We had several animals move west and into Russian waters and find some ice over there, but quite a few animals have come to shore in Alaska."

USGS researchers had suspected the animals might shelter on shore again this year, since Arctic sea ice has hovered near the historic summer low set in 2007.

Jay said scientists had camped at Icy Cape, where walruses came shore in 2007 and 2009, waiting to observe and tag animals. But the walruses surprised them by sheltering at Point Lay, about 50 miles south.

Bleak future for ice-loving tuskers

"This is the third time in the last four years that this has happened, and we're still learning and looking for patterns," Jay said. "Anything could have happened. In 2008, there was enough ice that stayed over the [continental] shelf that they never did come ashore, but we were kind of betting the odds they would come to shore again this year."

Scientists aren't sure how long the walruses will remain at Point Lay. But what is even less clear to them is how the walruses will fare over the long term, with many models projecting the Arctic could see ice-free summers by 2040.

At USGS, Jay and his colleagues are increasing the number of walruses they track with radio collars. They've also begun studies to determine whether near-shore areas can provide sufficient food and habitat if the gregarious animals come ashore year after year.

One of their initial studies, published last week, found "a clear trend of worsening conditions" for the animals through the end of this century. The USGS scientists say that 22 percent of the Arctic's walruses could be classified as "vulnerable, rare or extirpated" by 2050, a fraction that rises to 40 percent by 2095.

"There's quite a bit of uncertainty in all of this, and the model is constructed in a way that attempted to capture as much of that uncertainty as we could," Jay said.