Presentation Abstract

Nearshore marine habitats in the Salish Sea support populations of many fish species including migrating juvenile salmon, benthic sculpins, and rearing and spawning forage fish. The Strait of Juan de Fuca (SJF) is critical as a corridor between the Pacific Ocean and inland water bodies. Though known to utilize this area, the population dynamics of ecologically important forage fish are poorly understood. Over 9 years of monthly beach seine sampling (April – September) at 24 sites along 70 km of coastline in the SJF, we have observed high variability in fish catch across years, sites, and seasons. Annual catches ranged from 23,093 to 92,677 individual fish divided among 45 to 55 species. Forage fish were represented by 9 species and were numerically the dominant group, accounting for 87.8% of the catch from all sampling areas combined. Three forage fish species dominated, thus warranting in-depth investigation: Pacific Herring (Clupea pallasii), Pacific Sand Lance (Ammodytes hexapterus), and Surf Smelt (Hypomesus pretiosus). Influence of individual species varied, yet drove the fish assemblage structure. We explored effects of temporal and spatial variability on forage fish occurrence, abundance, and community composition using descriptive statistics and a Bayesian hierarchical modeling framework. Additionally, the removal of two large dams on the adjacent Elwha River, which released stored sediment into our sampling area, provided us an opportunity to examine forage fish response to a localized habitat perturbation. Spatially, individual species may avoid regions of high perturbation but dramatic variations in distribution and abundance of the greater forage fish community are temporally driven by larger scale changes. Management plans directed at forage fish should take into consideration how variation in abundance at regional scales and consistent population responses to large-scale environmental fluctuations may drive forage fish populations over time.

Session Title

Forage Fish Status, Spawning Beach Restoration and Monitoring, and Community Engagement in the Salish Sea

Keywords

Forage fish, Nearshore, Dam removal

Conference Track

SSE1: Habitat Restoration and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE1-90

Start Date

5-4-2018 1:45 PM

End Date

5-4-2018 2:00 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 5th, 1:45 PM Apr 5th, 2:00 PM

Spatio-temporal variation in the nearshore forage fish community in the Strait of Juan de Fuca

Nearshore marine habitats in the Salish Sea support populations of many fish species including migrating juvenile salmon, benthic sculpins, and rearing and spawning forage fish. The Strait of Juan de Fuca (SJF) is critical as a corridor between the Pacific Ocean and inland water bodies. Though known to utilize this area, the population dynamics of ecologically important forage fish are poorly understood. Over 9 years of monthly beach seine sampling (April – September) at 24 sites along 70 km of coastline in the SJF, we have observed high variability in fish catch across years, sites, and seasons. Annual catches ranged from 23,093 to 92,677 individual fish divided among 45 to 55 species. Forage fish were represented by 9 species and were numerically the dominant group, accounting for 87.8% of the catch from all sampling areas combined. Three forage fish species dominated, thus warranting in-depth investigation: Pacific Herring (Clupea pallasii), Pacific Sand Lance (Ammodytes hexapterus), and Surf Smelt (Hypomesus pretiosus). Influence of individual species varied, yet drove the fish assemblage structure. We explored effects of temporal and spatial variability on forage fish occurrence, abundance, and community composition using descriptive statistics and a Bayesian hierarchical modeling framework. Additionally, the removal of two large dams on the adjacent Elwha River, which released stored sediment into our sampling area, provided us an opportunity to examine forage fish response to a localized habitat perturbation. Spatially, individual species may avoid regions of high perturbation but dramatic variations in distribution and abundance of the greater forage fish community are temporally driven by larger scale changes. Management plans directed at forage fish should take into consideration how variation in abundance at regional scales and consistent population responses to large-scale environmental fluctuations may drive forage fish populations over time.