Diseased fish found in Klamath River

Diseased fish found in Klamath River
Herald & News

August 5, 2014

More than three-quarters of juvenile chinook salmon recently surveyed in the Klamath River are diseased, according to a report by the California-Nevada Fish Health Center.

The center has examined juvenile salmon from four reaches of the Klamath River since March. According to the report, the parasite Ceratomyxa shasta has been detected in 76.5 percent of the fish tested. Parvicapsula minibicornis has been detected in 87 percent of the fish.

According to report data, in 2013 C. shasta was found in fish during six out of the 12 weeks the river was surveyed. In 2014, the parasite was found in all 12 weeks. The parasite spiked in late June, increasing from a less than 20 percent presence one week to a roughly 95 percent presence the next.

Last year during that time, surveys indicated the parasite was present in only 5 percent of the fish.

Nick Hetrick, a supervisory fish biologist for the Arcata Fish and Wildlife, said P. minibicornis infections make salmon more vulnerable to C. shasta infections, which can be lethal.

Hetrick said C. shasta infections attack fish intestinal tracts and cause the abdomen to bloat.

“It almost turns the fish into a sponge. It’s fairly obvious when a fish is infected,” Hetrick said.

Hetrick pointed out that C. shasta is completely dependent on temperature — fish can be infected and not exhibit symptoms. Once water temperatures crest 57 degrees, the disease advances quickly, he said.

“The warmer the water, the faster they multiply,” said Sara Borok, an environmental scientist for the California Department of Fish and Wildlife. “The lower the water, the more crowded the fish are and the faster the disease spreads.”

Fish were collected by biologists with the Karuk and Yurok tribes, and the U.S. Fish and Wildlife Service. The fish health center coordinated the effort and provided laboratory support, the report said.