On Thin Ice
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“Could you realistically put 200 to 500 foreign compounds into an organism and expect them to have absolutely no effect?” asks Derocher. “I would be happier if I could find no evidence of pollution affecting polar bears, but so far, the data suggest otherwise.”
While toxic substances are jeopardizing bears, the melting of the Arctic is a more immediate threat to their survival. In Canada’s western Hudson Bay, the sea ice where they hunt seals breaks up three weeks earlier now than 30 years ago, polar bears have declined from 1,200 in 1985 to fewer than 950 in 2004. That same year, marine biologists in Alaska reported finding four drowned polar bears, perhaps because they were unable to swim long distances to reach solid ice. Forty wildlife scientists, representing all five nations inhabited by polar bears, adopted a resolution last June declaring that the bears are “susceptible to the effects of pollutants” and those effects are exacerbated by the stresses of global warming.
In 20 years of Arctic research, first with the Norwegian Polar Institute and now with the University of Alberta, Derocher has captured and tested more than 4,000 bears. It is dangerous work, but the only way that scientists can monitor their health. Scanning the ice below, he has picked up the bear family’s trail, and soon the mother and cubs are below the helicopter. In the backseat, Norwegian scientist Magnus Andersen injects a syringe of tranquilizer into a dart and screws it onto a shotgun. The helicopter spins in circles perilously close to the ground to give Andersen a clear shot. He leans out the open door, takes aim, and fires. Hit in the rump, the mother wobbles, but she isn’t going down. Andersen readies another syringe and fires again. The bear lies down on her stomach, one giant paw splayed back. The two cubs nuzzle her, trying to awaken her, then curl up beside her.
The cubs, only four months old, are wide-eyed and curious as the helicopter lands and the scientists cautiously approach on foot, their boots crunching in the crusty snow. Derocher sets down his black toolbox, removes some dental pliers, and opens the sleeping bear’s jaw, deftly extracting a tooth the size of a cribbage peg that will be used to confirm her age. Andersen slices a quarter-inch-diameter plug of blubber from her rump with a biopsy tool and siphons a tube of blood from a vein in her inner thigh. Then Derocher kneels beside the mother and milks her to sample the creamy liquid she is feeding her sons. The milk, fat, and blood will be analyzed for a suite of chemicals. Before departing, the scientists tranquilize the cubs. The threesome will snooze for a couple of hours, then shake off the drowsiness and continue on their way.
Aloft again, the helicopter glides north between Svalbard’s snow-draped peaks until Derocher spots more tracks—this time, a mother and two yearlings. Relishing the clarity of spring’s eternal light, the scientists know that polar winter will soon descend, plunging Svalbard into darkness again. Into that darkness the next generation of ice bears will be born—to a very uncertain future.
Photo: AP/Wide World Photos
