Event Title

Salish Sea Coho Salmon Declines – The Problem is not in Freshwater

Presentation Abstract

The Salish Sea Marine Survival Program is based on the assumption that factors operating in the marine waters of the Salish Sea are responsible for declining numbers of adult salmon returning to freshwater. In order to evaluate this assumption, one needs to consider the possibility that conditions outside the Salish Sea may be responsible, whether these exist in marine waters outside the Salish Sea, or in freshwater. Zimmerman et al. (Mar Coastal Fish 7:116–134, 2015) demonstrated that coho salmon smolt survivals within the Salish Sea declined during the period of study (1977-2010 ocean entry years), while those of reference populations outside the Salish Sea did not. The current study considers the possibility that declining adult returns may be the result of factors operating in freshwater. Data assembled for naturally spawning populations on both sides of the Can/US border were examined. Freshwater (spawner to smolt) survivals were highly variable but showed little evidence of consistent declines over time. Although the conservation of naturally spawning salmon requires the maintenance of suitable freshwater ecosystems, there is little evidence that declining coho salmon returns to the Salish Sea are the result of factors operating exclusively in fresh water.

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.)

Document Type

Event

Location

2016SSEC

Type of Presentation

Oral

Contributing Repository

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

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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Salish Sea Coho Salmon Declines – The Problem is not in Freshwater

2016SSEC

The Salish Sea Marine Survival Program is based on the assumption that factors operating in the marine waters of the Salish Sea are responsible for declining numbers of adult salmon returning to freshwater. In order to evaluate this assumption, one needs to consider the possibility that conditions outside the Salish Sea may be responsible, whether these exist in marine waters outside the Salish Sea, or in freshwater. Zimmerman et al. (Mar Coastal Fish 7:116–134, 2015) demonstrated that coho salmon smolt survivals within the Salish Sea declined during the period of study (1977-2010 ocean entry years), while those of reference populations outside the Salish Sea did not. The current study considers the possibility that declining adult returns may be the result of factors operating in freshwater. Data assembled for naturally spawning populations on both sides of the Can/US border were examined. Freshwater (spawner to smolt) survivals were highly variable but showed little evidence of consistent declines over time. Although the conservation of naturally spawning salmon requires the maintenance of suitable freshwater ecosystems, there is little evidence that declining coho salmon returns to the Salish Sea are the result of factors operating exclusively in fresh water.