The Importance of Activity in Bioenergetics Models Applied to Actively Foraging Fishes

We used the Kitchell et al. (J. Fish. Res. Board Can. 34: 1922–1935) bioenergetics model and field derived estimates of growth and consumption rates to estimate the quantity of energy allocated to activity by 28 combinations of yellow perch (Perca flavescens) age class and population. Activity costs among populations ranged from 0 to 40% of the perch bioenergetics budget. We further evaluated the influence of activity rates on the food consumption estimates predicted by the Kitchell et al. model and the model proposed by Kerr (Can. J. Fish. Aquat. Sci. 39: 371–379). As suggested by Kerr, activity costs increased as food consumption increased. However, we found no significant relationship between predicted and observed food consumption estimates for either model. The magnitude of, and the among-population variance in, the quantity of energy allocated to activity is consistent with our hypothesis that this component of the bioenergetics budget of fishes has the potential to contribute meaningfully to the explanation of inter-population differences in perch growth and, by extension, to the variance in growth of other actively foraging fish species.