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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13383

Spatial and interannual variability of juvenile coho salmon growth in the Strait of Georgia (2012 – 2015)

*Meredith L. Journey, Chrys Neville, Graham Young, Marc Trudel, Brian R. Beckman

*Corresponding author:

ABSTRACT: We conducted a four-year (2012-2015) study of regional growth of juvenile coho salmon in the Strait of Georgia. Size (fork length) and growth (insulin-like growth factor 1 (IGF-1) concentration) varied both regionally and inter-annually. Additionally, we found a positive relationship between IGF-1 concentration and fork length that varied between years, with slopes and y-intercepts higher in 2012 and 2014 (even years), respectively, as compared to 2013 and 2015 (odd years). An ordinal increase of IGF-1 concentration from the south to north in 2012 and 2014 was coupled with an increase in the prevalence of juvenile herring and juvenile fish in the diet. Across all years, there was a positive relationship between regional mean IGF-1 concentration and regional mean percent of juvenile herring in the diet. Our study demonstrates relatively small-scale spatial heterogeneity in juvenile coho salmon growth that in part, was attributed to regional variation in diet. These findings also demonstrate the utility of short-term growth measures (such as IGF-1) for assessing relatively small-scale spatial and temporal differences in growth.