A remote barrier island off Alaska's northwest coast has been mobbed by thousands of Pacific walruses in recent weeks in the earliest known "haul out" for the species.

Their arrival is tied to shrinking Arctic sea ice and follows one of the hottest months on record. It also comes as Arctic sea ice extent is near a record low for this time of year.

Last month, global temperatures tied July 2016 for the warmest July in 137 years of modern record-keeping, according to a monthly analysis of global temperatures by scientists at NASA's Goddard Institute for Space Studies. July numbers released today by NOAA, the National Oceanic and Atmospheric Administration, show a sliver of difference between the two years.

Arctic sea ice extent for July 2017 averaged 3.17 million square miles, marking the fifth lowest July in satellite records going back to 1979, according to the National Snow and Ice Data Center in Boulder, Colorado. Last month's ice coverage was 610,000 square miles below the long-term average from 1981 to 2010.

Walruses rely on the ice as they hunt for food. They typically dive from floating blocks of ice to feed on clams on the ocean floor. As the ice floes melt, however, this vanishing habitat recedes farther north, beyond the shallow waters of the continental shelf and into Arctic waters too deep for the foraging animals. Then they haul up on shore, crowding together, sometimes in herds of thousands, where deadly stampedes can occur.

As of last week, approximately 2,000 of the marine mammals were on shore, U.S. Fish and Wildlife spokesperson Andrea Medeiros wrote in an email. Observers from the nearby Native village of Point Lay say they have already seen dead animals this year.

"This early haul out shows that Pacific walruses are in terrible trouble," Emily Jeffers, an attorney with the Center for Biological Diversity said in a written statement. "The walrus, within the foreseeable future, will be at risk of extinction due to the loss of sea ice."

The environmental advocacy organization has petitioned the federal Fish and Wildlife Service to protect Pacific walruses under the Endangered Species Act. A decision is expected by the end of September.

Mass walrus haul-outs were first observed off Point Lay in 2007, when Arctic sea-ice extent dropped 1 million square miles below average — an area the size of Alaska and Texas combined.

President Donald Trump's efforts to withdraw from the Paris climate accord and to open the Arctic to offshore drilling would exacerbate sea ice loss and other threats to Pacific walruses, Jeffers said.

"If we're going to save these amazing animals, the Trump administration has to give them the protections they need and stop pushing for dangerous oil drilling in the Arctic," she said. "Any movement away from a transition to renewable energy is a threat to the walrus because sea ice melting is a result of carbon emissions and climate change."