Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2013 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 2013 to April 2014.

A total of 539 salmon were captured in the TFH trap in 2013 (226 natural adults, 45 natural jacks, 154 hatchery adults, and 114 hatchery jacks). Of these, 158 (98 natural, 60 hatchery) were collected and hauled to LFH for broodstock and the remaining fish were passed upstream. During 2013, seven (4.4%) of the salmon that were collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred between 27 August and 24 September, with peak eggtake occurring on 10 September. A total of 275,188 eggs were collected from 48 natural and 30 hatchery-origin female Chinook. Egg mortality to eye-up was 3.0% (8,357 eggs) which left 266,831 live eggs. A total of 30,000 of those eggs were transferred to TFH for full term rearing. An additional 1.2% (2,772) loss of sac-fry at LFH and 1.4% (429) loss of sac-fry at TFH left 263,630 BY 2013 fish for production (234,059 LFH, 29,571 TFH).

WDFW staff conducted spawning ground surveys in the Tucannon River between 28 August and 8 October, 2013. A total of 64 redds and 33 carcasses (23 natural, 10 hatchery) were found. While 374 (118 females) spring Chinook salmon were passed above the adult trap, only twentyfive redds and 11 carcasses were found upstream of the trap. The reason for the high pre-spawn mortality in 2013 is unknown and radio tagged fish will be tracked in 2014 to look for a potential cause. Based on redd counts, broodstock collection, and in-river pre-spawning mortalities, the estimated return to the river for 2013 was 1,117 spring Chinook (661 natural adults, 91 natural jacks and 297 hatchery-origin adults, 68 hatchery jacks).

Volitional release of the 2012 BY smolts began on 11 April and continued until 23 April, 2014 when the remaining fish were forced out. Based on detections at the Curl Lake PIT tag array, it was estimated that 129,952 BY12 LFH reared and 16,609 BY12 TFH reared fish were released.

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2012/2013 emigration, we estimated that 23,376 (20,848-27,056 95% C.I.) natural spring Chinook (BY 2011) 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.