Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2016 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 2016 to April 2017.

A total of 595 salmon were captured in the TFH trap in 2016 (116 natural adults, 11 natural jacks, 299 hatchery adults, and 169 hatchery jacks). Of these, 126 (55 natural, 71 hatchery) were collected and hauled to LFH for broodstock, 330 were held at LFH for adult outplanting, and the remaining fish were passed upstream. During 2016, three (2.4%) salmon collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred once a week between 30 August and 20 September, with peak eggtake occurring on 6 September. A total of 245,174 eggs were collected from 31 natural and 41 hatchery-origin female Chinook. Egg mortality to eye-up was 4.5% (10,999 eggs) which left 234,175 live eggs. An additional 1.7% (4,069) loss of sac-fry left 230,106 BY 2016 fish for production.

Due to the relatively low run size in 2016 and the recent high pre-spawn mortality rates for Tucannon River spring Chinook, fish managers decided to hold a portion of the returning adults at LFH and then returning those fish to the upper stream reaches near the beginning of spawning. A total of 296 fish were returned to the river in small groups (~15 pairs/group) and released between Curl Lake (rkm 65.6) and Lady Bug Flat Campground (rkm 77.8) at nine different locations on 22 August and 23 August. Four pre-spawn mortalities of outplanted fish were recovered.

Evaluations personnel conducted pre-spawn mortality surveys in the Tucannon River between 23 June and 19 August during 2016, after which regular weekly spawning ground surveys commenced. These surveys covered from Camp Wooten (rkm 68) to Bridge 12 (rkm 47). Weekly spawning ground surveys were conducted from 26 August and were completed by 30 September 2016. A total of 154 redds and 113 carcasses (39 natural, 74 hatchery) were found. Based on redd counts, carcasses recovered, and broodstock collection, the estimated return to the river for 2016 was 752 spring Chinook (215 natural adults, 8 natural jacks and 397 hatcheryorigin adults, 132 hatchery jacks).

Volitional release of the 2015 BY smolts began on 4 April and continued until 21 April, 2017 when the remaining fish were forced out. An estimated 199,686 BY15 smolts were released.

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2015/2016 emigration, we estimated that 6,604 (5,674-7,696 95% C.I.) natural spring Chinook (BY 2014) smolts emigrated from the Tucannon River.

Smolt-to-adult return rates (SAR) for natural origin salmon were almost eight 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.

Preliminary data does not show a significant benefit in either survival or homing back to the Tucannon River by rearing fish at TFH instead of LFH. Unless future data shows a different result, we will continue to use LFH for holding, spawning, and incubation and early life rearing of Tucannon River spring Chinook.