US Navy


Marine Species Monitoring

Characterizing the distribution of ESA-listed salmonids in Washington and Alaska

Introduction & Objectives

This project supports Pacific salmonid studies in the offshore waters of the existing Northwest Training Range Complex (NWTRC), offshore Naval Undersea Warfare Center Keyport Range Complex (together known as the Northwest Training and Testing (NWTT) Study Area), and the Gulf of Alaska Temporary Maritime Activities Area (GOA TMAA). The goal of this study is to use acoustic tagging technology to provide critical information on spatial and temporal distribution of salmonids to inform salmon management, U.S. Navy training activities, and Southern Resident Killer Whale (SRKW) conservation. 


Technical Approach

In May 2019, 107 acoustic receiver stations were deployed in a grid pattern along the coast of Washington State.  These will be retrieved, data downloaded, and redeployed until the end of the project. 

Salmonids including bull trout, Chinook salmon, and Coho salmon will be the target species for this project.  Data collected from caught fish will include measurements, fin clips for genetic analysis, and healthy fish of appropriate size will be tagged with either an acoustic pinger tag or a pop-up satellite tag. 

Analysis will include the use of oceanographic models to determine spatially explicit environmental conditions within the ocean, as well as the development of a specific analysis with Brad Hanson (NOAA Northwest Fisheries Science Center) to examine the degree to which tagged salmonids and piscivorous SRKW overlap through space and time.


Progress & Results

The Northwest Fisheries Science Center is currently conducting a study to characterize the occurrence of Chinook salmon within the Northwest Training and Testing area (NWTT). To date, acoustic transmitters have been surgically implanted into Chinook salmon along the coast of Washington (n = 142) from May to August 2019, near Kodiak, AK (n = 80) in October 2020, near Yakutat, AK (n = 32) in March 2021, and near Chignik, AK (n = 36) in August 2021. To detect acoustically tagged fish, acoustic receivers were deployed and serviced along the coast of Washington (n = 107) in a 4.5 km grid from 3 nm to 10 nm offshore within the Olympic Coast National Marine Sanctuary (OCNMS) in 2019 to 2020. Receiver orientation was changed to maximize the detection of Chinook salmon tagged in Alaska in July 2020 to two dense receiver lines (North Jetty line, n = 42, Long Beach line, n = 34, 1.25 km spacing) and one sparse receiver line (Willapa line, n = 8, 4 km spacing) perpendicular to the coast. Additionally, four receivers were deployed across the mouth of the Columbia River in July 2020. In September 2021 a line of receivers was deployed north of Grays harbor extending diagonally southward to Grays Canyon (Grays Canyon line, n = 10, 5 km spacing).

Stock origins analysis using genetics indicated that 11 evolutionary significant units (ESUs) of Chinook salmon were captured along the coast of Washington. This included three ESUs that are listed as Endangered Species Act (ESA) threatened: Lower Columbia River (55.8%), Willamette River spring (2.2%), and Snake River spring (0.6%). The origin of Chinook salmon captured in Kodiak, AK consisted of six ESUs. This included two ESUs that are listed as ESA threatened: Willamette River spring (6.3%) and Lower Columbia River (3.6%). The origin of fish captured in Yakutat, AK consisted of five ESUs. This included two ESUs that are listed as ESA threatened: Willamette River spring (16.7%) and Lower Columbia River (3.7%). To date, 13.8% of Kodiak and 15.6% of Yakutat acoustically tagged Chinook salmon have been detected. Salmon tagged in Chignik are expected to be returning to rivers starting in 2022. Once the detection histories are final, the migration route, estimated amount of time, and detection month for each ESU of detected Chinook salmon that occurred within the NWTT will be examined.

Publications: None