Saturday, January 7, 2012

Baby harp seals being drowned, crushed amid melting ice

Dave Mosher in National Geographic News: Harp seal pups are taking a hit due to global warming, according to the first study of its kind. Ice-busting storms and warmer waters fueled by rising temperatures are diminishing the ice cover that harp seals need to survive during their first vulnerable weeks of life.

Without thick, solid ice expanses, seal babies drown or are crushed by broken-up chunks of ice. For the harp seals, "good ice is about 30 to 70 centimeters [12 to 28 inches] thick and covers 60 to 90 percent of the water," said marine biologist Garry Stenson, who works for Canada's Federal Department of Fisheries and Oceans and helps to monitor and assess harp seal populations.

But ice cover in the sub-Arctic and North Atlantic Ocean has declined about 6 percent per decade since the 1970s. (Read "The Big Thaw" in National Geographic magazine.) And as climate change continues to degrade the amount of good ice, the average pup survival rate is likely to drop over the years, experts say.

"Some years, when there's poor ice in a given pupping ground, essentially all of the pups don't make it," said study leader David Johnston, a marine biologist at Duke University. In 2007, for example, more than 75 percent of pups overall perished because of poor ice conditions—in 2010, almost none survived, Johnston said....

A young harp seal shot by Matthieu Godbout, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

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