Record number of spring chinook return to the Deschutes

June 24, 2021
Record number of spring chinook return to the Deschutes

Almost 60 spring Chinook have made their way to the Pelton fish trap, and moved above the dams

It’s been an uphill battle for fish in the Deschutes River — their historic numbers have fallen due to the construction of dams and diversions that have disrupted their native habitat. But this year a project to help recover their numbers is finally showing signs of success.

So far this year, 59 spring chinook salmon have been collected from the Pelton Trap and released above the Pelton Round Butte dam complex, according to Allison Dobscha, a spokesperson for Portland General Electric. That’s a record number for the fish transfer project.

Fish habitats in the Upper Deschutes River were decimated over the past century, partially due to farming and agriculture. But the biggest culprit was the installation of a series of dams along the Lower Deschutes west of Madras. The dams blocked access to the upper reaches of the river and also altered the temperature of the river water.

“This is the best return of spring chinook we’ve experienced since adults started returning to the project in 2011,” said Dobscha. “We’ve seen returns in the low fifties before, but 59 surpasses those records and we still have weeks to go in the run.”

The project to return fish to the river revolves around the Selective Water Withdrawal tower at the Pelton Round Butte dam complex, part of a hydropower system on the Lower Deschutes that powers 150,000 homes. The complex, jointly owned by Portland General Electric and the Confederated Tribes of Warm Springs, includes three dams along a 20-mile stretch of the Deschutes River.

The tower accomplishes two tasks simultaneously — both creating more natural seasonal temperature patterns in the river and collecting fish to be transferred downstream. A trap below the dams collects fish for transfer upstream.

For decades the fish migration route was severed by the dams and it will take years to reestablish the route, so any improvement in returning fish numbers is a positive sign that the system offers tangible benefits.

The 59 chinook released into the Upper Deschutes were adults that had previously been collected as smolts from the Selective Water Withdrawal tower. Smolts are juvenile fish in the stage of their lifecycle when they are preparing to go out to sea.

In addition to the 59 chinook, 10 jacks (young adult males) were also taken from the Round Butte hatchery and released into the Metolius River, said Dobscha.

Fish enthusiasts are also pleased with this year’s results, though many hold out hope for better results in the coming years.

“Early spring chinook returns are surprisingly good compared to past years, although they’re still a long way away from targets,” said Yancy Lind, a local fish advocate and blogger.

“Extremely low water in the Crooked River will not allow many fish to get very far, but there are spawning areas in the lowest reaches, so I’m guardedly optimistic,” Lind added.

Lind points out that it is illegal to intentionally catch or keep spring chinook in the Upper Deschutes Basin (Deschutes, Metolius and Crooked rivers), but that poaching is a problem.

While some of the progress can be self-managed in the river, there are some factors that remain outside of the project’s control. This includes ocean conditions and streamflow levels.

“Streamflow affects smolt outmigration, survival and collection at the Selective Water Withdrawal,” said Becky Burchell, a fisheries biologist for Portland General Electric. “It also has an impact on adults as they migrate into the spawning tributaries.”

Around 50 of the returned chinook were given radio tags so biologists can track the movements of the fish as they meander through the upper basin, said Dobscha. All of the fish were also given green fish tags so that they can be easily identified if spotted or caught.

Biologists are not expecting many other types of fish to appear in the trap this time of year. In June it’s just spring chinook and bull trout. Sockeye salmon will begin arriving in July and summer steelhead will begin arriving in September.

Dobscha said ocean-going fish are getting some help from a recently constructed stress relief pond at the juvenile release site in the Lower Deschutes. The pond will allow fish additional time to rest and recover after handling before their evening release.

“The extra recovery time should improve survival during their ocean-going migration,” said Dobscha.

PGE is also conducting a smolt acclimation project, in which juvenile chinook and steelhead are held instream for several weeks prior to release, said Dobscha. The project is a joint effort among several entities, including the Oregon Department of Fish and Wildlife, the Confederated Tribes of Warm Springs and the Deschutes Land Trust.

Smolt acclimation helps fish imprint on the water’s unique scent. It also allows fish time to fully undergo “smoltification,” which is the physiological transformation that prepares fish for their ocean migration, said Dobscha.

“Acclimation in 2018, 2019 and 2020 greatly improved our collection of juveniles at the SWW,” Dobscha said, referring to the Selective Water Withdrawal. “This year, for the first time, 100% of juvenile fish were acclimated prior to release.”

Historically, there would have been more fish than are currently making their way to the dams, which were erected in the 1960s.

The Metolius River and Whychus Creek had documented spawning ground counts between 100 and 648 adults between 1951 and 1958, per state fish and wildlife biologists, said Burchell.

Despite the small number of returning fish, Burchell thinks there is plenty of room to increase the numbers, and the recent rise in numbers is promising.

“Our long-term goal is self-sustaining, harvestable runs of spring chinook, sockeye and summer steelhead in the Upper Deschutes Basin, including Whychus Creek, the Metolius and Crooked rivers,” said Burchell. “Our vision of success, which is based on the current habitat capacity of the upper basin, is 1,000 chinook returning each year.”

Burchell explains that the progress may take years. In the case of salmon, it could take three to five generations to establish baseline data on species performance. Chinook, she said, may remain in the ocean for two to three years before returning to their river spawning grounds.

“There’s a delay when we’re assessing the effectiveness of our management changes,” said Burchell. “It’s still relatively early on in a long-term effort.”

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