Lyons Ferry Hatchery Evaluation Fall Chinook Salmon Annual Report: 2006

This report summarizes activities by the Washington Department of Fish and Wildlife’s (WDFW) Lower Snake River Hatchery Evaluation Program for the period 16 April 2006 through 15 April 2007. We have also included the Statistical Analysis of 2006 Lower Granite Dam Fall Chinook Run Reconstruction report funded by the Pacific Salmon Commission’s Southern boundary Restoration and Enhancement Fund in order to make it more widely available.

In 2006, WDFW collected 3,679 fish at Lyons Ferry Hatchery (LFH) and Lower Granite Dam (LGR) for broodstock, monitoring and evaluation of our hatchery releases, and to estimate the run size to LGR. This was the fourth year that natural origin fish were integrated into our broodstock. Of the total number of fish contributing to production, 81.1% were Lyons Ferry hatchery origin, 12.2% were natural origin, 5.1% were out-of-basin stray hatchery fish based on scale readings, and 1.6% were of unknown origin.

A total of 2,819,004 green eggs were taken at Lyons Ferry Hatchery, well below the full production goals listed in the 2005-2007 United States v. Oregon Management Agreement. Survival from green to eye-up was 96.8% with an estimated 1.1% additional loss to ponding.

WDFW released brood year 2005 (BY05) sub-yearlings directly from LFH (202,211 fish), two releases (200,820 and 211,508 fish) into the Snake River near Couse Creek Boat Launch (Rkm 253.7), and two releases (200,432 and 208,733 fish) directly into the Grande Ronde River near the mouth of Cougar Creek. The first Couse Creek release was part of an ongoing direct vs. acclimated study (released from the Captain John acclimation site). An accidental fry (BY05) release of 71,000 fry at 181 fpp occurred on 4 April at LFH. The LFH also released 503,160 yearling fall Chinook (BY05) into the Snake River on site from 2-6 April 2007. Releases of fish into the Snake Basin from 2000 through 2007 are provided.

We surveyed the Tucannon River by foot, covering 91% of the historical spawning area of fall Chinook. We estimated 449 fall Chinook and 11 summer Chinook escaped to the Tucannon River, producing an estimated 153 redds. The return to the Tucannon River was estimated to be 45% inbasin hatchery fish, 14% out-of-basin hatchery fish, 30% natural origin fish, 9% unknown origin fish (hatchery or wild), and 2% summer Chinook.

Smolt-to-adult return estimates for broodyears 1999 through 2005 are presented for fish released by WDFW. Yearlings continue to provide a survival advantage over subyearlings although it is highly variable year to year. We present data showing a survival advantage of onstation subyearlings when compared to direct releases into the Snake River near Couse Creek and the Grande Ronde River.

We adjusted harvest estimates of CWT tagged fish by fishery, sample detection type, and tag loss to fully reflect total take of non-tagged, non-clipped, as well as adipose clipped, and CWT tagged fall Chinook. Analysis was done solely on recoveries of fall Chinook released by WDFW and does not include recoveries of LSRCP fish from the Nez Perce Tribe (NPT), fish released from NPT Hatchery, or fish released from Idaho Power Company programs.

Of the WDFW releases, we estimate that 2,844 fall Chinook were taken in fisheries downstream of the Snake River in 2006. By location, fishers in the Columbia River harvested 38% of the total number harvested and fishers in British Columbia harvested 37%. By fishery, the British Columbia Troll fishery intercepted 28% of all fish harvested. This is the first time we have attempted to expand the CWT data in this manner and although it is preliminary, it shows the importance of doing so to fully reflect and understand the harvest component for mitigation.

Outside of the Snake River basin, 25 of Washington’s fall Chinook were intercepted at hatcheries or racks and 40 were recovered on spawning grounds. We estimate that 4,827 LFH/Snake River hatchery origin fall Chinook released by WDFW returned to the Snake River.