The New York Times
Ice Dwellers Are Finding Less Ice to Dwell On
Nobody knows how many walruses the world holds. Recent surveys by the United States Fish and Wildlife Service and others put the number at roughly 190,000, with the vast majority of walruses in the Pacific half of the Arctic and sub-Arctic Circle and maybe 10 percent in Atlantic waters.
But researchers have little doubt that the figure is on a downward slide, as the polar ice sheet on which the mammal depends for every stage of its life thins and retreats from beneath its flippered feet.
The ice is melting three weeks earlier in the spring than it did 20 years ago, and its re-forming a month later in the fall, said Carleton Ray of the University of Virginia, who has studied walruses since the 1950s.
Theres no question that these changes are very bad for walruses, Dr. Ray added, as they are for other ice dwellers like polar bears and four species of the walruss pinniped kin: the ribbon, ringed, spotted and bearded seals.
Moreover, the retreat of the polar ice cap is luring human industry northward as never before. In February, for example, the Interior Department awarded Royal Dutch Shell the right to drill for oil in the Chukchi Sea off the northwestern shore of Alaska, a heretofore unprospected patch of marine habitat and prime walrus fishing ground.
Like all pinnipeds, walruses are amphibious, finding their sustenance in the sea and their respite on land or ice. They are neither long-distance swimmers nor deep-sea divers, as some whales and elephant seals can be, but hunt in shallow waters around the continental shelf, rarely descending below 100 or 200 feet and re-emerging often to catch their breath. Adult male walruses will leave the ice to summer along the coasts of Siberia and Alaska, but females and their young stay on the floes year-round assuming the ice complies.
Chad Jay of the walrus research program at the Alaska Science Center in Anchorage said that over the last decade, the ice sheet in the Chukchi Sea had been retreating steadily farther north each summer, to the point where it now moves off the continental shelf entirely and ends up over the deep arctic basin, in waters too deep for walruses to forage.
As a result, females and calves have been forced to abandon the ice in midsummer and follow the males to land. The voyage leaves them emaciated and easily panicked. With the slightest disturbance, the herd desperately heads back into the water, often trampling one another to death as they flee.
The ones that take the brunt of it are the calves, Dr. Jay said. Our Russian colleagues have observed thousands of calves killed in episodes of beachside mayhem.
The time has come, Lewis Carrolls walrus said, to talk of many things, among them what the future holds for tusky Odobenus, the pinniped that sings.