Laboratory growth and food consumption data for two size classes of brown trout Salmo trutta that experienced three distinct feeding regimes at two temperatures were used to evaluate the abilities of two bioenergetics models to predict fish growth. Accuracy of cumulative consumption predictions was also tested for one of the models. Model errors for predicting relative growth rate of individual fish were regressed on observed mean daily consumption rate to assess whether consumption-dependent prediction error commonly observed in bioenergetics models for other fish species was exhibited by the two brown trout bioenergetics models. Both models yielded unbiased estimates of brown trout growth that were within 1-12% of observed values across the range of fish sizes, water temperatures, and ration levels tested. Bonferroni joint 95% confidence intervals for the slopes and intercepts of regressions of predicted final weight on observed final weight included a slope of 1 and a y-intercept of 0 for both models. No significant inter-model differences in percent error for predicting final weight of fish in feeding trials were observed. Predicted cumulative consumption values were within 8-15% of corresponding observed values. Neither model exhibited significant consumption-dependent error for predicting brown trout growth, in contrast to results of several previous laboratory evaluations of bioenergetics models for other fish species. Absence of consumption-dependent error in the two brown trout models may be due to incorporation of feeding rate-dependence of egestion and excretion in these models and that egestion and excretion parameters were not borrowed from other species. Results of this evaluation corroborate the utility of these bioenergetics models for predicting growth and consumption for brown trout under the range of fish sizes, water temperatures, and ration levels tested.
Transactions of the American Fisheries Society