BREMERTON — About 400 adult chinook salmon received a free bus ride up the Skokomish River in Washington this year, as biologists perfected a plan to boost dwindling runs of wild chinook.
The fish recruited into the pilot project showed up at the George Adams fish hatchery on Purdy Creek with an intact adipose fin. Presence of this fin suggests that these fish started their lives in the river, not the hatchery. Somehow they decided to head up into the hatchery instead of staying in the river.
The chinook, up to 3 feet long, splashed wildly this week, as biologists pulled them out of a concrete pond at the hatchery, clipped a piece of fin for genetic testing and then attached a colorful tag for identification. The fish were placed in tubes and then dropped into a tanker truck for transport to the tributary streams of LeBar and Brown creeks.
Structural problems and flow conditions in the much-abused South Fork of the Skokomish River keep many adult salmon from reaching viable spawning areas, said Cindy Gray, a biologist for the Skokomish Tribe. It makes sense to physically move these fish onto the spawning grounds, where their offspring are likely to survive and begin their journey to the ocean.
As in many salmon supplementation projects, the goal on the Skokomish River is to increase the number of wild spawners until they reach a self-sustaining population. This year’s pilot project is testing the logistics of moving the fish and monitoring their behavior.
The George Adams hatchery pumps out large numbers of chinook, which contribute to sport and commercial fisheries in the region. Genetic tests have shown, however, that chinook spawning in the river are not only lower in number, they are virtually identical to those coming back to the hatchery.
Because hatchery operations clip off the adipose fins before chinook are released as fry, the presence or absence of a fin can help biologists sort the hatchery salmon from wild ones.
“All we’re doing with this,” Gray said, “is moving the fish up into the river, where they can spawn naturally. We’re giving them a lift past the blockages.”
If the project continues, however, ongoing genetic testing will help the researchers determine which fish are reproductively successful and whether natural selection produces a new breed of chinook. Beginning next spring, a special trap will capture the tiny out-migrating smolts to measure the success of the pilot project.
Dave Herrera, fisheries policy manager for the Skokomish Tribe, said the plan was reviewed by the National Marine Fisheries Service for compliance with the Endangered Species Act.
Other studies are under way to improve the structure and flow capabilities of the river, and someday the summer-fall population of chinook may thrive without help, Herrera said. Years ago, the river was known for its early-arriving spring chinook, and a new stock may be introduced into the North Fork of the Skokomish to rebuild that run.
This year’s pilot program involved moving fish once a week for four weeks. Wednesday was the final day, and 25 fish were taken 15 miles upstream and released. The fish quickly dispersed, searching for spawning gravel both upstream and downstream of the release site.
Biologists will walk the streams this fall to assess where the fish have gone, the location of redds (gravel nests) along the streams as well as the timing of actual spawning.
The project is a joint effort of the Skokomish Tribe and Washington Department of Fish and Wildlife, which operates the George Adams Hatchery.
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