Alaska Sea Otters' Disappearance a Mystery

By Yereth Rosen

ANCHORAGE, Alaska (Reuters) - When Russian explorers first saw sea otters bobbing in the waters off Alaska's Aleutian Islands in the mid-18th century, they knew they had discovered a money maker.

The otters' fur "is so far superior in length, beauty, blackness and gloss of hair to the river otters' pelts that these can scarcely be compared to it," wrote German naturalist Georg Steller, who accompanied legendary mariner Vitus Bering on his Alaska expeditions.

Russian and American hunters later wiped out nearly all of Alaska's sea otters, whose luxurious fur became known as "soft gold." The otters were saved from extinction after a 1911 treaty banned the commercial hunt.

But sea otters are once again vanishing from Alaska's 1,000-mile Aleutian chain and other parts of southwestern Alaska. This time, there is no obvious explanation.

Alaska's sea otter population numbered 100,000 to 137,000 in the 1980s, with its core in the Aleutians and western Alaska. But numbers fell 70 percent from 1992 to 2000, according to the U.S. Fish and Wildlife Service. Some Aleutian populations are down to just a few thousand, about 5 percent of 1980s' levels, the agency said.

Their disappearance could cause wider ecological harm by upsetting the food chain in the icy coastal waters.

Otters eat sea urchins, which feed on kelp. Without the otters to control urchin populations, undersea kelp forests are being mowed down, scientists warn.

"Now across the Aleutian archipelago there are these vast areas that are just deforested kelp beds," said Jim Estes, a Santa Cruz, California-based U.S. Geological Survey ecologist and Alaska sea otter expert. That could hurt fish that dwell in kelp beds, Estes said.

NO OBVIOUS ANSWERS

Although there are no obvious answers, some theories have emerged to explain the sea otters' problems.

One theory blames climate change for disrupting marine prey-predator balances. Another blames the accumulation of contaminants, including those carried from southern latitudes by marine and atmospheric currents. And some say conflicts with commercial vessels may be contributing to the decline.

One controversial theory, advanced by Estes and others, claims widespread commercial whaling until the 1970s triggered cascading collapses of North Pacific marine mammals. Under this theory, killer whales are now hunting sea otters because their normal prey -- other whales, sea lions and harbor seals -- are scarce.

Many environmentalists accuse the Bush administration of not doing enough to protect the otters.