A large number of 830,000 sockeye salmon released into Northern California’s Klamath River are believed to have died after contracting goosebumps, state wildlife officials said Monday.
The condition is caused by a sudden change in pressure. According to the California Department of Fish and Wildlife, it happened as the fish passed through the Iron Gate Dam tunnel.
The tunnel and dam of the same name will be removed later this year.
About 830,000 Chinook salmon fry were the first releases from the Fall Creek Fish Hatchery, a $35 million project designed to support salmon populations in the Klamath River, the wildlife department, known as CDFW, said. said in the statement.
The fish were released on February 26.
It’s unclear how many of the estimated 830,000 cubs died, a department spokesman said, calling it a “high mortality rate.”
CDFW said there are no signs of water quality problems in the river, which is almost 270 miles long and runs through Oregon and Northern California, and another healthy year of coho and Chinook salmon came downstream from the dam.
After that, any other releases will be made downstream until the dam and tunnel are removed, the department said.
The Klamath River was once the third largest salmon-producing river on the West Coast, and dams have since helped the decline. According to the National Oceanic and Atmospheric Administration.
The fish deaths are “another sad reminder of how Klamath River dams have harmed salmon stocks for generations,” CDFW said.