Presentation Title

Qualitative approaches to evaluating potential causes of declines in marine survival of Pacific salmon

Session Title

The Salish Sea Marine Survival Project- Novel Approaches, Project Status and Key Findings

Conference Track

Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)

Contributing Repository

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

Type of Presentation

Oral

Abstract

Systematic declines in the returns of Chinook and coho salmon and steelhead in the Salish Sea and asynchronous patterns of marine survival compared to coastal stocks suggest that causes of declines can be explained by changes within the Salish Sea ecosystem. Scientists working with the Salish Sea Marine Survival Project are examining over 14 hypotheses that can explain declines and marine survival. Here, we describe retrospective approaches to evaluate hypotheses concerning anthropogenic and climate drivers. These approaches include both qualitative and quantitative approaches. Quantitative approaches via correlations of ecosystem indicators with patterns in marine survival can be challenging because not all potential drivers have associated indicators with long time series. Therefore, we describe qualitative approaches to examine how general patterns of salmon declines across all species conform with spatial patterns of environmental change. These qualitative approaches suggest that several hypotheses are insufficient for explaining spatial patterns of change for all salmon species, including positive trends in some pink and chum salmon stocks. We discuss the potential utility of combining these qualitative approaches with more quantitative analysis to improve our understanding of causes of declines in marine survival.

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.

Language

English

Format

application/pdf

Type

Text

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Qualitative approaches to evaluating potential causes of declines in marine survival of Pacific salmon

2016SSEC

Systematic declines in the returns of Chinook and coho salmon and steelhead in the Salish Sea and asynchronous patterns of marine survival compared to coastal stocks suggest that causes of declines can be explained by changes within the Salish Sea ecosystem. Scientists working with the Salish Sea Marine Survival Project are examining over 14 hypotheses that can explain declines and marine survival. Here, we describe retrospective approaches to evaluate hypotheses concerning anthropogenic and climate drivers. These approaches include both qualitative and quantitative approaches. Quantitative approaches via correlations of ecosystem indicators with patterns in marine survival can be challenging because not all potential drivers have associated indicators with long time series. Therefore, we describe qualitative approaches to examine how general patterns of salmon declines across all species conform with spatial patterns of environmental change. These qualitative approaches suggest that several hypotheses are insufficient for explaining spatial patterns of change for all salmon species, including positive trends in some pink and chum salmon stocks. We discuss the potential utility of combining these qualitative approaches with more quantitative analysis to improve our understanding of causes of declines in marine survival.