Work focuses on supporting fish at Clackamas Hatchery
Staff at the Oregon Department of Fish and Wildlife are working to give spring Chinook salmon at the Clackamas Hatchery a little extra support.
Around 10 years ago, staff at the hatchery at Milo McIver State Park began to see declines in the return rates for hatchery chinook.
"We used to have the highest quality return rates in the Willamette Basin," said Ben Walczak, a biologist with the Oregon Department of Fish and Wildlife.
The return rate for adult hatchery spring Chinook collected at Clackamas Hatchery was 161 in 2018, 229 in 2019, and 784 in 2020. Chinook are still returning this year, but so far this number is at 653.
To reinvigorate the hatchery's stock of spring Chinook, integration of wild and hatchery fish began in late August. Previously, hatchery fish run times were spaced out so they wouldn't be at the same time as the wild fish. But with the integration, hatchery fish run and spawn at the same time as the wild fish.
"(With the integration) the fish have similar genetics and run times as the natural fish, so they mimic the wild fish," he said. "The hatchery was crashing, but the wild population was performing well. There were enough natural fish numbers to put some wild fish into the hatchery production and help with their genetics."
ODFW planned the integration program for two years and collaborated with other agencies, such as Portland General Electric. Walczak will collaborate with geneticists from Oregon State University to publish a paper on the program.
The integration of hatchery and wild fish is part of a larger project that also involved making updates to the hatchery facility so the entire water right could be utilized. As part of this work, ODFW and PGE constructed a new water intake at Estacada Lake to bring a greater volume of water to the hatchery.
The new intake also helps reduce the presence of pathogens at the hatchery, which lowers the risk of disease transfer between river basins.
Supporting hatchery and wild fish
Walczak described the integration of the wild and hatchery fish as a balancing act.
"We want to make sure we're not compromising the wild population while providing harvest opportunities," he said, noting that the Clackamas is a significant driver to the Willamette River Basin.
ODWF is maintaining a record of every fish participating in the program, along with their genetics.
"When the fish return, we'll take the genetics and compare them," Walczak said, adding that similar integration work has been done with spring Chinook on the neighboring Sandy River.
"It's getting more and more common."
Walczak estimated that the hatchery would begin seeing any potential effects from the integration work three to five years from now.
"The hardest part is waiting for more data to make decisions," he said, discussing the importance of not acting prematurely. "If you make a mistake, you can't take things back. We have to be more conservative because we can't take things back."
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