Spring Chinook Salmon Hatchery Mitigation Evaluation for S.E. Washington: 2022 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 2022 to April 2023.

A total of 224 salmon were captured in the TFH trap in 2022 (172 natural adults, 18 natural jacks, 25 hatchery adults, and 13 hatchery jacks). Of these, 153 fish (143 natural adults, 1 natural jack, and 9 hatchery adults) were collected for broodstock and 15 adipose clipped strays were killed outright. During 2022, one (0.7%) salmon collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred once a week between 30 August and 20 September, with peak eggtake occurring on 6 September. A total of 282,614 eggs were collected from 81 natural and 4 hatchery-origin female Chinook. Egg mortality to eye-up was 1.8% (5,170 eggs) which left 277,444 live eggs. An additional 8.4% (23,314) loss of sac-fry left 254,130 BY 2022 fish for production.

Weekly spawning ground surveys began 31 August and were completed by 30 September 2022. A total of 41 redds and 33 carcasses (17 natural, 16 hatchery) were found. Twenty-three redds (56% of the total) were counted above the adult trap. Based on redd counts, carcasses recovered, and broodstock collection, the estimated return to the river for 2022 was 273 spring Chinook (211 natural adults, 9 natural jacks and 43 hatchery-origin adults, 10 hatchery jacks).

A total of 120,047 BY21 smolts were released during 2023 (79,465 released at TFH on 11 April, 20,288 were released at the mouth of the Tucannon River on 19 April, and 20,294 were transported by barge on 20 April).

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2021/2022 emigration, we estimated that 1,889 (95% C.I. 1,114-3,313) natural spring Chinook (BY 2020) smolts emigrated from 30 September 2021 to 22 July 2022 from the Tucannon River.

Smolt-to-adult return rates (SAR) for natural origin salmon are over eight times higher on average (based on geometric means) than hatchery origin salmon. However, hatchery salmon survive three 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 or re-initiating a captive broodstock program in an attempt to increase hatchery fish survival and preserve this stock.

From the Touchet spring Chinook program we released 252,995 BY21 smolts during 20-23 March 2023. Since this is the first annual reporting for the Touchet program, information on broodstock sources, 2020-2022 releases, and their outmigration performance are provided for historical context. In 2022, we estimate that 250 fish (248 adults, 2 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 2022 return year, both programs combined contributed to 22% of the SE Washington mitigation goal.