Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2014 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 2014 to April 2015.

A total of 558 salmon were captured in the TFH trap in 2014 (314 natural adults, 29 natural jacks, 113 hatchery adults, and 102 hatchery jacks). Of these, 127 (86 natural, 41 hatchery) were collected and hauled to LFH for broodstock and the remaining fish were passed upstream. During 2014, one (0.8%) salmon collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred once a week between 2 September and 23 September, with peak eggtake occurring on 9 September. A total of 231,026 eggs were collected from 39 natural and 27 hatchery-origin female Chinook. Egg mortality to eye-up was 1.2% (2,697 eggs) which left 228,329 live eggs. An additional 0.9% (2,029) loss of sac-fry left 226,300 BY 2014 fish for production.

WDFW staff conducted pre-spawn mortality surveys in the Tucannon River between 13 June and 22 August during 2014. These surveys covered from Lady Bug Flat Campground (rkm 78) to Bridge 12 (rkm 47). A cumulative total of 119 river kilometers were walked but only three pre-spawn mortalities were recovered that were not part of a radio telemetry study. Weekly spawning ground surveys were conducted from 27 August and were completed by 3 October 2014. A total of 124 redds and 95 carcasses (69 natural, 26 hatchery) were found. Based on redd counts, carcasses recovered, broodstock collection, and in-river pre-spawning mortalities, the estimated return to the river for 2014 was 1,104 spring Chinook (861 natural adults, 41 natural jacks and 137 hatchery-origin adults, 65 hatchery jacks).

Volitional release of the 2013 BY smolts began on 27 March and continued until 16 April, 2015 when the remaining fish were forced out. A preliminary estimate of 174,013 BY13 LFH reared and 21,695 BY13 TFH reared fish were released based on detections at the Curl Lake passive integrated transponder (PIT) tag array. A final release number will be determined after previously undetected tags are detected along the outmigration corridor and will be provided in the 2015 annual report.

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2013/2014 emigration, we estimated that 12,886 (9,151-19,261 95% C.I.) natural spring Chinook (BY 2012) smolts emigrated from the Tucannon River.

Smolt-to-adult return rates (SAR) for natural origin salmon were over six 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.