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Presentation Abstract

Forage fish are an important link between zooplankton and higher trophic levels, including marine mammals and economically valuable predatory fish. However, forage fish are often difficult to assess using traditional fishery-independent surveys, resulting in major data gaps for both commercially important and non-exploited species. In the Salish Sea, there are many data gaps about the distribution and regional importance of forage fish and other forage species (e.g., juvenile Gadiformes, euphausiids, crustacean larvae). We used the diet composition of adult Chinook salmon (Oncorhynchus tshawytscha), a generalist predator, to examine the spatial structure of forage assemblages in the Canadian Salish Sea from 2017 – 2021. Stomach contents analysis of >1700 stomachs revealed that the importance of forage species such as Pacific herring (Clupea pallasii), northern anchovy (Engraulis mordax), and Pacific sand lance (Ammodytes personatus) varied spatially and seasonally. Cluster analysis of Chinook salmon diet composition identified regions of the Salish Sea with distinct forage assemblages. The spatial structure identified here has implications for efforts to model and protect the food web supporting Chinook salmon, their marine mammal predators, and other economically and ecologically important species in the Salish Sea. This study demonstrates the utility of predator diet sampling to provide important data on forage species at spatial and temporal scales difficult to achieve using traditional fishery-independent surveys.

Session Title

Poster Session 2: The Salish Sea Food Web and Cycles of Life

Conference Track

SSE14: Posters

Conference Name

Salish Sea Ecosystem Conference (2022 : Online)

Document Type

Event

SSEC Identifier

SSE-posters-322

Start Date

26-4-2022 4:30 PM

End Date

26-4-2022 5:00 PM

Type of Presentation

Poster

Genre/Form

conference proceedings; presentations (communicative events); posters

Subjects – Topical (LCSH)

Forage fishes--Salish Sea (B.C. and Wash.); Chinook salmon--Food--Salish Sea (B.C. and Wash.); Predation (Biology)--Salish Sea (B.C. and Wash.); Food chains (Ecology)--Salish Sea (B.C. and Wash.)

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Type

Text

Language

English

Format

application/pdf

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Apr 26th, 4:30 PM Apr 26th, 5:00 PM

Adult Chinook salmon diets delineate regions with distinct forage assemblages in the Salish Sea

Forage fish are an important link between zooplankton and higher trophic levels, including marine mammals and economically valuable predatory fish. However, forage fish are often difficult to assess using traditional fishery-independent surveys, resulting in major data gaps for both commercially important and non-exploited species. In the Salish Sea, there are many data gaps about the distribution and regional importance of forage fish and other forage species (e.g., juvenile Gadiformes, euphausiids, crustacean larvae). We used the diet composition of adult Chinook salmon (Oncorhynchus tshawytscha), a generalist predator, to examine the spatial structure of forage assemblages in the Canadian Salish Sea from 2017 – 2021. Stomach contents analysis of >1700 stomachs revealed that the importance of forage species such as Pacific herring (Clupea pallasii), northern anchovy (Engraulis mordax), and Pacific sand lance (Ammodytes personatus) varied spatially and seasonally. Cluster analysis of Chinook salmon diet composition identified regions of the Salish Sea with distinct forage assemblages. The spatial structure identified here has implications for efforts to model and protect the food web supporting Chinook salmon, their marine mammal predators, and other economically and ecologically important species in the Salish Sea. This study demonstrates the utility of predator diet sampling to provide important data on forage species at spatial and temporal scales difficult to achieve using traditional fishery-independent surveys.