Growth, size and abundance of juvenile coho salmon in the Strait of Georgia; 1999-2001 and 2012-2014
Presentation Abstract
Growth of juvenile coho salmon has been measured during the annual June/July DFO survey of the Strait of Georgia, 1999 – 2001 and 2012 - 2014. Growth was assessed by measuring plasma levels of the hormone insulin-like growth factor 1 (IGF1) from blood samples obtained during the survey. Two major patterns are apparent 1) IGF1 levels were higher 1999, 2012 – 2014 than found 2000 – 2001 and 2) for the period 2012 – 2014, growth was higher in northern regions of the Strait of Georgia as compared to southern regions. Sampling was limited to southern portions of the Strait of Georgia 1999 – 2001, precluding making a similar North to South comparison during that time period. Further analyses revealed several interesting relationships. There was a significant correlation between fork length and plasma IGF1 for coho salmon collected 1999, 2012 – 2014, suggesting that within these years larger fish had a greater ability to exploit food resources than smaller fish. Fish collected in 2000 – 2001 were relatively large but had low IGF1 values, suggesting that the overall prey field was reduced in those years (2000 – 2001). Finally, catch per unit effort (CPUE) was measured in each year for both the June/July survey and for the September survey. The ratio of September CPUE to June/July CPUE provides a simple assessment of change in abundance from June/July to September. Plasma IGF1 level measured in June/July was positively and significantly related to Sept/June CPUE, suggesting that higher growth rates during the early summer were associated with increased autumn abundance. Overall, these results suggest that there are significant inter-annual differences in juvenile coho salmon growth in the Strait of Georgia and that these differences in growth may be related to the resulting relative abundance of coho salmon in the autumn.
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
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
Type of Presentation
Oral
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--Monitoring--Georgia, Strait of (B.C. and Wash.); Coho salmon--Ecology--Georgia, Strait of (B.C. and Wash.); Fish stock assessment--Georgia, Strait of (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.); Georgia, Strait of (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
Growth, size and abundance of juvenile coho salmon in the Strait of Georgia; 1999-2001 and 2012-2014
2016SSEC
Growth of juvenile coho salmon has been measured during the annual June/July DFO survey of the Strait of Georgia, 1999 – 2001 and 2012 - 2014. Growth was assessed by measuring plasma levels of the hormone insulin-like growth factor 1 (IGF1) from blood samples obtained during the survey. Two major patterns are apparent 1) IGF1 levels were higher 1999, 2012 – 2014 than found 2000 – 2001 and 2) for the period 2012 – 2014, growth was higher in northern regions of the Strait of Georgia as compared to southern regions. Sampling was limited to southern portions of the Strait of Georgia 1999 – 2001, precluding making a similar North to South comparison during that time period. Further analyses revealed several interesting relationships. There was a significant correlation between fork length and plasma IGF1 for coho salmon collected 1999, 2012 – 2014, suggesting that within these years larger fish had a greater ability to exploit food resources than smaller fish. Fish collected in 2000 – 2001 were relatively large but had low IGF1 values, suggesting that the overall prey field was reduced in those years (2000 – 2001). Finally, catch per unit effort (CPUE) was measured in each year for both the June/July survey and for the September survey. The ratio of September CPUE to June/July CPUE provides a simple assessment of change in abundance from June/July to September. Plasma IGF1 level measured in June/July was positively and significantly related to Sept/June CPUE, suggesting that higher growth rates during the early summer were associated with increased autumn abundance. Overall, these results suggest that there are significant inter-annual differences in juvenile coho salmon growth in the Strait of Georgia and that these differences in growth may be related to the resulting relative abundance of coho salmon in the autumn.
