Fish/Shellfish Research and Management
Date Published: July 2012
Number of Pages: 71
Publication Number: FPA 12-04
Author(s): Josh Weinheimer and Mara Zimmerman
Juvenile salmonid monitoring in central Hood Canal, Washington began in 2002 on the Hamma Hamma River and in 2007 on the Duckabush River. This work has been a collaborative project between the Washington Department of Fish and Wildlife (WDFW), Long Live the Kings (LLTK), and the Northwest Fisheries Science Center’s (NWFSC) Manchester Research Station. This report describes the juvenile abundance, egg-to-migrant survival, and outmigration timing of chum and Chinook salmon in 2011. In addition, we derived independent estimates for summer and fall chum salmon stocks in these watersheds. Coho salmon and steelhead smolt catches were too few to expand to an abundance estimate. As expected, no pink salmon fry were captured during the 2011 outmigration period (even-year returns are not observed in these watersheds).
A floating five-foot screw trap was located at river mile 0.3 (0.48 rkm) and operated by WDFW and LLTK from January 10 to July 26, 2011. The juvenile production of summer chum salmon was ten times larger than fall chum (Table 1). Egg-to-migrant survival for summer and fall chum salmon ranged between 5.1% and 6.8%. The peak of the summer chum outmigration occurred 4 weeks earlier than the peak of the fall chum outmigration. Low numbers of juvenile Chinook were counted despite the fact that no adults were observed spawning in 2010. Based on juvenile abundance, we estimate that the observed production resulted from less than 5 female Chinook spawners.
Hamma Hamma River
A floating eight-foot screw trap was located at river mile 0.5 (0.8 rkm) and operated by LLTK from January 27 to June 26, 2011. Juvenile production of fall chum salmon was nearly 4 times larger than the summer chum salmon (Table 1). Egg-to-migrant survival averaged 14.1% for the fall stock and 6.1% for the summer stock. Juvenile production of Chinook salmon was estimated to be 10,664 sub-yearlings with an egg-to-migrant survival of 6.4%.