Spring Chinook Salmon Hatchery Mitigation Evaluation for S.E. Washington: 2023 Annual Report

Lyons Ferry Hatchery (LFH) and Tucannon Fish Hatchery (TFH) were built/modified under the Lower Snake River Fish and Wildlife Compensation Plan. One objective of the Plan is to compensate for the estimated annual loss of 1,152 Tucannon River spring Chinook caused by hydroelectric projects on the Snake River. This report summarizes activities of the Washington Department of Fish and Wildlife Lower Snake River Hatchery Evaluation Program for the Tucannon and Touchet River spring Chinook hatchery programs for the period May 2023 to April 2024.

A total of 108 salmon were captured in the TFH trap in 2023 (33 natural adults, 0 natural jacks, 37 hatchery adults, and 38 hatchery jacks). Of these, 93 fish (33 natural adults, 0 natural jacks, 29 hatchery adults, and 31 hatchery jacks) were collected for broodstock and 12 adipose clipped strays were killed outright. During 2023, two (2.2%) salmon collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred once a week between 29 August and 19 September, with peak eggtake occurring on 5 September. A total of 122,670 eggs were collected from 26 natural and 17 hatchery-origin female Chinook. Egg mortality to eye-up was 5.0% (6,151 eggs) which left 116,519 live eggs. An additional 0.9% (1,003) loss of sac-fry left 115,516 BY 2023 fish for production.

Weekly spawning ground surveys began 28 August and were completed by 29 September 2023. A total of 13 redds and 7 carcasses (2 natural, 5 hatchery) were found. No redds were counted above the adult trap. Based on redd counts, carcasses recovered, and broodstock collection, the estimated return to the river for 2023 was 138 spring Chinook (42 natural adults, 0 natural jacks and 58 hatchery-origin adults, 38 hatchery jacks).

A total of 235,734 BY22 smolts were released during 2024 (200,141 released at TFH on 9-10 April, 17,005 were released at the mouth of the Tucannon River on 17 April, and 18,588 were transported by barge on 18 April).

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2022/2023 emigration, we estimated that 3,356 (95% C.I. 2,750-4,219) natural spring Chinook (BY 2021) smolts emigrated from 30 September 2022 to 30 June 2023 from the Tucannon River.

Smolt-to-adult return rates (SAR) for natural origin salmon are nine times higher on average (based on geometric means) than hatchery origin salmon. However, hatchery salmon survive two times greater than natural salmon from parent to adult progeny over the length of the project. Managers are currently implementing an alternative release strategy evaluation (releases from TFH, releases at the Tucannon River mouth, and a barge transport release). Discussions continue about releasing a portion of the program at Kalama Falls Fish Hatchery in an attempt to increase hatchery fish survival and preserve this stock.

From the Touchet spring Chinook program we released 113,982 BY22 smolts during 18-21 March 2024. In 2023, we estimate that 44 fish (44 adults, 0 jacks) returned over McNary Dam.

Hatchery returns from both the Tucannon and Touchet hatchery programs will be used to measure contribution towards the LSRCP spring Chinook hatchery mitigation goal (1,152) for SE Washington. For the 2023 return year, both programs combined contributed to 9% of the SE Washington mitigation goal.