An estimated 25,000 Pacific walruses have gathered on the shore of northwest Alaska as the Chukchi Sea approaches its seasonal ice minimum.
Aerial marine mammal surveyors spotted the walruses on a barrier island near Point Lay on August 30 and residents in a nearby village have reported hearing the walruses.
"The herd is three to five kilometres north of the old village site on the island," US Fish and Wildlife Service Andrea Medeiros said on Thursday.
"We are monitoring the herd with the help of local people and US Geological Survey staff who are on site doing research."
Over the last decade walruses have come to shore on the Alaska and Russia sides of the Chukchi Sea as sea ice diminishes due to global warming.
Walruses use sea ice to rest as they dive to the ocean floor to hunt for clams and snails. When ice recedes north of the shallow continental shelf, walruses head to beaches to rest.
The animals lie shoulder to shoulder and can be startled by a polar bear, plane or hunter. Young animals, especially calves born earlier in the year, are vulnerable to being crushed in stampedes if the herd suddenly seeks refuge in the ocean.
Sea ice typically melts to its summer minimum sometime in September. The date varies widely, said Agnieszka Gautier of the National Snow and Ice Data Center at the University of Colorado.
"NSIDC does not have a precise date at this point," Gautier said by email. "The minimum has gone as late as Sept. 21, in previous years."
