Pacific walruses have long relied on floating sea ice in the Arctic. They use it as a resting place between dives as they forage for shrimp, worms, and mollusks on the ocean floor. Female walruses also give birth on these ice platforms and raise their pups there.
But thanks to global warming, all that Arctic sea ice is dwindling. And so, in recent summers, many walruses have been seeking refuge on the northern shores of Alaska and Russia instead.
This September, scientists observed one of the biggest land haul-outs in recent memory in northern Alaska — with an estimated 35,000 walruses crowding the shore of a remote barrier island near Pt. Lay. Surveyors from the National Oceanic and Atmospheric Administration photographed the event on September 13 during their annual aerial survey of Arctic marine mammals:
This seems to be an increasingly common occurrence, and the US Geological Survey has blamed it on climate change.
Major walrus haul-outs have now been observed in Alaska in six of the past eight years — at a time when Arctic sea ice has been shrinking. In 2010, some 20,000 walruses came ashore near Pt. Lay. In 2011, nearly 30,000 came ashore. In 2013, another 10,000 came ashore.
Several thousand walruses were killed in stampedes last year after the disappearance of the ice caused them to crowd onto the shoreline in extraordinary numbers, deaths some scientists see as another alarming consequence of global warming.
The deaths took place during the late summer and fall on the Russian side of the Bering Strait, which separates Alaska from Russia.
"It was a pretty sobering year — tough on walruses," said Joel Garlach-Miller, a walrus expert for the U.S. Fish and Wildlife Service.
Unlike seals, walruses cannot swim indefinitely. The big, tusked mammals typically clamber onto the sea ice to rest, or haul themselves onto land for just a few weeks at a time. But when the ice disappeared in the Chukchi Sea last year because of warm summer weather, ocean currents and persistent eastern winds, walruses came ashore earlier and stayed longer, congregating in extremely high numbers, with herds as big as 40,000 at Point Shmidt.
Walruses are vulnerable to stampedes when they gather in such large numbers. The appearance of a polar bear, a hunter or a low-flying airplane can send them rushing to the water, crushing older adults and most of their young pups.
The sad story of the Arctic animals decline continues. Most people are not aware of it and I wonder how much they would care if they knew.