The evidence of the impact of global warming on animal populations continues to pile up. Wildlife biologists have been noting for several years that Pacific walruses have been foraging in more coastal areas and using beaches for resting as their usual Arctic sea ice habitats melt away. However, it now appears the problem is getting progressively worse, and has led to massive accumulations of walruses packed onto a beach, a new behavior only seen in the species since 2011.
Before the last few years, walruses typically used offshore ice floes in the northern Chuckchi Sea as places to rest in between dives to the bottom of the shallow bay waters where the animals feed during the summer and autumn. But given the ice floes all melted by early September this year, the walruses have had no choice but to come onshore to rest. A remote barrier island near Pt. Lay, Alaska has apparently become a favorite congregation spot. More than 35,000 walruses were reported congregating on a single beach on the barrier island earlier this week in an annual arctic marine mammal aerial survey conducted by federal wildlife agencies.
Potential for stampedes
A spokeswoman for the U.S. Fish and Wildlife Service told the media the walruses were initially seen September 13th. She also noted that observers last week saw about 50 carcasses on the beach, likely animals killed in a stampede, and that the Service was performing necropsies to determine the cause of death.
More on walruses
Zoologists say that Pacific walruses typically spend the winter in the Bering Sea. The females give birth on sea ice and use the ice floes as diving platforms to forage for snails, clams and worms on the shallow continental shelf sea floor.
Of note, walruses cannot swim indefinitely and must rest regularly. They frequently use their tusks pull themselves onto ice or rocks to rest.
However, during the summer, the edge of the sea ice moves to the north. Female walruses and their young follow the sea ice into the Chukchi Sea, which is almost due north of the Bering Strait.
The problem is that the sea ice has receded north beyond shallow continental shelf waters and into Arctic Ocean water the last few years. The depth of the water there exceeds 1.5 miles, which means walruses cannot dive to the bottom, and why they have had to resort to congregating onshore.