Statement of Problem: The use of bioenergetics models in conjunction with models of foraging behavior to predict fish production estimates is a fairly well accepted practice for fisheries managers providing the ability to estimate the maximum sustainable production for a fisheries resource. Based on measured temperatures and estimates of available food resources, the manager can then use these estimates to set fishing and stocking quotas for an aquatic system. A primary assumption of this approach is that the fish species being modeled distributes itself in a manner that represents average, overall conditions or optimizes growth. As long as these assumptions are valid, the overall approach can be very valuable. However, if these assumptions are invalid and the fish species of concern distributes itself based on temperature, food, or some other factor alone, the overall approach could result in substantial errors in production estimates and incorrect fish stocking quotas. This study attempts to assess the importance of distribution behavior assumptions to fish stock predictions through the use of model simulations of an individual based, spatially-explicit model. The initial model is being developed based on already existing bluegill sunfish (Lepomis macrochirus) data. However, the approaches taken and model structures being developed are designed to be generic enough to use with any fish species. The information gained from concurrent studies on bioenergetics of endangered suckers in the Klamath Basin and lake trout in Jackson Lake, Wyoming and movement of endangered pallid sturgeon in the missouri river are intended to provide some of the parameters needed to developed such models for these species.
Objective: This study attempts to assess the importance of these behavior assumptions to fish stock predictions through the use of model simulations of an individual based, spatially-explicit model of bluegill sunfish (Lepomis macrochirus). In order to accomplish this objective, this study brings together many of the current theories regarding habitat choice in fishes and models them in all of their possible combinations under a set of a few plausible initial conditions.