Mid-Hood Canal Juvenile Salmonid Evaluation: Duckabush River 2019

Category: Wild Salmon Population Monitoring

Published: July 2020

Pages: 39

Publication number: FPA 20-08

Author(s): Josh Weinheimer

Executive Summary

Juvenile salmonid monitoring in Hood Canal, Washington 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. Monitoring of Pacific salmon and steelhead on the Duckabush River, located in central Hood Canal and draining from the Olympic Mountains, began in 2007. This study measures the juvenile abundance and outmigration timing of Chinook salmon, chum salmon, pink salmon (even years only), coho salmon, and steelhead. We derive independent estimates for summer and fall chum salmon stocks in these watersheds via molecular genetic analysis. For those species with adult abundance surveys (chum, Chinook), we also estimate egg to migrant survival.

In 2019, a floating eight-foot screw trap was located at river mile 0.3 (0.48 rkm) and operated by WDFW from January 8 to June 23. The abundance of juvenile summer chum salmon was over 8 times larger than fall chum (Table 1). Egg-to-migrant survival was higher for summer than fall chum salmon. The median date of summer chum outmigration occurred 4 weeks earlier than the median of the fall chum outmigration.

TABLE 1.─Abundance, coefficient of variation (CV), egg-to-migrant survival, average fork length and median out-migration date for juvenile salmonids of natural origin leaving the Duckabush River, 2019.
Species Abundance Estimate Abundance CV Survival Median Migration Date Average Fork Length
Summer chum 379,002 6.21% 29.55% 3/17 --
Fall chum 42,919 17.68% 5.35% 4/14 --
Chinook 832 10.30% -- 3/28 42.6
Coho 1,525 24.79% -- 5/8 98.5
Steelhead 419 27.39% -- 5/8 162.9