Summer- and fall-run chinook were once abundant in the Yakima River Basin, but the runs were decimated as a result of historical land and water development and fisheries management practices. By 1970, the summer-run component was extirpated and the fall-run is maintained by hatchery production using out-of-basin broodstock.

The Yakama Nation began stocking out-of-basin hatchery-reared juvenile fall chinook in the Yakima River at Prosser in the early 1980s; local production of fall chinook began at the Prosser Hatchery in 1997. Currently, fall chinook returning to the Yakima River are a combination of hatchery-origin upriver bright (URB) stock imported as eyed eggs from Little White Salmon Hatchery and progeny of local broodstock captured in the vicinity of Prosser Hatchery. All fall chinook are reared and released as subyearling smolts from the Prosser Hatchery or acclimation sites in the lower Naches or middle Yakima rivers.

The summer-run and URB-stock fall chinook are part of the Upper Columbia River summer/fall chinook Evolutionarily Significant Unit (ESU). In 1998, the National Marine Fisheries Service (NMFS) determined that this ESU did not warrant listing under the Endangered Species Act, but in 2009, the Columbia River Hatchery Scientific Review Group (HSRG) designated the Yakima River fall chinook population as a Contributing population[1].

Targeted Population:

Yakima Spring Chinook