Subject: Pollution and polar bears (fwd)

Mike Williamson (
Sat, 29 Aug 1998 17:12:18 -0400 (EDT)

Date: Sat, 29 Aug 1998 06:28:28 -0700
From: MARMAM Editors <marmamed@UVic.CA>
Reply-To: Marine Mammals Research and Conservation Discussion
Subject: newsclip - polar bears (fwd)

Drifting pollution affecting Arctic wildlife

August 17, 1998

By Environmental News Network staff (ENN) -- The warming of
the Canadian Arctic region over the last two decades could be making
life worse for polar bears, according to research published
recently in New Scientist magazine.

Researchers Nick Lunn and Dennis Andriashek of the Canadian Wildlife
Service have been studying polar bears around Churchill on the shores of
Hudson Bay in Canada. Their study is one of the most detailed audits of
any wild animal population anywhere, according to the magazine.

Twice a year, in March and September, Lunn and Andriashek go
bear-tagging. Recently, their research has revealed that the bears they
study have been growing thinner and there are fewer new cubs. The
researchers are blaming changes in the offshore ice for these effects
and say a catastrophe may be imminent.

Polar bears spend much of their lives on the ice floes along the
Canadian coast. They feed mainly on young ringed seals and life is
generally easy. But as the ice melts and they are forced onto land,
finding food gets more difficult. With the food scarcity, adult bears
may lose as much as a third of its body weight over the summer,
according to the article.

This weight loss affects their reproduction. Annual births per adult
dropped from 0.99 to 0.84 from the early 1980s to now. During the same
period, average weight for the bears also declined according to New

Some scientists theorize that the bears are being affected by pollutants
such as PCBs, which travel to polar regions in the atmosphere and then
accumulate in the food chain.

Last year, researchers in Norway's remote Svalbard islands reported they
found seven female polar bears with vestigial male organs. Research team
leader Andrew Derocher believed the anomaly may have been caused by
toxic chemicals.

The Svalbard archipelago are at a crossroads of air and ocean currents
bringing pollution from distant industrial sites in Europe, North
America and even Asia.

PCBs dissolve readily in animal fat, such as blubber, and stay there. A
polar bear's favorite food is seal blubber.

However, the level of PCBs -- polychlorinated biphenyls -- in the
Svalbards is at least 2.5 times higher than in Canada's polar bear
territory, Derocher said.

Ian Stirling, head of the Churchill research program, believes that
instead of PCBs, a more likely explanation is the melting of ice floes
in the Canadian region.

"The final weeks before the ice melts in Hudson Bay are a critical time
for the bears -- and possibly the key to their continued survival. Adult
bears out on the ice do most of their feeding at this time," according
to New Scientist.

"Stirling estimated that if the ice broke up even one week earlier than
normal, typical female fears would come ashore 10 kilograms lighter and
return at the end of the summer 34 kilograms lighter. They would produce
and wean fewer cubs.

In the short term, global warming could be good for bears further north,
says Stirling, because the break-up of permanent ice would provide a
better habitat for seals. But round Hudson Bay, he believes the bears
could already be on a knife-edge. "The first impact (of warming) on
polar bears will be felt at their southern limit, in Hudson Bay," he

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