“Crying” walrus pups may be stranded thanks to global warming, researchers say
and World Science staff
Melting Arctic Ocean ice may be leaving walrus pups stranded, according to researchers.
“We were on a station for 24 hours, and the calves would be swimming around us crying. We couldn’t rescue them,” said Carin Ashjian, a member of the research team.and biologist at Woods Hole Oceanographic Institution in Woods Hole, Mass.
Most scientists believe widespread melting of polar ices is due to global warming, a gradual increase in the Earth’s temperature caused by the burning of fossil fuels.
Ashjian’s group reported an unprecedented number of unaccompanied walrus calves in the ocean. The melting ice may be forcing mothers to abandon their pups as the mothers follow the rapidly retreating ice edge north, according to the scientists.
Rsearchers aboard the U.S. Coast Guard icebreaker Healy reported nine lone walrus calves swimming in deep water far from shore during a cruise in the Canada Basin in the summer of 2004. The calves were likely to drown or starve, the scientists said.
Lone walrus calves far from shore had not been described before, the researchers wrote in the April issue of the research journal Aquatic Mammals. The sightings suggest that increased polar warming may lead to decreases in the walrus population.
The researchers reported evidence of warmer ocean temperatures that may have rapidly melted seasonal sea ice over the shallow continental shelf where walruses dive to eat bottom-dwelling animals such as clams and crabs. Walrus need the ice to rest and to leave the while mothers feed. Ice remained over very deep water.
“A significant population decline of this species could occur,” the research team wrote. The lead author of the study is Lee W. Cooper, a biogeochemist at the University of Tennessee.
Adult Pacific walrus, Odobenus rosmarus divergens, forage for food by diving as far as 200 meters about (630 feet) to the seafloor and using sensitive facial bristles to find prey. Sea ice normally forms over the continental shelf north of Alaska and persists in summer, the researchers said. Adult walrus use the sea ice as a resting platform; mothers leave the calves there and dive to the bottom for food.
“The young can’t forage for themselves,” Ashjian said. “They don’t know how to eat,” and are dependent on their mothers’ milk for up to two years.
The researchers measured a mass of water as warm as 44°F (7°C) moving onto parts of the shelf from the Bering Sea to the south in 2004. This warm-water intrusion was more than six degrees higher than temperatures at the same time and location in 2002, they said.
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