Number of fish deaths in Klamath questioned

More than twice as many salmon may have died in the unusually low, warm water of the Klamath in 2002 as biologists first thought, according to new findings released Friday by the California Department of Fish and Game.

The losses may have represented nearly half of the salmon expected to return to the river and its tributaries. The report could further heighten contention surrounding diversions of water from the Klamath River system to irrigate farms in the Klamath Project on the Oregon-California border.

It concludes that while authorities said at least 33,000 salmon had died, the number may have been as high as 80,000. The true toll was probably somewhere in between, said Gary Stacey of the Department of Fish and Game.

California biologists are worried about Klamath River salmon this year because river conditions are similar to those during the 2002 die-off, one of the largest mass deaths of adult salmon in U.S. history.

More than 1,000 project farms had much of their irrigation water curtailed in 2001 due to protections for endangered suckers in Oregon's Upper Klamath Lake and threatened coho salmon in the Klamath River. In 2002, however, irrigation was largely restored.

Environmental groups and Native American tribes blame irrigation diversions for causing the fish deaths by leaving so little water in the river that disease ran rampant among crowded fish. But irrigators respond that a combination of unusual factors, including warm weather and an unusually large return of salmon, conspired to kill the fish.

The report was reviewed by other scientists and reflects the state's final word on the die-off. It says a combination of low water, high temperatures, many salmon and disease all contributed.

But it also says river flows are "the only controllable factor and tool available in the Klamath Basin" to reduce the risk of such fish kills. Increased fall flows when salmon are entering the river could improve conditions enough to help them survive, it says.

A comparison of numbers of salmon expected to return up the Trinity River, a tributary to the Klamath, in the fall of 2002, to fish that returned in the spring of the same year led state officials to conclude the die-off toll may have been underestimated.

Michael Milstein: 503-294-7689; michaelmilstein@news.oregonian.com

 

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