Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2004 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 2004 to April 2005.

Four hundred sixty-six fish were captured in the TFH trap in 2004 (309 natural adults, 2 natural jacks, 102 hatchery adults, and 53 hatchery jacks); 92 were collected and hauled to LFH for broodstock and the remaining fish were passed upstream.

During 2004, four 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 2004 at LFH occurred between August 24 and September 21, with peak eggtake on September 14. A total of 140,459 eggs were collected from 28 wild and 18 hatchery-origin fish. Egg mortality to eye-up was 4.5% (6,383 eggs), with an additional loss of 5,199 (3.9%) sac-fry. Total fry ponded for production in the rearing ponds was 128,877.

A total of 205 captive brood females were spawned from August 31 to October 5, 2004 producing 310,819 eggs. Egg mortality to eye-up was 49% leaving 158,902 live eggs. An additional 18,028 dead eggs/fry (11.3%) were picked at ponding leaving 140,874 fish for rearing.

WDFW staff conducted spawning ground surveys in the Tucannon River between September 1 and September 30, 2004. One hundred-sixteen redds and 78 carcasses were found above the adult trap and 44 redds and 43 carcasses were found below the trap. Based on redd counts, broodstock collection, and in-river pre-spawning mortalities, the estimated escapement for 2004 was 573 fish (400 wild adults, 0 wild jacks and 151 hatchery-origin adults, 22 hatchery jacks).

Length and weight samples were collected twice during the rearing cycle for 2003 brood year (BY) juveniles at TFH and Curl Lake Acclimation Pond. All 2003 BY juveniles were marked in October at LFH, transported to TFH, and transported again in February to Curl Lake for acclimation and volitional release during April.

Snorkel surveys were conducted during the summer of 2004 to determine the population of subyearling and yearling spring chinook in the Tucannon River. We estimated 40,900 subyearlings (BY 2003) and 1,205 yearlings (BY 2002) were present in the river. Evaluation staff also operated a downstream migrant trap. During the 2003/2004 emigration, we estimated that 60,530 (BY 2002) wild 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 four 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 173 hatchery-origin fish returned in 2004.