Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2005 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 was to compensate for the estimated annual loss of 1,152-spring Chinook (Tucannon River stock) caused by hydroelectric projects on the Snake River. The standard supplementation production goal is 132,000 fish for release as yearlings at 30 g/fish (15 fish per pound). The captive brood production goal is 150,000 yearlings at 30 g/fish. 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 April 2005 to April 2006.

Two hundred forty-five salmon were captured in the TFH trap in 2005 (125 natural adults, 6 natural jacks, 94 hatchery adults, and 20 hatchery jacks); 100 were collected and hauled to LFH for broodstock and the remaining fish were passed upstream. During 2005, five salmon that were collected for broodstock died. Prespawning mortality has been low since broodstock began being held at LFH in 1992, and is generally less than 10% each year.

Spawning of supplementation fish in 2005 at LFH occurred between August 23 and September 20, with peak eggtake on September 6. A total of 161,345 eggs were collected from 25 natural and 24 hatchery-origin fish. Egg mortality to eye-up was 3.2% (5,239 eggs), with an additional loss of 10,827 (6.9%) sac-fry. Total fry ponded for production in the rearing ponds was 145,279.

A total of 167 captive brood females were spawned from August 31 to October 11, 2005 producing 261,845 eggs. Egg mortality to eye-up was 60.4% leaving 103,812 live eggs. An additional 9,841 dead eggs/fry (9.5%) were picked at ponding leaving 93,971 fish for rearing.

WDFW staff conducted spawning ground surveys in the Tucannon River between August 31 and September 29, 2005. Forty-six redds and 22 carcasses were found above the adult trap and 56 redds and 29 carcasses were found below the trap. Based on redd counts, broodstock collection, and in-river pre-spawning mortalities, the estimated escapement for 2005 was 420 fish (286 natural adults, 3 natural jacks and 123 hatchery-origin adults, 8 hatchery jacks).

Snorkel surveys were conducted during the summer of 2005 to determine the population of subyearling and yearling spring Chinook in the Tucannon River. We estimated 30,809 subyearlings (BY 2004) and 586 yearlings (BY 2003) were present in the river. Evaluation staff also operated a downstream migrant trap. During the 2004/2005 emigration, we estimated that 23,003 (BY 2003) natural spring Chinook smolts emigrated from the Tucannon River.

Monitoring survival rate differences between natural and hatchery-reared salmon continues. Smolt-to-adult return rates (SAR) for natural salmon consistently average about five times higher than for hatchery salmon. However, hatchery salmon survive about 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 131 hatchery origin fish returned in 2005. Beginning with the 2006 brood year, the annual smolt goal will be increased from 132,000 to 225,000 to help offset for the higher mortality of hatchery-origin fish after they leave the hatchery. In conjunction with this we also plan to conduct an experiment to examine size at release as a possible means to improve SAR of hatchery fish.