Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2012 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 5,760 (1,152 above the project area and 4,608 below the project area for harvest) Tucannon River spring Chinook 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. 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 2012 to April 2013.

A total of 541 salmon were captured in the TFH trap in 2012 (220 natural adults, 20 natural jacks, 232 hatchery adults, and 69 hatchery jacks). Of these, 170 (93 natural, 77 hatchery) were collected and hauled to LFH for broodstock and the remaining fish were passed upstream. During 2012, three of the salmon that were collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred between 28 August and 18 September, with peak eggtake occurring on 18 September. A total of 269,514 eggs were collected from 48 natural and 47 hatchery-origin female Chinook. Egg mortality to eye-up was 5.7% (15,262 eggs), with an additional loss of 8,219 (3.2%) sac-fry. Total fry ponded for 2012 BY production in the rearing ponds was 246,033.

WDFW staff conducted spawning ground surveys in the Tucannon River between 30 August and 4 October, 2012. Eighty-four redds and 43 carcasses were found above the adult trap and 85 redds and 79 carcasses were found below the trap. Based on redd counts, broodstock collection, and in-river pre-spawning mortalities, the estimated return to the river for 2012 was 1,239 spring Chinook (808 natural adults, 7 natural jacks and 416 hatchery-origin adults, 8 hatchery jacks).

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2011/2012 emigration, we estimated that 35,080 (30,063-41,026 95% C.I.) natural spring Chinook (BY 2010) smolts emigrated from the Tucannon River.

Smolt-to-adult return rates (SAR) for natural origin salmon were over five 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. Based on density-dependent effects we have observed, the mitigation goal may be higher than the habitat can support under current habitat conditions.