Spatial Modeling of Aquatic Habitat From a Fish's Perspective

Patchy distributions of organisms and environmental conditions are characteristic traits of aquatic environments. Yet biological and physical measurements are often averaged over large spatial scales when used in environmental models. From a fish's perspective, local rather than spatially averaged conditions determine available habitat. We found that a horizontal cell size of 40 m preserved environmental heterogeneity in habitat quality analyses. Habitat quality was quantified using prey density, prey size, and water temperature data in bioenergetic models to estimate the potential growth of adult walleye (Stizostedion vitreum vitreum) in Lake Erie. Maps of potential growth rates showed that walleye growth is more sensitive to changes in water temperature than to changes in prey density. Addition of a programing language or increasing the flexibility of data formats would increase the use of commercial GIS systems in environmental modeling.