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Northwest Diet Switch has Scientists Concerned about Orcas

© Matt Villano

Cuddly sea otters in Alaska's Aleutian Islands have redefined the phrase ''sitting duck.'' The munchkin sea mammals dive for dinner, then, in a Kodak moment, float on their backs above the kelp forest to eat. Using rocks for tools, they precociously break open mussels and barnacles and delicately extract meat from spiny sea urchins.

Cue up the music from ''Jaws.'' As the ominous ''dah-dah-dah-dah'' rises toward a climax, an enormous killer whale bursts through the kelp fronds to gobble a sea otter whole.

''It actually looks like darn easy pickings,'' said Terrie Williams, a biology professor at the University of California at Santa Cruz who has witnessed the startling spectacle.

Indeed, something very strange is going on in the Bering Sea, the vast, cold expanse that lies between Alaska and Siberia. Killer whales have suddenly switched from eating big Steller sea lions to itty-bitty sea otters, the equivalent of furry cocktail wienies. The diet switch was prompted by the plummeting population of western sea lions, some scientists say. Other marine mammals such as northern fur seals are also doing poorly. And some of the most commercially valuable inhabitants of the sea, king crabs and shrimp, have nearly vanished.

In fact, a federal judge in Seattle is so concerned about the ecological changes that last week, he banished fishermen from harvesting groundfish over a large area of the Bering Sea and the Gulf of Alaska in an effort to protect the food supply of the dwindling sea lions. US District Judge Thomas S. Zilly's move, one of the toughest steps ever taken under the Endangered Species Act, is expected to cost fishermen $93 million in lost revenue by the end of the year.

''People are in shock,'' Chris Blackburn, who represents the fishing industry in Kodiak, Alaska, told the Seattle Times. ''A community on an island: Fishing is what we do.'' But Zilly's ruling noted that, without strong actions, the sea lions face extinction after more than 3 million years of inhabiting the North Pacific, including the Gulf of Alaska.

It's not at all clear, however, that humans are to blame in any direct sense for the upheaval in the Bering Sea and the Gulf of Alaska, neighboring water bodies separated by the Aleutian Islands. Although the Exxon Valdez oil spill in 1989 was temporarily devastating, life in the Gulf of Alaska has largely recovered. Likewise, fishing has greatly increased - from just 27,000 metric tons of groundfish in the 1950s caught in Alaskan waters to 2.1 million metric tons removed annually in the 1990s - but it has gone hand in hand with soaring groundfish stocks.