Report: Algae toxin poses health risk in Klamath reservoir fish

By Jeff Barnard
Grants Pass, Oregon (AP) 4-08

An analysis shows tissue samples from a popular game fish found in two Klamath River reservoirs and mussels from the Klamath River contain algae toxins at levels high enough to pose a risk to public health.

The Karuk Tribe commissioned the analysis as part of its campaign to remove dams on the Klamath River to help salmon.

The analysis by Aquatic Ecosystems Sciences in Ashland recommends that warnings be posted against eating yellow perch from Copco and Iron Gate reservoirs and freshwater mussels from the river during summer when the algae blooms are going on. The perch are a popular game fish and the mussels are a traditional food for tribal members.

The toxins come from the blue-green algae known as Microcystis aeruginosa. Testing by the Karuk tribe showed levels exceeding World Health Organization guidelines in the Copco Reservoir in 2001.

The Copco and Iron Gate reservoirs are regularly posted with health warnings against swimming in or drinking the water, and last summer warnings were posted far downstream.

Microcystis aeruginosa commonly blooms in warm, slow-moving waters with high levels of phosphorus and nitrogen, nutrients commonly running off agricultural land. The toxin affects the liver.

Spokesman Craig Tucker said the tribe is seeking a public health warning from California authorities against eating fish and mussels.

The analysis found algae toxins in the livers and fillets of yellow perch from Copco and Iron Gate reservoirs, the flesh of mussels from the Klamath River below the dams, and the livers of young salmon in the Iron Gate fish hatchery. The reservoirs are in Northern California near the Oregon border.

Levels exceeded guidelines in the scientific literature for human consumption, said Jacob Kann of Aquatic Ecosystem Sciences. They were highest when the algae blooms were most prevalent, in summer.

The toxin in the perch and salmon is not high enough to kill the fish, but could be enough to weaken them, Kann noted.

The tissue samples were gathered by the California Department of Fish and Game under contract to the California Water Board with funding from the U.S. Environmental Protection Agency.