Presentation Abstract

Removal of two dams on the Elwha River, Washington from 2011 to 2014 has begun to restore natural sediment processes to the coastal environment near the river mouth. Since 2006, we have been collecting data on shallow subtidal (nearshore) fish communities near the Elwha River and at reference sites in the Strait of Juan de Fuca to assess fish response to sediment changes resulting from dam removal. Juvenile salmon (Chinook, coho, pink and chum salmon) migrate through this region, which also supports ecologically important forage fish and endemic benthic fauna. Beach seine samples collected annually from April through September from over 20 sites span pre-removal, high impact (during dam removal), and post-removal years. Annual catches included 23,093 to 92,677 individuals from 45-55 species. Trends in species richness and abundance were variable over this time period. Forage fish dominated our catches followed by salmonids. In this analysis we explored patterns of juvenile salmonid abundance in relation to dam removal, environmental variables, site characteristics (including community composition), and year/season using a Bayesian hierarchical modeling framework and multivariate analyses. Chinook salmon show a tenfold variation in abundance over the years examined. Catches of Chinook and coho salmon were dominated by locally released hatchery fish with high variability between sampling sites. Throughout this region we have seen a marked decrease in coho salmon catches in recent years. Understanding what biotic and abiotic factors contribute most to this variability in salmon abundance and distribution may help tailor future dam removal processes or reframe management decisions.

Session Title

Posters: Habitat Restoration & Protection

Keywords

Salmon, Forage fish, Elwha Dam removal

Conference Track

SSE18: Posters

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE18-69

Start Date

5-4-2018 11:30 AM

End Date

5-4-2018 1:30 PM

Type of Presentation

Poster

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, 11:30 AM Apr 5th, 1:30 PM

Salmonid distribution and abundance in the context of Elwha River dam removals

Removal of two dams on the Elwha River, Washington from 2011 to 2014 has begun to restore natural sediment processes to the coastal environment near the river mouth. Since 2006, we have been collecting data on shallow subtidal (nearshore) fish communities near the Elwha River and at reference sites in the Strait of Juan de Fuca to assess fish response to sediment changes resulting from dam removal. Juvenile salmon (Chinook, coho, pink and chum salmon) migrate through this region, which also supports ecologically important forage fish and endemic benthic fauna. Beach seine samples collected annually from April through September from over 20 sites span pre-removal, high impact (during dam removal), and post-removal years. Annual catches included 23,093 to 92,677 individuals from 45-55 species. Trends in species richness and abundance were variable over this time period. Forage fish dominated our catches followed by salmonids. In this analysis we explored patterns of juvenile salmonid abundance in relation to dam removal, environmental variables, site characteristics (including community composition), and year/season using a Bayesian hierarchical modeling framework and multivariate analyses. Chinook salmon show a tenfold variation in abundance over the years examined. Catches of Chinook and coho salmon were dominated by locally released hatchery fish with high variability between sampling sites. Throughout this region we have seen a marked decrease in coho salmon catches in recent years. Understanding what biotic and abiotic factors contribute most to this variability in salmon abundance and distribution may help tailor future dam removal processes or reframe management decisions.