Event Title

Possible mechanisms of small-scale regional variability of juvenile coho salmon growth in the Strait of Georgia

Presentation Abstract

Growth during early marine residence is correlated to survival to adulthood, thus the growth of juvenile coho in the Strait of Georgia is important for overall survival. The physiologic growth potential of a given individual is correlated to temperature and food quality and quantity. In the summers of 2012, 2013, 2014, and 2015 juvenile coho salmon were collected within diverse regions within the Strait of Georgia to compare regional growth rates and potential influences on differences in growth such as diet contents and water temperature. Sampling ranged from the Gulf Islands in the south to the Discovery Islands in the north. Growth was assessed via plasma concentration of insulin-like growth factor-1, or IGF-1. IGF-1 is correlated to instantaneous (within 3-7 days) growth in juvenile fishes. There was significant variation in growth between the northern Strait of Georgia and southern Strait of Georgia in 2012 and 2014 (p<0.05). While growth did vary in 2013 and 2015 among regions, the difference observed in 2012 and 2014 between the south and north was absent. The mean percent (by visual volume) of each of the four most common stomach contents (young-of-the-year herring, larval fish, larval crab, and hyperiid amphipod) was calculated for coho salmon in each region. The proportion stomach content for each prey item for each region was regressed with regional mean IGF-1 concentration within a year. Significant positive correlations between regional IGF-1 concentration and regional percent of young-of-the-year herring and larval fish in diets was found across all years (p>0.05). Non-significant negative relationships were observed between IGF-1 concentration and crab larvae (megalops and zoea) and hyperiid amphipod. Additionally, there was no significant correlation between regional water column temperature at 5 meters and regional IGF-1 among years or regions within a year. These results provide a direct field based correlation between positive growth and increased larval fish consumption (most importantly young-of-the-year herring). Further emphasizing higher caloric quality diet contents as an important component in early marine growth of juvenile coho salmon.

Session Title

Posters: Species & Food Webs

Conference Track

SSE18: Posters

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE18-118

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

Possible mechanisms of small-scale regional variability of juvenile coho salmon growth in the Strait of Georgia

Growth during early marine residence is correlated to survival to adulthood, thus the growth of juvenile coho in the Strait of Georgia is important for overall survival. The physiologic growth potential of a given individual is correlated to temperature and food quality and quantity. In the summers of 2012, 2013, 2014, and 2015 juvenile coho salmon were collected within diverse regions within the Strait of Georgia to compare regional growth rates and potential influences on differences in growth such as diet contents and water temperature. Sampling ranged from the Gulf Islands in the south to the Discovery Islands in the north. Growth was assessed via plasma concentration of insulin-like growth factor-1, or IGF-1. IGF-1 is correlated to instantaneous (within 3-7 days) growth in juvenile fishes. There was significant variation in growth between the northern Strait of Georgia and southern Strait of Georgia in 2012 and 2014 (p<0.05). While growth did vary in 2013 and 2015 among regions, the difference observed in 2012 and 2014 between the south and north was absent. The mean percent (by visual volume) of each of the four most common stomach contents (young-of-the-year herring, larval fish, larval crab, and hyperiid amphipod) was calculated for coho salmon in each region. The proportion stomach content for each prey item for each region was regressed with regional mean IGF-1 concentration within a year. Significant positive correlations between regional IGF-1 concentration and regional percent of young-of-the-year herring and larval fish in diets was found across all years (p>0.05). Non-significant negative relationships were observed between IGF-1 concentration and crab larvae (megalops and zoea) and hyperiid amphipod. Additionally, there was no significant correlation between regional water column temperature at 5 meters and regional IGF-1 among years or regions within a year. These results provide a direct field based correlation between positive growth and increased larval fish consumption (most importantly young-of-the-year herring). Further emphasizing higher caloric quality diet contents as an important component in early marine growth of juvenile coho salmon.