Survival Patterns of Wild and Hatchery Coho Salmon in the Salish Sea
Presentation Abstract
Returns of coho salmon to the Salish Sea have declined over the past three decades. Studies in the Strait of Georgia have suggested that early marine environment is a critical survival bottleneck for multiple stocks whereas forecasting efforts in Puget Sound have highlighted the variable survival among stocks within a single year. A study which investigates spatial and temporal patterns in coho marine survival is needed to explain these observations. The objectives of the current study are to determine the spatial and temporal coherence in smolt-to-adult survival for coho salmon stocks, to compare hatchery and wild smolt-to-adult survival, to determine and compare early marine survival estimates among basins, and to evaluate the contributions of marine versus freshwater survival to overall productivity of wild coho salmon populations. Marine survival estimates were derived using coded-wire tag data and adult versus smolt count data from coho salmon stocks representative of regions both inside and outside the Salish Sea. A cluster analysis was used to identify the appropriate spatial scale to consider environmental factors driving marine survival. In addition, two approaches were used to determine the contribution of survival in the marine environment to overall returns of coho salmon. The first approach examines whether early marine survival, measured from Strait of Georgia and Puget Sound trawl surveys, explains variation in total marine survival of hatchery and wild coho salmon. The second approach examines whether variation in freshwater versus marine survival best explains the cohort sizes of wild coho salmon. The results of this work identify the appropriate spatial scale to develop ecosystem indicators of marine survival and describe the importance of the marine environment in driving coho salmon returns to the Salish Sea over the last three decades.
Session Title
Session S-06D: Marine Survival of Salmon and Steelhead: the Salish Sea Marine Survival Project
Conference Track
Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
1-5-2014 1:30 PM
End Date
1-5-2014 3:00 PM
Location
Room 611-612
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Coho salmon--Mortality--Salish Sea (B.C. and Wash.); Hatchery fishes--Mortality--Salish Sea (B.C. and Wash.); Coho salmon--Habitat--Salish Sea (B.C. and Wash.); Hatchery fishes--Habitat--Salish Sea (B.C. and Wash.)
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
Survival Patterns of Wild and Hatchery Coho Salmon in the Salish Sea
Room 611-612
Returns of coho salmon to the Salish Sea have declined over the past three decades. Studies in the Strait of Georgia have suggested that early marine environment is a critical survival bottleneck for multiple stocks whereas forecasting efforts in Puget Sound have highlighted the variable survival among stocks within a single year. A study which investigates spatial and temporal patterns in coho marine survival is needed to explain these observations. The objectives of the current study are to determine the spatial and temporal coherence in smolt-to-adult survival for coho salmon stocks, to compare hatchery and wild smolt-to-adult survival, to determine and compare early marine survival estimates among basins, and to evaluate the contributions of marine versus freshwater survival to overall productivity of wild coho salmon populations. Marine survival estimates were derived using coded-wire tag data and adult versus smolt count data from coho salmon stocks representative of regions both inside and outside the Salish Sea. A cluster analysis was used to identify the appropriate spatial scale to consider environmental factors driving marine survival. In addition, two approaches were used to determine the contribution of survival in the marine environment to overall returns of coho salmon. The first approach examines whether early marine survival, measured from Strait of Georgia and Puget Sound trawl surveys, explains variation in total marine survival of hatchery and wild coho salmon. The second approach examines whether variation in freshwater versus marine survival best explains the cohort sizes of wild coho salmon. The results of this work identify the appropriate spatial scale to develop ecosystem indicators of marine survival and describe the importance of the marine environment in driving coho salmon returns to the Salish Sea over the last three decades.
