Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2019 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 Tucannon River spring Chinook for the period May 2019 to April 2020.

A total of 183 salmon were captured in the TFH trap in 2019 (37 natural adults, 2 natural jacks, 115 hatchery adults, and 29 hatchery jacks). Of these, 149 adults (36 natural, 113 hatchery) were collected for broodstock, one adipose clipped stray was killed outright, two males were passed upstream (1 natural, 1 hatchery), and 31 jacks (2 natural, 29 hatchery) were held at LFH for outplanting. During 2019, 64 (43.0%) salmon collected for broodstock died prior to spawning.
Spawning of supplementation fish occurred once a week between 3 September and 24 September, with peak eggtake occurring on 10 September. A total of 126,102 eggs were collected from 7 natural and 38 hatchery-origin female Chinook. Egg mortality to eye-up was 5.7% (7,213 eggs) which left 118,889 live eggs. An additional 0.6% (730) loss of sac-fry left 118,159 BY 2019 fish for production.

Weekly spawning ground surveys were conducted from 26 August and were completed by 9 October 2019. A total of 11 redds and 3 carcasses (1 natural, 2 hatchery) were found. Three redds (27% 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 2019 was 203 spring Chinook (43 natural adults, 2 natural jacks and 129 hatchery-origin adults, 29 hatchery jacks).
The 2018 BY smolts were direct stream released on 23-24 March just below Beaver/Watson Bridge (rkm 61.9) as the road to the acclimation pond was washed out due to flooding. An estimated 192,521 BY18 smolts were released.

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2018/2019 emigration, we estimated that 17,972 (13,302-25,871 95% C.I.) natural spring Chinook (BY 2017) smolts emigrated from the Tucannon River.
Smolt-to-adult return rates (SAR) for natural origin salmon are almost 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.