Presentation Abstract

The WDFW conducted a mid-water trawl/hydroacoustic survey at 18 index reaches across the southern Salish Sea (SSS) from Olympia to the Canadian Border, and into the eastern Strait of Juan de Fuca. Sampling occurred every other month from February 2016 to February 2017 to gather hydroacoustic data paired with pelagic trawls, vertical plankton tows, and CTD casts. Although 96 different species of fish and invertebrates were captured in the trawls, nine species made up 96% of the overall catch. Catch data demonstrated that Pacific Herring, a common prey of salmon, groundfish, seabirds, and marine mammals, were the most abundant forage fish in the surveyed area, making up 61% of total catch. In Hood Canal, where herring abundance has increased markedly over the last few years, herring made up 89% of total catch. Herring were the most abundant catch in all four sub-basins, although they exhibited large seasonal fluctuations and were a minor component of the catch in June, August, and December. Low herring catches in December were likely the result of fish moving into pre-spawn holding areas nearshore that were too shallow to trawl. Northern Anchovy were infrequently captured but sometimes represented a large percentage of the catch for an individual trawl, particularly in the southern basin in the late summer and early fall. Other notable forage species that made up significant portions of the catch included Pacific hake/whiting, shiner perch, and market squid. Overall, the study captured a “snapshot” of the pelagic species community in Puget Sound after an extended period of anomalously warm surface waters in the northeastern Pacific Ocean and will serve as a reference point for future studies. These data are presented with the hope of fostering future research on pelagic biotic communities and collaborations with researchers studying predators of forage fish throughout the Salish Sea.

Session Title

Transboundary Monitoring of Marine Birds and Mammals in the Salish Sea

Keywords

Forage fish, Acoustic trawl

Conference Track

SSE7: Monitoring: Species and Habitats

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE7-117

Start Date

4-4-2018 2:45 PM

End Date

4-4-2018 3:00 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 4th, 2:45 PM Apr 4th, 3:00 PM

Forage fish in the southern Salish Sea: results of the midwater acoustic trawl survey

The WDFW conducted a mid-water trawl/hydroacoustic survey at 18 index reaches across the southern Salish Sea (SSS) from Olympia to the Canadian Border, and into the eastern Strait of Juan de Fuca. Sampling occurred every other month from February 2016 to February 2017 to gather hydroacoustic data paired with pelagic trawls, vertical plankton tows, and CTD casts. Although 96 different species of fish and invertebrates were captured in the trawls, nine species made up 96% of the overall catch. Catch data demonstrated that Pacific Herring, a common prey of salmon, groundfish, seabirds, and marine mammals, were the most abundant forage fish in the surveyed area, making up 61% of total catch. In Hood Canal, where herring abundance has increased markedly over the last few years, herring made up 89% of total catch. Herring were the most abundant catch in all four sub-basins, although they exhibited large seasonal fluctuations and were a minor component of the catch in June, August, and December. Low herring catches in December were likely the result of fish moving into pre-spawn holding areas nearshore that were too shallow to trawl. Northern Anchovy were infrequently captured but sometimes represented a large percentage of the catch for an individual trawl, particularly in the southern basin in the late summer and early fall. Other notable forage species that made up significant portions of the catch included Pacific hake/whiting, shiner perch, and market squid. Overall, the study captured a “snapshot” of the pelagic species community in Puget Sound after an extended period of anomalously warm surface waters in the northeastern Pacific Ocean and will serve as a reference point for future studies. These data are presented with the hope of fostering future research on pelagic biotic communities and collaborations with researchers studying predators of forage fish throughout the Salish Sea.