The absence of vast swaths of summer sea ice is changing the behavior of Pacific walrus, federal scientists said Wednesday, but added that more research will be needed to predict how climate change will effect the current strong population.

“There is a definite concern for the population,” said Chad Jay, a U.S. Geological Survey research ecologist in Anchorage who studies patterns of walrus distribution.

Since 2008, Jay, USGS researcher Anthony Fischbach and colleagues in Russia have used crossbows to dart barbed radio transmitters in walruses so their movements can be tracked. The transmitters stay embedded in walrus hide for up to 12 weeks before falling off.

In a paper published last month, the scientists concluded that walruses in late summer will increase their use of coastal resting areas, called haul-outs, and feed in nearshore foraging areas because sea ice will continue to diminish. The consequences for the population, they said, was not known, but will likely add stress to mothers and calves.

A decade ago, the future of walruses was hardly a consideration. Their habitat in a hostile locale off a remote state provided natural protections.

Warming has opened up the Arctic for ecotourism, petroleum development and possibly cargo transport and commercial fishing. Like polar bears, walruses have seen their primary habitat melting beneath their feet or flippers.

Walruses cannot swim indefinitely. They use ice, rocks or beaches as resting platforms.
Walrus females give birth in the Bering Sea, and as temperatures warm each summer, live on the sea ice edge as it moves north through the Bering Strait and into the Chukchi Sea.

The ice provides a sanctuary for nursing walrus calves and an ever-changing diving platform for females that hunt along the rich sea floor for clams, snails and marine worms. Biologists compare the ice edge to a conveyor belt that carries walrus north and south as ice melts and re-forms with the seasons.

A wakeup call for U.S. scientists came in 2007, when several thousand walruses appeared on Alaska’s northwest coast in late summer. Ice had receded beyond the shallow continental shelf of the Chukchi to the Arctic Basin, where the ocean floor is 10,000 feet down and far too deep for walrus. Thousands more hauled out on the Russian side.

Remnant ice kept walrus offshore in 2008, but they returned to shore in late summer 2009, with tragic consequences: more than 130 mostly young walruses were crushed at Icy Cape in a stampede that could have been caused by a polar bear, human hunters or an airplane.

In 2010, upward of 20,000 walruses were counted near Point Lay, an Eskimo village 300 miles southwest of Barrow. In 2011, 5.000 walruses were spotted north of Point Lay and 3,000 more a short distance away.

The U.S. Fish and Wildlife Service last year added walrus to the “warranted but precluded” list, deciding that the animals need additional protections but could not be listed as threatened because other species, mainly in the Lower 48, were a higher priority for the agency’s limited resources. The administrative process for listing a species, with public hearings and rule-writing, can be arduous, but a legal settlement requires a decision on the Pacific walrus by 2017.

Researchers, meanwhile, will continue investigating whether walruses gathered on the coast will deplete nearshore food resources, which are typically less bountiful than offshore areas, or if a toll will be taken on the health of females and calves that have to “commute” farther for food. One goal of the research will be to learn whether walruses can successfully adapt on their own to changing conditions, or whether they need the protection of the Endangered Species Act to survive.

Despite record low ice this year, remnant ice floating off Alaska’s northwest allowed walruses to stay offshore. As the climate continues to warm, Jay said, walruses are likely to be back on shore in late summer.

“We expect to see this behavior continue and that period of time when walrus are using coastal haul-outs and are forced to forage in these less-productive waters — we expect that period to continue into the future as we experience more climate warming,” he said.
The USGS says the Pacific walrus population numbers about 200,000 to 300,000, and about 95 percent of them call Alaska waters their home.