Friday, January 27, 2012

Harp Seals On Thin Ice After 32 Years of Warming

Warming in the North Atlantic over the last 32 years has significantly reduced winter sea ice cover in harp seal breeding grounds, resulting in sharply higher death rates among seal pups in recent years, according to a new Duke University-led study.

"The kind of mortality we're seeing in eastern Canada is dramatic. Entire year-classes may be disappearing from the population in low ice years -- essentially all of the pups die," said David W. Johnston, research scientist at the Duke University Marine Lab. "It calls into question the resilience of the population."

The study, recently published in the peer-reviewed journal PLoS ONE, is the first to show that seasonal sea ice cover in all four harp seal breeding regions in the North Atlantic has declined by up to 6 percent a decade since 1979, when satellite records of ice conditions in the region began.

Harp seals rely on stable winter sea ice as safe places to give birth and nurse their young until the pups can swim and hunt on their own. Female seals typically seek out the thickest, oldest ice packs in sub-Arctic waters each February and March, and have adapted to the spring melt by developing unusually short, 12-day nursing periods. Read More