Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2008 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-spring Chinook (Tucannon River stock) caused by hydroelectric projects on the Snake River. With co-manager agreement, the conventional supplementation production goal was increased in 2006 from 132,000 to 225,000 fish for release as yearlings at a size of 30 g/fish (15 fish per pound). 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 2008 to April 2009.

Five hundred salmon were captured in the TFH trap in 2008 (90 natural adults, 24 natural jacks, 118 hatchery adults, and 268 hatchery jacks). Of these, 134 (42 natural, 92 hatchery) were collected and hauled to LFH for broodstock and the remaining fish were passed upstream. During 2008, three salmon that were collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred between 2 September and 23 September, with a peak eggtake occurring on 16 September. A total of 193,324 eggs were collected from 17 natural and 43 hatchery-origin female Chinook. Egg mortality to eye-up was 2.6% (5,036 eggs), with an additional loss of 4,363 (2.3%) sac-fry. Total fry ponded for production in the rearing ponds was 183,925.

WDFW staff conducted spawning ground surveys in the Tucannon River between 27 August and 30 September, 2008. One hundred forty-one redds and 168 carcasses were found above the adult trap and 58 redds and 78 carcasses were found below the trap. Based on redd counts, broodstock collection, and in-river pre-spawning mortalities, the estimated escapement for 2008 was 1,191 spring Chinook (403 natural adults, 131 natural jacks and 185 hatchery-origin adults, 472 hatchery jacks).

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2007/2008 emigration, we estimated that 30,228 (BY 2006) natural spring Chinook smolts emigrated from the Tucannon River.

Smolt-to-adult return rates (SAR) for natural origin salmon average about five times higher than for hatchery origin salmon. However, hatchery salmon survive almost three times greater than natural salmon from parent to adult progeny. Due to the low SAR for hatchery fish, the mitigation goal of 1,152 salmon of Tucannon River stock was not achieved as only 657 hatcheryorigin fish returned in 2008. We are currently conducting an experiment to examine size at release as a possible means to improve SAR of hatchery origin spring Chinook.