Tucannon River Spring Chinook Salmon Hatchery Evaluation Program: 2015 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 2015 to April 2016.

A total of 879 salmon were captured in the TFH trap in 2015 (271 natural adults, 14 natural jacks, 377 hatchery adults, and 217 hatchery jacks). Of these, 131 (101 natural, 30 hatchery) were collected and hauled to LFH for broodstock, 242 were held at LFH for adult outplanting, and the remaining fish were passed upstream. During 2015, two (1.5%) salmon collected for broodstock died prior to spawning.

Spawning of supplementation fish occurred once a week between 25 August and 22 September, with peak eggtake occurring on 15 September. A total of 280,519 eggs were collected from 55 natural and 20 hatchery-origin female Chinook. Egg mortality to eye-up was 2.7% (7,630 eggs) which left 272,889 live eggs. An additional 2.5% (6,755) loss of sac-fry left 266,134 BY 2015 fish for production.

Due to the drought conditions in 2015 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 232 fish were returned to the river in small groups (~15 pairs/group) and released at or above Cow Camp Bridge (rkm 72.9) at five different locations on 17 August and 24 August. No pre-spawn mortalities of outplanted fish were documented.

Evaluations personnel conducted pre-spawn mortality surveys in the Tucannon River between 15 May and 20 August during 2015. These surveys covered from Sheep Creek (rkm 84) to Bridge 10 (rkm 43). A cumulative total of 218 river kilometers were walked and 32 pre-spawn mortalities (15 hatchery, 13 natural, and 4 unknown origin) from fish passed upstream were recovered. Weekly spawning ground surveys were conducted from 26 August and were completed by 8 October 2015. A total of 191 redds and 188 carcasses (62 natural, 126 hatchery) were found. Carcass recovery rates were 10% for fish passed upstream and 31% for the adult outplant group. Survival of fish passed upstream was estimated to be only 32% during the time period fish were held at the hatchery. Based on redd counts, carcasses recovered, and broodstock collection, the estimated return to the river for 2015 was 1,777 spring Chinook (667 natural adults, 65 natural jacks and 855 hatchery-origin adults, 190 hatchery jacks).

Volitional release of the 2014 BY smolts began on 1 April and continued until 15 April, 2016 when the remaining fish were forced out. An estimated 221,099 BY14 smolts were released.

Evaluation staff operated a downstream migrant trap to provide juvenile outmigration estimates. During the 2014/2015 emigration, we estimated that 3,831 (2,722-5,667 95% C.I.) natural spring Chinook (BY 2013) smolts emigrated from the Tucannon River.

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