Abandoned by the mothers too far offshore to swim back to land, walrus calves would likely succumb to starvation and drowning. (Photo by Phil Alatalo, Woods Hole Oceanographic Institution)
Stepping aboard the U. S. Coast Guard Cutter Healy to explore the Arctic Ocean, Carin Ashjian expected to ride the sea’s winds and swells, but not an emotional roller coaster. In spring and summer of 2004, Ashjian and colleagues were investigating the potential impacts of a warming climate on the delicately balanced Arctic Ocean ecosystem, when they discovered an unexpected phenomenon: nine sightings of baby walruses swimming alone far from shore—apparently abandoned by their nursing mothers.
“The young can’t forage for themselves and are dependent on their mothers’ milk for up to two years,” said Ashjian, a biologist at Woods Hole Oceanographic Institution. The lone calves, about two months old and too far offshore to swim back to land, would likely succumb to starvation and drowning, the researchers concluded.
“We would sail up to a particular location and stay there for 24 hours at a time, and one or two of these pups would swim up to us, and the poor little guys would just bark at us for hours on end,” Ashjian said. “It was really awful. I wouldn’t go outside.”
Adult walruses forage for clams, snails, crabs, worms, and other invertebrate animals on the shallow seafloor of the continental shelf, diving to depths of no more than 656 feet (200 meters). Walrus mothers leave their calves on sea ice while they dive, returning to nurse them. In short, walruses depend on sea ice that usually persists above shallow nearshore waters in summers, and in 2004, the ice disappeared. The researchers observed a mass of water as warm as 44°F (7°C) over the continental shelves of the Chukchi and Beaufort Seas—more than six degrees higher than temperatures measured in the same region in 2002. Sampling with plankton nets, they found zooplankton species characteristic of warmer, more southern waters.
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