NOAA - Ocean Conditions First Among Multiple Causes Of Sacramento Salmon Run Crash

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The collapse of Sacramento River salmon runs that led to the close of coastal fisheries in Oregon in recent years can be largely traced to poor ocean conditions. That is the conclusion of a recent report (PDF) from the National Oceanic and Atmospheric Association.

But the report points out that the salmon who were hurt by warm sea-surface temperatures and low food supply were already suffering from declining freshwater conditions in the Sacramento River basin, where water diversions for agriculture have hurt fish.

"All of the evidence that we could find points to ocean conditions as being the proximate cause of the poor performance of the 2004 and 2005 broods" of Sacramento River Fall Chinook, the report said. "We recognize, however, that the rapid and likely temporary deterioration in ocean conditions is acting on top of a long-term, steady degradation of the freshwater and estuarine environment."

Those findings are important because the status of endangered fish in the Sacramento affect everything from the California's massive Central Valley agricultural industry to Oregon's coastal fishing communities. Environmentalists and others have long pointed to the de-watering of the Sacramento-San Joaquin River Delta as a primary cause for salmon decline.

EDIT

http://www.oregonlive.com/environment/index.ssf/2009/03/poor_ocean_conditions_hurt_sac.html