Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2017 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 5,760 (1,152 above the project area and 4,608 below the project area for harvest) Tucannon River spring Chinook caused by hydroelectric projects on the Snake River. With co-manager agreement, the hatchery supplementation production goal was increased in 2006 from 132,000 to 225,000 fish for release as yearlings. 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 2017 to April 2018.

A total of 263 salmon were captured in the TFH trap in 2017 (17 natural adults, 9 natural jacks, 101 hatchery adults, and 136 hatchery jacks). Of these, 111 (18 natural, 93 hatchery) were collected and hauled to LFH for broodstock, fifteen adipose clipped strays were killed outright, and the remaining fish (137), primarily jacks, were held at LFH for potential broodstock supplementation or killed outright for jack management. No fish were passed upstream of the TFH adult trap. During 2017, fourteen (12.6%) salmon collected for broodstock died prior to spawning, a marked increase from previous years.

Spawning of supplementation fish occurred once a week between 29 August and 26 September, with peak eggtake occurring on 12 September. A total of 181,664 eggs were collected from 8 natural and 52 hatchery-origin female Chinook. Egg mortality to eye-up was 3.9% (7,140 eggs) which left 174,524 live eggs. An additional 4.5% (7,934) loss of sac-fry left 166,590 BY 2017 fish for production.

Weekly spawning ground surveys were conducted from 30 August and were completed by 5 October 2017. A total of 70 redds and 41 carcasses (8 natural, 33 hatchery) were found. Twenty-nine redds (41% of the total) were counted above the adult trap even though fish were not passed upstream. Based on redd counts, carcasses recovered, and broodstock collection, the estimated return to the river for 2017 was 512 spring Chinook (60 natural adults, 9 natural jacks and 284 hatchery-origin adults, 159 hatchery jacks).

Volitional release of the 2016 BY smolts began on 9 April and continued until 27 April, 2018 when the remaining fish were forced out. An estimated 209,031 BY16 smolts were released.

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2016/2017 emigration, we estimated that 14,305 (10,325-22,431 95% C.I.) natural spring Chinook (BY 2015) smolts emigrated from the Tucannon River.