Variation in Temperature-Dependent Growth Rates in Juvenile Chinook Salmon: The Need for Population-Specific Bioenergetics

Growth of juvenile salmonids is a critical variable affecting survival and recruitment to successive life history stages, essentially affecting the strength of subsequent cohorts.  Consumption and temperature are key variables affecting growth for fishes in general.  Temperature dictates the metabolic efficiency of prey conversion to production, and is thus a primary variable affecting growth.  However, temperature optima and thresholds are variable for Pacific salmon populations.  Yet many researchers using bioenergetic approaches to understand growth use temperature-dependent equations and coefficients for Chinook Salmon published in Steward & Ibarra (1991) which is based on adults from Lake Michigan, and uses coefficients from other salmonid species.  To address this problem we are using an approach using several lines of evidence to better understand relationships between temperature and key bioenergetic functions.  We focus this effort on juvenile Chinook Salmon used in the San Joaquin River Restoration Program, which seeks to restore the southern-most run in North America.  Our approach includes growth simulation using coefficients from different literature sources, simulations with inSTREAM and bioenergetics models, and two hatchery data sets.  The main objectives are to generate population and habitat specific bioenergetics algorithms and encourage a broader use of population-specific relationships of temperature and growth rate.