Scientists say they believe toxins from a blue-green algae plaguing lakes and rivers around the West are harming an endangered fish in the Klamath Basin, adding another obstacle to restoring species that have forced irrigation shutoffs for farmers.
U.S. Geological Survey fish biologist Scott VanderKooi said Wednesday that liver damage detected in young Lost River and shortnosed suckers in Upper Klamath Lake appears to have been caused by the algae known as microsystin, which regularly shows up in the lake.
"We have symptoms in juvenile suckers consistent with exposure to these same toxins," VanderKooi said. "It was something we've suspected for some time. We didn't have evidence of it. Now we are starting to see more evidence of it."
He said more analysis is needed on liver samples to determine that the toxin is actually present.
Summer blooms of the toxic algae have been reported from coast to coast, prompting health warnings for people to stay out of the water. This year 21 lakes and streams in Oregon were posted, and at least one dog died after drinking tainted water. Symptoms in people include eye and skin irritation, vomiting and stomach cramps, diarrhea, fever, headache, pains in muscles and joints, and weakness.
The algae toxin has been detected in other fish downstream from Upper Klamath Lake. California Department of Fish and Game tests found it in the livers of yellow perch in Copco and Irongate reservoirs, as well as Klamath River steelhead, according to a report by Aquatic Ecosystem Sciences LLC of Ashland for the Karuk Tribe.
Craig Tucker, Klamath campaign director for the Karuk Tribe, said the toxin is more likely to affect resident fish in lakes, where they have prolonged exposure to it, than salmon and steelhead that are migrating along a river.
Upper Klamath Lake is the main irrigation reservoir for more than 1,000 farms in the upper Klamath Basin, and a drought in 2001 forced irrigation cutbacks to keep enough water in the lake for the endangered fish.
The algae thrives in summer in water polluted with nutrients such as cow manure and fertilizer washing off farmland. When blooms subside, the toxin dissipates.
Millions of dollars have been spent on improving habitat and the irrigation system to benefit the endangered suckers.