Walrus rafts not needed for now to replace sea ice off Alaska coast: U.S. agency
Wildlife group said rafts could give walrus greater access to food, reduce drowning deaths
The U.S. Fish and Wildlife Service has declined for now to create artificial floating platforms for Pacific walrus that come ashore in Alaska because they lack summer sea ice.
The agency's decision came in response to a suggestion by a wildlife advocacy group to place experimental rafts over a prime Chukchi Sea feeding area about 160 kilometres off Alaska's coast, said Geoffrey Haskett, Alaska regional director for the U.S. Fish and Wildlife Service, in a letter Monday.
"We do not think such a measure is needed at this time," Haskett said in the letter to Rick Steiner of Oasis Earth.
An estimated 35,000 Pacific walrus were photographed Sept. 2 near Point Lay in what has become an annual September phenomenon tied to shrinking sea ice attributed to climate warming.
Walrus dive to feed on clams, sea snails and other food on the ocean bottom but cannot swim indefinitely. In recent years, sea ice has receded north beyond the shallow continental shelf to water that exceeds three kilometres deep, beyond the diving range of an adult walrus.
The trend continued this year. The National Snow and Ice Data Centre said the Arctic hit its summer minimum last week with 4.4 million square kilometres of sea ice, down 620,000 square kilometres from 2014. It's the fourth lowest level on record for summer sea ice in September.
Rafts suggested to avoid long swims, drowning deaths
Walrus in large numbers were first spotted on the U.S. side of the Chukchi Sea in 2007.
When the animals are grouped shoulder to shoulder in massive herds, they are subject to stampedes if startled by an airplane, hunter or polar bear. The carcasses of more than 130 mostly young walruses were counted after a stampede in September 2009 at Alaska's Icy Cape.
In July, Oasis Earth suggested the Fish and Wildlife Service consider the resting platforms for walrus and offered to raise funds toward the cost. The group proposed a pilot project to anchor at least one barge with appropriate surface material for walrus at Hanna Shoal from July through October.
Rafts, the group said, could give walrus more time offshore to access a greater amount of food and could reduce drowning deaths among the animals.
Potential disturbance from artificial platforms
Haskett said seasonal loss of Chukchi Sea ice results in two management concerns: disturbances to walrus on shore and the amount of extra calories they may burn by making long swims to find food.
The disturbance issue, he said, has already been addressed with measures to avoid stampedes, including suggested flight restrictions.
There is no evidence at this time, he said, that feeding trips from coastal walrus "haul-outs" are resulting in major energy loss for walrus. U.S. Geological Survey scientists, Haskett said, are researching that issue and should have a study completed next year.
The potential disturbance caused by artificial platforms to walrus could outweigh the benefits, he said.
"Rafts would have to be deployed and retrieved annually and deployment would likely have to occur after thousands of animals have already occupied the area," Haskett said in his letter.
Though a small number of rafts are technically feasible, he said, the logistics, permitting and public relations challenges would be immense and expensive.
"To be effective at the population level, rafts would have to accommodate 10,000 to 20,000 animals," he said.
A walrus on a beach covers about 1.1 square metres. The service would have to provide a minimum of 11 to 22 square kilometres of rafts, he said.
"The service does not have the funds or personnel to take on more than an advisory role in such a project," he said.