Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2006 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. The conventional supplementation production goal was revised in 2006 to 225,000 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 2006 to April 2007.

One hundred thirty-nine salmon were captured in the TFH trap in 2006 (57 natural adults, 4 natural jacks, 70 hatchery adults, and 8 hatchery jacks); 89 were collected and hauled to LFH for broodstock and the remaining fish were passed upstream. During 2006, one salmon that was collected for broodstock died prior to spawning.

Spawning of supplementation fish in 2006 at LFH occurred between 29 August and 26 September, with peak eggtake on 12 September. A total of 123,629 eggs were collected from 18 natural and 27 hatchery-origin fish. Egg mortality to eye-up was 5.4% (6,685 eggs), with an additional loss of 4,594 (3.9%) sac-fry. Total fry ponded for production in the rearing ponds was 112,350.

A total of 86 captive brood females were spawned from 5 September to 3 October, 2006 producing 162,736 eggs. Egg mortality to eye-up was 38.9% leaving 99,420 live eggs. An additional 19,988 dead eggs/fry (20.1%) were picked at ponding leaving 79,432 fish for rearing.

WDFW staff conducted spawning ground surveys in the Tucannon River between 8 September and 25 September, 2006. Sixty-two redds and 25 carcasses were found above the adult trap and 39 redds and 28 carcasses were found below the trap. Based on redd counts, broodstock collection, and in-river pre-spawning mortalities, the estimated escapement for 2006 was 253 fish (133 natural adults, 7 natural jacks and 109 hatchery-origin adults, 4 hatchery jacks).

Snorkel surveys were conducted during the summer of 2006 to determine the population of subyearling and yearling spring Chinook in the Tucannon River. We estimated 21,162 subyearlings (BY 2005) and 1,012 yearlings (BY 2004) were present in the river. Evaluation staff also operated a downstream migrant trap. During the 2005/2006 emigration, we estimated that 21,057 (BY 2004) 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 113 hatcheryorigin fish returned in 2006. Beginning with the 2006 brood year, the annual smolt goal was increased from 132,000 to 225,000 to help offset 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.