Spatially-explicit Models of Fish Growth Rate

Abstract

Local density-dependent processes may significantly affect production dynamics at the population and ecosystem level. These processes are often nonlinear and occur at rates strongly influenced by the physical habitat. The spatial patchiness of both fish density and habitat has hampered our ability to separate the effects of density and habitat on production. In this paper, we introduce the concept of fish growth rate potential. Growth rate potential integrates physiologically-based models of fish growth rate with high-resolution spatial data on prey sizes, prey density, and the physical environment. By combining the strengths of bioenergetics models to simulate fish growth and of bioacoustics to measure fish density and size in a spatially-explicit framework, the approach overcomes some of the difficulties inherent in a spatially-patchy environment. The result is a two-dimensional, nonlinear model of fish growth and system production. Predator behavior and foraging algorithms provide additional model refinement. An example from Chesapeake Bay striped bass demonstrates that the spatial distributions and statistics of fish growth rate differ from those of the underlying physical and biological properties of the system. The integration of the two types of technologies improves predictions of how changes in spatial patterning and absolute scaling of the environment might affect individual and population growth rates and system production. © 1992 Taylor & Francis Group, LLC.