Officials in California thought they were helping to restore the ecosystem of the Klamath River when they released hundreds of thousands of newly hatched Chinook salmon into it, but an unexpected complication caused things to take a horrific turn.
What happened?
In early March, the Guardian reported that, during the largest dam removal project in United States history, the California Department of Fish and Wildlife (CDFW) released 830,000 young Chinook salmon into the 257-mile-long river that flows through Oregon and northern California.
The lower and upper portions of the Klamath River will be connected for the first time in a century when all four hydropower dams are removed, as one has already been demolished and the other three are scheduled to come down later this year.
Unfortunately, hundreds of thousands of Chinook salmon were found dead downstream of the 173-foot Iron Gate dam, which has not yet been demolished. The fish were discovered near a tunnel that had been opened to allow the river to flow freely, as the water pressure inside the tunnel appeared to be too much for the diminutive salmon.
Officials didn't determine exactly how many fish died, but Jordan Traverso, deputy director of communications for the CDFW, said they expected a "very high mortality rate."
The CDFW revealed that the dead fish caught near the tunnel "showed classic signs of gas bubble disease, including popped eyes." The Guardian explained that the condition occurs "when high pressure aerates water, saturating it with natural gases that form microbubbles inside the bodies of the fish."
Why is this concerning?
The CDFW has more than three million fish that it plans to release downstream of the tunnel. It was confirmed that the tunnel was the issue, as officials found Chinook and coho salmon residing downriver from the dams were doing just fine.
"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," the CDFW said in a press release.
Furthermore, salmon and other fish populations have been found to be struggling in various rivers. For instance, thousands of dead salmon were discovered in a dried-up river in Canada in 2022. That particular population of pink salmon could take up to six generations to recover, researchers said, as a combination of less rainfall and higher temperatures created a scenario where these salmon couldn't spawn before their tragic deaths.
What can be done about it?
Traverso said the threat of gas bubble disease will be mitigated when the dams and related infrastructure are fully removed. A study published in October also determined that removing the dams to restore the natural flow of the Klamath River will reduce the hotspots of parasitic and bacterial infections.
However, the two most northerly dams on the river, the Link River dam and the Keno dam in Oregon, will not be removed.
"Those are still major barriers for passage of Chinook salmon," said Mike Orcutt, the fisheries department director at Hoopa Valley Tribe. "There are a lot of challenges still before us."
It will take a continued commitment to new strategies by state and federal agencies to combat the changes brought on by rising global temperatures.
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