Tracking impact of sea ice loss on walruses

Research by the U.S. Geological Survey and Russian scientists is shedding new light on the ways in which the shrinking Arctic sea ice extent is impact walrus behavior. The research, published in November in the journal Marine Ecology Progress Series, has found that the early melting of ice in the Chukchi Sea is causing walrus to move to their northern feeding grounds in the Chukchi earlier in the year, while complete melting of the sea ice in the fall is driving large aggregates of walruses to “haul out” onshore.

Scientists have not yet determined the effects of these behavioral changes on the walruses, but there are concerns that young walruses are susceptible to mortality from trampling when onshore, and feeding from onshore locations may expend more energy than is used when feeding from offshore ice floes, the U.S. Geological Survey says.

The scientists conducted their research by using darts to attach radio-tracking tags to 251 walruses in the Chukchi Sea. The tags enabled the scientists to track the locations of the animals and to determine whether the animals were in the water and feeding. The result was detailed maps of walrus seasonal movements and feeding patterns relative to the distribution of sea ice.

“The loss of sea ice is the ‘why’ for the change in walrus behavior; the tracking data tells us the ‘where’ in terms of their new forage patterns,” said U.S. Geological Survey Director Marcia McNutt on Nov. 14 when announcing the publication of the research. “What awaits to be seen is ‘how much will it matter?’”

The Geological Survey says that data from the research will prove valuable for resource management in the Arctic offshore: Areas of walrus foraging overlap with outer continental shelf oil and gas leases.

—Alan Bailey