The Relationship between Growth and Consumption: Comparisons across Fish Populations

Abstract

Comparisons of growth rates and consumption rates among fish populations are not straightforward and are difficult to interpret in the absence of other information about the populations. Differences in temperature regimes, reproductive timing, activity cost, prey availability, caloric densities of predator and prey, and allometric effects of body size on metabolism are factors that can alter the direct effect of consumption rate on growth rate, We developed a method to elucidate relations between growth and consumption by correcting for allometric weight effects. Bioenergetics model simulations showed that when growth rate is regressed against consumption rate (on either an absolute or a relative basis), the relationship is confounded by the allometric effects of differences in body weight among the populations being compared. Regressing growth rates on the difference between actual and maintenance consumption rate corrects for most of the allometric effects. That regression can be used to determine whether growth rate differences are best explained by consumption (in conjunction with weight allometries), temperature regime differences, variable activity costs, or other factors. Bioenergetics models can be used to evaluate the relative importance of factors limiting growth for fish populations.