Hundreds of Pacific walruses came ashore to a barrier island on Alaska's northwest coast, the earliest appearance of the animals in a phenomenon tied to climate warming and diminished Arctic Ocean sea ice.

The U.S. Fish and Wildlife Service announced Wednesday that several hundred walruses were spotted during the first week of August near the village of Point Lay on the Chukchi Sea. Last week, the number had grown to 2,000, said spokeswoman Andrea Medeiros in an email response to questions.

It's the earliest date for the arrival, known as a "haulout," to form, the agency said. Walruses from now until early fall are expected to use the barrier island and other locations along the coast as resting areas as they move to and from feeding areas.

Walrus dive hundreds of feet to eat clams on the ocean bottom, but they cannot swim indefinitely. While adult females dive, sea ice gives calves a safe resting place, with plenty of space to see the approach of predators such as polar bears.

In winter, the southern edge of sea ice is in the Bering Sea. As temperatures warm, ice recedes north all the way through the Bering Strait into the Chukchi Sea. Walruses stay on the edge, and they use the ice as a sort of conveyor belt that continually moves over new ocean bottom.

With global warming, however, sea ice in recent years has melted much farther north, beyond the shallow continental shelf, over water more than 10,000 feet (3,050 meters) deep. That's far too deep for walruses to reach the ocean bottom.

Instead of staying on sea ice over the deep water, walruses have come to shore, sometimes gathering in herds of more than 35,000.

Walruses packed shoulder to shoulder in large numbers face the threat of a stampede. If a herd is startled by a polar bear, hunter, airplane or boat, the animals rush to the safety of the ocean, often crushing smaller walruses.

Observers from Point Lay told the U.S. Fish and Wildlife Service they already have seen three to five dead animals.

"It was kind of heartbreaking to see that these animals were being wasted this way, in this manner," said Leo Ferreira III, tribal president, in an interview taped by the agency. "We're trying to protect the walruses from disturbance by aircraft, boat, and ship activity in our area."

The village and the agency actively discourage people flying to the village to photograph the walruses.

Pacific walruses are hunted for food by residents of Point Lay and other villages.