Tucannon River Spring Chinook Salmon Captive Broodstock Program: 2006 Annual Report

This report summarizes the objectives, tasks, and accomplishments of the Tucannon River Spring Chinook Captive Broodstock Program during 2006. Results should be considered preliminary until published is a peer-reviewed journal.

The WDFW initiated a captive broodstock program in 1997. The captive broodstock program collected juvenile hatchery supplementation fish from five (1997-2001) brood years (BY) with additional fish collected from the 2002 BY. The overall goal of the Tucannon River captive broodstock program is for the short-term, and eventually long-term, rebuilding of the Tucannon River spring Chinook salmon population, with the hope that natural production will sustain itself in the future. The project goal is to rear captive salmon selected from the supplementation program to adults, spawn them, rear their progeny, and release approximately 150,000 smolts annually into the Tucannon River between 2003-2007. These smolts, in combination with the current hatchery supplementation program (132,000 smolts) and wild production, are expected to produce 600-700 returning adult spring Chinook to the Tucannon River each year from 2005-2010.

The 2006 eggtake from the 2001 brood year (Age 5) was 17,042 eggs from 8 ripe females. Egg survival was 54%. Mean fecundity based on the 8 fully spawned females was 2,130 eggs/female. The 2006 eggtake from the 2002 brood year (Age 4) was 145,694 eggs from 78 ripe females. Egg survival was 62%. Mean fecundity based on the 78 fully spawned fish was 1,868 eggs/female. The total 2006 eggtake from the captive brood program was 162,736 eggs. A total of 63,316 dead eggs (38.9%) were removed with 99,420 live eggs remaining for the program. An additional 19,988 dead eggs/fry (20.1%) were picked at ponding leaving 79,432 fish for rearing.

Only two captive brood progeny adult returns were recovered during 2006. Survival to adult returns has been poor for this program to date.

Microsatellite DNA analysis to date provides evidence that the captive broodstock program has been an effective method of preserving overall genetic variation in Tucannon River spring Chinook while providing additional smolts for release.

During April 2007, WDFW volitionally released 90,056 BY 2005 captive broodstock progeny smolts from Curl Lake Acclimation Pond into the Tucannon River. These fish were marked only with a CWT in order to differentiate them from the supplementation fish (CWT/Right Red VIE/No Finclip). One thousand captive brood progeny smolts were PIT tagged to compare their outmigration with smolts from the supplementation program (1,002 tagged). Monitoring their survival and adult returns, along with future natural production levels, will be used to determine the success or failure of this captive broodstock program.