Intensively Monitored Watersheds: 2009 Fish Population Studies in the Hood Canal Stream Complex

The Hood Canal Intensively Monitored Watersheds study includes four adjacent streams (Little Anderson, Big Beef, Seabeck, and Stavis creeks) that flow into the east side of Hood Canal. Coho salmon are the focal species for this study, although information on steelhead and chum are also collected. Objectives of fish population studies on the Hood Canal IMW streams are to

(1) estimate abundance of coho parr and parr-to-smolt survival in all four creeks,

(2) estimate juvenile production of coho and steelhead smolts in all four creeks,

(3) compare timing of juvenile outmigration among watersheds,

(4) determine escapement of coho and chum into Big Beef Creek,

(5) describe spawning distribution and timing of coho salmon in all four creeks, and

(6) estimate harvest rate and marine survival of Big Beef Creek coho.

Abundance and survival of coho parr were estimated using a mark-recapture approach. Parr were marked in selected stream reaches during surveys conducted in late July and early August. Marked coho were recaptured in downstream traps the following spring. For the 2007 brood year, parr abundance was highest in Big Beef Creek (N = 224,097, CV = 5.24%) and lowest in Seabeck (N = 7,541, CV = 10.15%) and Little Anderson (N = 9,123, CV = 12.02%) creeks. Coho parr abundance in Stavis Creek was estimated to be 29,727 (CV = 9.83%). Parr-to-smolt survival of the 2007 brood year was 19.26% in Big Beef Creek as compared to 11.58% in Little Anderson, 7.99% in Seabeck, and 11.33% in Stavis Creek.

Abundance of coho and steelhead smolts was estimated from fish captured in downstream traps operated between April and June. Downstream fan traps were operated on Big Beef Creek and fence weirs were operated on Little Anderson, Seabeck, and Stavis creeks. In 2009, coho smolt production was highest in Big Beef Creek (N = 45,398). Coho production was 1,101 smolts in Little Anderson Creek, 626 smolts in Seabeck, and 3,474 smolts in Stavis Creek. Steelhead smolt production was 1,005 in Big Beef Creek, 2 in Little Anderson, 21 in Seabeck, and 17 in Stavis Creek.

A total of 971 adult coho and 36 jack coho returned to the Big Beef Creek weir in 2009. Hatchery-origin coho represented 3.8% of the adult return and 8.3% of the jack return. Survivalto- return rate for jack coho was 0.08%. Marine survival of age-3 adult coho was 13.40%. Harvest rate of Big Beef Creek coho was 71.0% of the total run. Estimates of marine survival and harvest should be considered a lower bound due to unreported catch from some fisheries at the time of this report. Chum escapement to Big Beef Creek in 2009 included 132 summer chum and 370 fall chum. Seven adult steelhead (6 males, 1 female) were observed returning to Big Beef Creek in 2009, although this is likely an underestimate of escapement as a trap outage occurred in early January.