Abstract

Allometric scaling (where body size features as the independent variable) has been observed in many aspects of fish biology. Empirical studies have shown that individual and population rates of food consumption for single and multi-species datasets show positive allometry. However, the ratio of population consumption to biomass shows negative allometry when evaluated across species. In this paper, a theoretical explanation is proposed that predicts the magnitudes and signs of the allometric slopes for consumption and consumption/biomass within and among species. It is proposed that the ultimate cause of the allometries related to food consumption in fish lies in the physiology of growth. In the context of von Bertalanffy growth, the allometric slopes are caused by the constraints imposed on anabolism by the surfaces absorbing oxygen, by the volumetric relationship between linear body size and body mass, and by a dimensionless growth parameter. © CSIRO 2008.