830,000 Fall-Run Chinook Salmon Fry Die from Gas Bubble Disease in Klamath River

By Dan Bacher | 

The California Department of Fish and Wildlife (CDFW) announced Saturday morning that hundreds of thousands of fall-run Chinook salmon fry, released for the first time from its Fall Creek Fish Hatchery in Siskiyou County, are “presumed to have succumbed to gas bubble disease in the Klamath River” as the dam removal process moves forward.

The Department said they released approximately 830,000 fall-run Chinook salmon fry on Monday, February 25, into Fall Creek, a tributary of the Klamath River above Iron Gate Dam.

“The fish were hatched at CDFW’s new, $35 million, state-of-the-art Fall Creek Fish Hatchery, which represents California’s long-term commitment to supporting and restoring both Chinook and coho salmon runs on an undammed Klamath River,” the Department said in a statement.

“The salmon fry experienced a large mortality based on monitoring data downstream,” the agency continued. “Indications are the cause of mortality is gas bubble disease that likely occurred as the fry migrated through the Iron Gate Dam tunnel, old infrastructure that is targeted for removal along with the Iron Gate Dam itself later this year. Gas bubble disease results from environmental or physical trauma often associated with severe pressure change.”

“There is no indication the mortality is associated with other Klamath River water quality conditions such as turbidity and dissolved oxygen, which were reading at suitable levels on Feb. 26 and the days prior to release,” the agency argued. “The visual appearance of the dead fry detected by monitoring equipment points to gas bubble disease. Monitoring equipment documented other healthy yearling coho and Chinook salmon that came from downstream of the dam.”

The Department said the problems associated with the Iron Gate Dam tunnel “are temporary and yet another sad reminder of how the Klamath River dams have harmed salmon runs for generations.”

After this big fish kill, CDFW said it will plan all future salmon releases below Iron Gate Dam until this infrastructure is removed.

“Poor habitat conditions caused by the dams and other circumstances such as this are reasons why CDFW conducts releases of hatchery fish at various life stages,” the Department stated.

CDFW’s Fall Creek Fish Hatchery continues to hold approximately 3.27 million healthy, fall-run Chinook salmon, according to the CDFW. Additional releases are planned later in the month.

“The annual fall-run Chinook salmon production goal for the hatchery is to raise and release 3.25 million fish – 1.25 million released as fry, 1.75 million as smolts, and 250,000 as yearlings. The additional stock of fall-run Chinook salmon remaining in the hatchery exceeds the annual production goal and will help offset losses experienced with the initial release of fry,” the CDFW concluded.

This fish kill comes at a critical time for salmon and other fish populations in California. Due to the collapse of fall-run Chinook salmon on the Klamath/Trinity and Sacramento River systems in 2022, all commercial and recreational salmon fishing on the ocean was closed in California and most of Oregon. All recreational fishing was closed on all California rivers last year — and salmon fishing by the Yurok Tribe on the Klamath River and the Hoopa Valley Tribe on the Trinity was restricted to a quota of just 2,000 fish.

The salmon seasons are also likely to be closed or severely restricted this year also, based on relatively low abundance forecasts for Sacramento and Klamath River fall-run Chinook salmon that were released by state and federal fishery scientists at the CDFW’s annual salmon information meeting via webinar yesterday.

The forecasted adult Sacramento Valley fall-run Chinook salmon population number is only 213,622, based on a jack escapement of only 11,933, according to Dr. Michael O’Farrell of NOAA Fisheries. This is the second lowest abundance forecast since the salmon fishing closure of 2008 to 2009. Considering that the goal for spawning escapement is 180,000 this year, this would only leave 33,622 fish for a fishing season.  

The Klamath River fall Chinook abundance forecast is 138,741 for age 3 fish, 39,531 for age 4 fish and 2,409 for age 5 fish. The fishery is now in “overfished” status” and the 2023 regulations applied to the 2024 abundance forecast would result in a natural area spawner prediction of 42,932, according to O’Farrell.

“It’s predecisional to say what the fishing opportunities will be this year,” said Kandice Morgenstern, CDFW environmental scientist, at Friday’s meeting. “A fisheries closure is a possibility, but it’s too early to preclude some fishing this season. It’s too early to say yes or no on a season.”

California representatives will work together to develop a range of recommended ocean fishing season alternatives at the March 6-11 Pacific Fishery Management Council (PFMC) meeting in Fresno, Calif. Final season recommendations will be adopted at the PFMC’s April 6-11 meeting in Seattle, Wash.

For more information related to the salmon preseason process, including contact information, timeline and other opportunities for public engagement, please visit the CDFW’s Ocean Salmon Calendar of Events page.

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