Mid-Hood Canal Juvenile Salmonid Evaluation: Duckabush River 2014

The Duckabush is a high-gradient watershed that drains into the western side of Hood Canal, Washington. Peak flow events in this watershed occur twice each year, during rain-on-snow events in the winter months and snow melt in the spring months. The Duckabush system originates in the Olympic Mountains within the Olympic National Park. Human development is minimal with the exception of light logging activity in the upper watershed and residential homes and dikes in the lower part of the river and estuary.

The Duckabush river supports a diverse salmonid community, including Chinook salmon (Oncorhynchus tshawytscha), chum salmon (O. keta), pink salmon (O. gorbuscha), coho salmon (O. kisutch), and steelhead trout (Oncorhynchus mykiss). Three of the salmonid species are federally protected under the Endangered Species Act (ESA). Chinook salmon are part of the Puget Sound Chinook Evolutionary Significant Unit (ESU), summer chum populations are part of the Hood Canal summer chum ESU, and steelhead are part of the Puget Sound steelhead Distinct Population Segment (DPS), as delineated by the National Marine Fisheries Service (NMFS).

Chinook salmon in the Duckabush are part of the Puget Sound Chinook ESU listed as threatened in 1999 by NMFS under the Endangered Species Act (NOAA 1999b). Hood Canal has two genetically distinct Chinook salmon populations, one is the Skokomish River stock and the other is the Mid-Hood Canal stock that is composed of the Hamma Hamma, Duckabush, and Dosewallips subpopulations (Committee 2007). Recovery goals for the Mid-Hood Canal population range between 1,325 and 5,200 adults, depending on the rate of freshwater productivity (adults per spawner). Specifically, the Duckabush sub-population recovery goals are between 325 and 1,200 adults. Both the Skokomish and Mid-Hood Canal stocks will need to achieve low risk status for Puget Sound ESU recovery.

Summer chum salmon in the Duckabush river are part of the Hood Canal summer chum ESU listed as threatened in 1999 by NMFS (NOAA 1999a). The Hood Canal summer chum ESU was historically composed of 16 independent populations (Ames et al. 2000). Summer chum are distinguished from fall and winter chum based on spawn timing and genetic differentiation (Ames et al. 2000; Crawford and Rumsey 2011). Historically, summer chum stocks in Hood Canal returned in the tens of thousands. By 1980, these returns plummeted to fewer than 5,000 adults and 8 of the 16 stocks were considered extinct. To promote conservation, the WDFW and Point No Point Treaty (PNPT) Tribes developed the Summer Chum Salmon Conservation Initiative which called for reductions in harvest of Hood Canal summer chum and hatchery supplementation in order to rebuild stocks to harvestable levels (Ames et al. 2000). The initiative also called for increased monitoring and improvements to freshwater habitat conditions. The Duckabush summer chum stock is one of the eight extant stocks within Hood Canal. The recovery goals for Duckabush Summer Chum is an abundance of 3,290 adults with an escapement of 2,060 adults over a 12 year period and have at least an average recruits per spawner of 1.6 over the 8 most recent brood years.

Steelhead in the Duckabush are part of the West Hood Canal Winter-Run Steelhead demographically independent population (PSSTRT 2011). The West Hood Canal Winter-Run Steelhead DIP combines winter steelhead from the Hamma Hamma, Duckabush and Dosewallips rivers, and Quilcene River/Dabob Bay. Historic escapement data is lacking for this DIP, but based on recent stream surveys, the population most likely consists of only a few hundred fish. In response to the low estimates, the Hood Canal Steelhead Project was initiated in 2007 by NOAA Fisheries. The goals of the project were to access the benefits of conservation hatchery programs, provide guidance to fisheries managers about steelhead hatchery practices and recovery policies, and attempt to recover three Hood Canal steelhead populations (Duckabush, Dewatto and South Fork Skokomish). The project is monitoring 8 streams within Hood Canal that are divided between supplemented and control streams. The Duckabush is one of three supplemented streams and receives hatchery smolts and adults that are the progeny of excavated natural origin steelhead redds from the Duckabush.

NMFS evaluates the status species listed under the ESA using four viable salmon population (VSP) parameters: abundance, productivity, spatial distribution and diversity (McElhany et al. 2000). A statewide monitoring framework, termed "Fish-In Fish-Out", was developed by the Governor's Forum on Monitoring Salmon Recovery and Watershed Health and recommended the coupling of juvenile and adult monitoring for representative populations within each ESU (Crawford 2007). Guidelines for monitoring data needed to assess recovery status were recently published by the National Marine Fisheries Service (Crawford and Rumsey 2011). At the time of listing, little to no information was available on juvenile abundance or freshwater productivity of Chinook, summer chum, or steelhead in Hood Canal. Freshwater productivity (egg-to-migrant survival or smolts per spawner) is an important factor that contributes to population persistence and resilience (McElhany et al. 2000). Without information on juvenile migrants, managers are limited in their ability to assess the contributions of freshwater versus marine environment towards species recovery.

In response to these information needs, a juvenile monitoring study was initiated on the Duckabush River in 2007. The long-term goal for this study is to understand the factors that govern the freshwater productivity and marine survival of salmonid populations in the Duckabush River.   The combination of juvenile and spawner abundance allows for brood-specific survival to be partitioned between the freshwater and marine environment.  Long-term combination of juvenile and adult abundance data over a range of spawner abundances and flow regimes will provide a measure of freshwater capacity as well as current ranges of freshwater and marine survival.

This report summarizes results from the Duckabush River during the 2014 outmigration. In 2014, the primary objective of this study was to estimate the abundance, productivity and life history diversity of Chinook, Coho, pink, chum and steelhead in the Duckabush River. We conclude by discussing patterns of freshwater survival observed across the 2010-2014 time series.