Food and space revisited: The role of drift-feeding theory in predicting the distribution, growth, and abundance of stream salmonids

Abstract

In this paper we review drift-feeding models for stream salmonids. We assess their historical development and current state, and we propose areas for future research. Drift-feeding models serve as the critical input for energetics-based habitat selection and habitat quality models, which have recently begun to see widespread use for predicting salmonid distribution, growth and abundance. We use a bibliometric approach to find drift-feeding model publications, especially those citing three landmark papers that began the quantification of drift feeding by stream fish (Fausch 1984; Hughes and Dill 1990; Hill and Grossman 1993). Subsequent drift-feeding models have largely been built upon these models. Research effort has focused on model development and applications but model testing has been neglected. To date, the only rigorous test of a drift-feeding model (Hughes et al. 2003) identified several limitations and violations of model assumptions. The most important limitation was that prey capture- and gross energy intake rates were overestimated by a factor of two, due largely to poor predictions of prey detection probabilities. Consequences of error in drift-feeding models, and consequently in the habitat selection/quality models that employ them, are greater for applications aimed at predicting growth and abundance than they are for predicting distribution. Research effort on a broad front is needed to advance both drift-feeding models and habitat selection/quality models, including: further development of drift-foraging theory, revision and testing of drift-feeding models (specifically new, functional prey detection and interception sub-models), and revision of habitat selection/quality models to incorporate spatial, temporal, and flow-dependent variation in drift concentration.