Bering Sea cold pool keeps fish from migrating
As scientists observed climate warming in the Bering Sea, they suspected valuable commercial fish species such as Pacific cod and walleye pollock would move north toward the Bering Strait and into the Arctic Ocean.
The Associated Press
ANCHORAGE — As scientists observed climate warming in the Bering Sea, they suspected valuable commercial fish species such as Pacific cod and walleye pollock would move north toward the Bering Strait and into the Arctic Ocean.
But that's likely decades off, according to one surprising result from a study of the sea north of the Aleutian Islands.
Scientists say a pool of cold water in the northern Bering Sea has been a locked door to the northward migration of pollock and cod, the fish harvested for America's fish sticks and fast-food sandwiches.
"Our original hypothesis was wrong, and we think they won't have habitat to occupy northward in the northern Bering Sea," said Mike Sigler of Juneau, a marine biologist with the Alaska Fisheries Science Center, part of the National Oceanic and Atmospheric Administration.
Water along the ocean floor where pollock live has been kept cold by the layer of sea ice that forms every winter on the surface of the northern Bering Sea. That ice is expected to persist even with climate warming. Cold water sets up below the ice layer and remains cold throughout the summer.
"What it looks like at the moment is that the northern Bering Sea — and north to us is north of St. Matthew Island — looks like it is going to stay cold," said physical oceanographer Phyllis Stabeno of NOAA's Pacific Marine Environmental Laboratory in Seattle.
Sigler and Stabeno are two of more than 100 principal investigators taking part in a $52 million study of the eastern Bering Sea ecosystem. "We're in the analysis and synthesis stage to complete the project," Sigler said, of the study that began in 2007.
Commercial fishermen in the Bering Sea and Aleutian Islands this year were allowed to catch 2.8 billion pounds of pollock, and nearly 510 million pounds of Pacific cod.
Researchers had documented sub-arctic species including cod and pollock moving north within the Bering and assumed that would continue, until the discovery of the cold pool.
"The hypothesis that we had worked with for years was that as warming occurs, the Bering Sea would kind of warm uniformly," Stabeno said, meaning that fish species would move north. And that would have complicated matters for the commercial fishing fleet, increasing calls for a Coast Guard base, a deep-water port and other infrastructure in northwest Alaska.
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