September 10, 2008

Oceanic Cycle Creates Feast For West Coast Sea Life

An oceanographer with the National Oceanic and Atmospheric Administration (NOAA) said Tuesday a change in atmospheric conditions has generated a feast for West Coast salmon and other marine life off the U.S. west coast.

The change last fall in a cycle known as the Pacific Decadal Oscillation means that cold water from the Gulf of Alaska is now being carried down the west coast, bringing with it an abundance of tiny creatures called copepods that form the basis of the food chain, said Bill Peterson of NOAA Fisheries in Newport, Oregon.   

The change in cycle, which Peterson predicted last spring, reverses a trend that essentially shutdown all West Coast salmon fishing this summer.

Peterson isn't sure how long the phenomenon will last, but said surveys of ocean chinook salmon in June discovered an abundance of yearling juveniles, which should grow become abundant supplies of adults by 2010. Coho surveys will begin in two weeks.

While the cycle previously lasted up to two decades, it has recently taken only about four years to change.  But no one can be sure what the future will bring, Peterson said.

Oregon Department of Fish and Wildlife fisheries chief Ed Bowles said salmon that spend most of their time close to the coast, such as coho, fall chinook and Willamette River spring chinook, should benefit most.  But other sea life, including lingcod, crab, rockfish, sea birds and others, are also recovering.

But Bowles was nevertheless guarded in his appraisal.

"Overall, we are seeing more years of poor ocean conditions than we are good," he told Reuters.

"This is a welcome respite in what more typically has been discouraging news."

Bowles added that Columbia River salmon have also gained from court-ordered increases in the water spilled over hydroelectric dams.  The practice accelerates their migration downriver to the ocean, increasing the number of those that survive.

Peterson said the Pacific Decadal Oscillation changed last November, which translated into the best conditions for West Coast fisheries since 1999, the beginning of several good years for fish.  The increase in copepods meant more food for baitfish like sand lance and smelt, which serve as food for larger fish such as salmon.

However, in 2005 that changed, resulting in starvation conditions for young salmon migrating from streams to the ocean.

Three years later, their numbers were so small that federal authorities all but shut down commercial and sport fishing off the coasts of California, Washington and Oregon. Authorities are now investigating a variety of factors that could have played a role in the collapse of salmon returns from British Columbia to California. Irrigation withdrawals from California's Sacramento-San Joaquin Delta are the chief suspect, with salmon from the Sacramento River experiencing some of the fiercest declines. A federal judge is now working to limit harm on young salmon from irrigation withdrawals from the Sacramento-San Joaquin Delta.


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