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 Study Area (GOA). 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 Chinook and coho salmon, steelhead, and bull trout are the target species for this project.  Data collected from caught fish includes 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 includes 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 Pacific salmon within the Northwest Training and Testing area (NWTT). In 2019, acoustic transmitters (tags) were surgically implanted into 142 Chinook salmon, 35 coho salmon, 41 steelhead kelts, and 17 bull trout caught in coastal marine waters of Washington State. In addition, 14 steelhead kelts in the Willapa River were tagged with pop-up satellite tags. In Alaskan marine waters, from 2020-2022, 296 subadult and adult Chinook salmon were acoustically tagged with transmitters near Chignik, Kodiak, Yakutat, Craig, and Sitka.

To detect these tagged fish, 107 acoustic receivers were deployed along the Washington coast. This receiver array was repositioned each year to address specific objectives.

In 2019, 107 acoustic receiver stations were deployed in a grid pattern to improve the understanding of Washington coast salmonid habitat occupancy for salmonids that were captured and tagged in Washington and Alaskan waters. Additionally, in 2019 a Slocum Glider integrated with two acoustic receivers was deployed along the Washington coast to supplement the array detections.

In 2020, receivers were serviced and redeployed in three receiver lines designed to detect Chinook salmon returning to the Columbia River from their tagged location in Kodiak, AK and Yakutat, AK.

In 2021, the orientation of the 107 acoustic receiver stations were revised to maximize the detection of Chinook salmon tagged in Alaska in July 2020. The array was configured into four receiver lines deployed perpendicular to the coast from immediately north of Grays Harbor south to the Columbia River.

In 2022, more than 100 receivers and selected Soundtraps were deployed in two lines (one due west of Cape Flattery and a second line to the southwest of Pacific Beach, Washington), and in a grid pattern from Grays Harbor south to the Columbia River. This orientation was created to help determine juvenile salmon outmigration occurrence in the Columbia River plume and return migration patterns of adult Chinook tagged in Alaska.

The tagged salmonid data will be analyzed to investigate salmon migration patterns and marine habitat use as they migrate between Pacific Northwest (PNW) and Alaska waters. These data will then be compared to data collected from Soundtraps off the Washington coast. These Soundtraps passively listen for the detection of vocalizing whales, including SRKW. As salmonids are the principal prey for SRKW, the distribution patterns of salmonids will be analyzed in conjunction with the Soundtrap data to estimate likely distribution patterns of SRKW and their primary food source in the PNW.