A large number of about 830,000 salmon fry released into Northern California’s Klamath River are believed to have died after they contracted gas bubble disease, state wildlife officials said Monday.
The condition is caused by extreme changes in pressure. It happened as the fish passed through the Iron Gate Dam tunnel, the California Fish and Wildlife Department said.
The tunnel and the dam of the same name will be removed later this year.
The approximately 830,000 Chinook salmon fry are the first to be released from the Fall Creek Fish Hatchery, a $35 million project designed to support salmon populations in the Klamath River once it is fully stocked, the department said. wildlife, known as CDFW, in a statement.
The fish were released on February 26.
How many of the approximately 830,000 fry died was unclear, a spokesman for the department said, but it was called a “high mortality rate.”
There is no indication of water quality problems in the river, which is nearly 270 miles long and travels from Oregon and through Northern California, and other healthy yearling coho and Chinook salmon come downstream from the dam, said the CDFW.
From now until the dam and the tunnel are removed, any other releases will be carried out downstream, the department said.
The Klamath River was once the third-largest salmon-producing river on the West Coast, and dams have contributed to the decline since then, according to the National Oceanic and Atmospheric Administration.
The fish deaths are “another sad reminder of how Klamath River dams have harmed salmon runs for generations,” CDFW said.
This article was originally published on NBCNews.com
