Bioenergetic Factors to Consider in Evaluating and Predicting the Effects of Global Climate Change on Fishes

A number of studies have sought to predict the impact of global climate change (GCC) on fishes using critical thermal maxima (CTM) or bioenergetic approaches.  Not unexpectedly, rising temperatures typically mean loss of habitat for many, particularly cold and coolwater species.  Use of CTM as an end point ignores ontogenetic shifts in thermal tolerance and also paints a more optimistic picture that would be estimated using a bioenergetics approach.  Even the bioenergetics approach fails to consider individual variation in thermal performance that appears to exist in fish, yet has not been quanitified with respect to population-level consequences in light of GCC.  Here examples with brook trout Salvelinus fontinalis show alternate outcomes to brook trout populations under CTM, average bioenergetics, and individual bioenergetics scenarios that suggest GCC impacts may be substantially greater than predicted with CTM criteria.