The U.S. Fish and Wildlife Service is investigating the deaths of walruses found in northwest Alaska.

Local monitors from the village of Point Lay are expected to go to the site to collect more information about the dead walruses, MacCracken said.

The U.S. Attorney in Alaska is overseeing the investigation of 25 walruses found dead and reported shot at Cape Lisburne about 100 miles southwest of Point Lay.

The missing heads and tusks don’t necessarily indicate illegal activity, Medeiros noted. They are part of the diets of Alaskan natives who live along the coast, and their tusks, bones and hides are sometimes used as part of their handicrafts.

Some walrus were missing heads and tusks.

While the FWS and the Alaska District Attorney’s office refused to comment on the incident citing the ongoing investigation, experts working on marine mammals and their habitats said the deaths could be due to a varied number of reasons.

U.S. Fish and Wildlife officers were alerted to the mass slaughter after receiving an email, with photos, stating the animals had been killed. Walrus skulls with tusk attached are collectors’ items.

However, walrus killed only for the collection of ivory is considered wasteful, and “head-hunting” is illegal.

“Maybe a hundred or a thousand of these animals had hauled out; and when these animals feel disturbed, they can trample each other in the process of hurriedly moving into the water…it is entirely possible that 25 of them are trampled in a group of a hundred or a thousand”, Horstmann-Dehn said.

The animals eat clams, sea snails and other food on the ocean bottom but can not swim indefinitely.

Walrus in large numbers on shore were first spotted on the USA side of the Chukchi Sea in 2007.

The animals were discovered near Point Lay at the same location where 35,000 walrus were spotted on shore September 2. Many walrus found in the Chukchi Sea north of the Bering Strait are females with pups that use ice as a platform from which to dive and rest. The National Snow and Ice Data Center said the Arctic hit its summer minimum last week with 1.7 million square miles of sea ice, down 240,000 square miles from 2014.

Walrus have become a cause for concern as climate warming diminishes summer sea ice.

In a press release on Thursday, the agency said that an employee of the US Geological Survey gave an image of the walrus carcasses.

Walruses united in massive herds can stampede if a polar bear, hunter or airplane approaches them.