Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2018 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 2018 to April 2019.  
 
A total of 431 salmon were captured in the TFH trap in 2018 (62 natural adults, 11 natural jacks, 297 hatchery adults, and 61 hatchery jacks).  Of these, 160 adults (37 natural, 123 hatchery) were collected and hauled to LFH for broodstock, 38 adipose clipped strays were killed outright, 18 were passed upstream (15 natural, 3 hatchery), and the remaining fish (215) were held at LFH for adult outplanting.  During 2018, 20 (12.5%) salmon collected for broodstock died prior to spawning.   
 
Spawning of supplementation fish occurred once a week between 28 August and 18 September, with peak eggtake occurring on 11 September.  A total of 212,973 eggs were collected from 9 natural and 67 hatchery-origin female Chinook.  Egg mortality to eye-up was 3.1% (6,639 eggs) which left 206,334 live eggs.  An additional 0.95% (1,970) loss of sac-fry left 204,364 BY 2018 fish for production. 
 
Weekly spawning ground surveys were conducted from 21 August and were completed by 1 October 2018.   A total of 109 redds and 67 carcasses (9 natural, 58 hatchery) were found.  Seventy-seven redds (76% 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 2018 was 545 spring Chinook (80 natural adults, 0 natural jacks and 425 hatchery-origin adults, 40 hatchery jacks). 
 
Volitional release of the 2017 BY smolts began on 4 April and continued until 3 May, 2019 when the remaining fish were forced out.  An estimated 144,219 BY17 smolts were released. 
 
Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates.  During the 2017/2018 emigration, we estimated that 8,058 (4,618-16,014 95% C.I.) natural spring Chinook (BY 2016) 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 almost three times greater than natural salmon from parent to adult progeny over the length of the project.   
 
A study was conducted for three brood years (BY11-13) to determine if rearing full term at TFH would return more adults back to the Tucannon River versus the current protocol of egg incubation and early life rearing at LFH.  This study concluded with the final adult returns in 2018.  Results from PIT tag detections did not show a significant benefit in either survival or homing back to the Tucannon River by rearing fish at TFH instead of LFH.  Based on the findings, we will continue to use LFH for holding, spawning, and incubation and early life rearing of Tucannon River spring Chinook.