This project will quantitatively evaluate the relative reproductive success of naturally spawning hatchery and natural origin spring Chinook salmon in the Wenatchee River. Hatcheries are one of the main tools that have been used to mitigate for salmon losses caused by the construction and operation of the Columbia River hydropower system. In addition to harvest augmentation, hatcheries have recently been used in attempts to protect stocks from extinction and to enhance natural production (supplementation). Surprisingly, little is known about how much the investment in hatcheries benefits or harms natural production. We propose to take advantage of recent technological advances in genetics to empirically monitor the reproductive success of hatchery and natural spring Chinook salmon using a DNA-based pedigree approach. Specifically, we will (1) directly measure the relative reproductive success of hatchery and natural-origin Chinook salmon in both natural and hatchery settings, (2) determine the degree to which any differences in reproductive success between hatchery and natural Chinook salmon can be explained by measurable biological characteristics such as run timing or size, and (3) estimate the relative fitness of hatchery-lineage Chinook salmon after they have experienced an entire generation in the natural environment. Sponsors have requested that the project last until 2024 in order to evaluate the influence hatchery-lineage on relative fitness after fish spend a single generation in the natural environment, and, evaluate the overall effectiveness of hatchery reform actions on the population.

In 2019, work under this contract transitioned to trapping and collecting DNA samples and biological data from only natural-origin potential spawners at Tumwater Dam and progeny from the 2017 spawners at the lower Wenatchee smolt trap. Final DNA tissue collections from progeny of 2017 spawners were completed at the lower Wenatchee smolt trap in 2020. DNA tissue collections from natural-origin adult fish continued at Tumwater Dam in 2020 and will proceed through 2023 to ensure progeny from 2017 spawners are sampled as returning adults.

This project is a collaboration between NOAA-Fisheries (Northwest Fisheries Science Center) and the Washington Department of Fish and Wildlife. The combined budget total will be in alignment with the approved budget for the project. Results and progress will be reported on jointly. Specifically, a joint authored, single annual report will be generated for the contract period and will be delivered under this contract (CR-345017).

This project is an extension of the Chinook salmon supplementation and monitoring program in the Wenatchee River operated by WDFW and funded by Chelan County PUD.