Streaming Media
Presentation Abstract
Previous research has shown that juvenile Chinook outmigrants prey preferentially on young-of-year Pacific herring and Pacific sand lance as they transit the San Juan Islands. The relative abundance of these two forage fishes and their proportional representation in the neritic diet of juvenile Chinook have varied since 2009 in ways that suggest that they respond to changing marine conditions in different ways, including relying seasonally on different zooplankton prey. In 2020 and 2021, co-occurring forage fishes (herring, sand lance, Pacific surf smelt, Northern Anchovy) and zooplankton were collected from a Lopez Island bay where juvenile Puget Sound Chinook annually congregate. Comparisons of forage fish gut contents with the prey field show that herring and sand lance compete seasonally for large calanoid copepods; while co-occurring smelt make greater use of benthic resources such as nemertean worms. Sand lance alone make seasonal use of the autumn flush of large disc diatoms. Prey competition by Northern Anchovy is documented for the first time in the Salish Sea. Results suggest that while herring, sand lance and anchovy compete to some extent for high-value prey, they differ in their use of secondary resources, and consequently in the way their diet will be affected by climate change.
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-92
Start Date
26-4-2022 4:30 PM
End Date
26-4-2022 5:00 PM
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
Foraging strategy, prey preferences and limited competition among forage fishes in the San Juan Islands; implications for Chinook recovery
Previous research has shown that juvenile Chinook outmigrants prey preferentially on young-of-year Pacific herring and Pacific sand lance as they transit the San Juan Islands. The relative abundance of these two forage fishes and their proportional representation in the neritic diet of juvenile Chinook have varied since 2009 in ways that suggest that they respond to changing marine conditions in different ways, including relying seasonally on different zooplankton prey. In 2020 and 2021, co-occurring forage fishes (herring, sand lance, Pacific surf smelt, Northern Anchovy) and zooplankton were collected from a Lopez Island bay where juvenile Puget Sound Chinook annually congregate. Comparisons of forage fish gut contents with the prey field show that herring and sand lance compete seasonally for large calanoid copepods; while co-occurring smelt make greater use of benthic resources such as nemertean worms. Sand lance alone make seasonal use of the autumn flush of large disc diatoms. Prey competition by Northern Anchovy is documented for the first time in the Salish Sea. Results suggest that while herring, sand lance and anchovy compete to some extent for high-value prey, they differ in their use of secondary resources, and consequently in the way their diet will be affected by climate change.
