FUNCTIONAL AND NUMERICAL RESPONSES - A FRAMEWORK FOR FISH-ANGLER INTERACTIONS

A conceptual framework for sport fisheries in which fish-angler interactions are viewed as a dynamic predator-prey relationship was evaluated with data from the walleye fishery in Lake Mendota, Wisconsin. A detailed 7-yr creel survey data set for this fishery revealed a link between fish and angler dynamics. Angler catch rates were positively and linearly related to fish abundance over the range of data in the study. Angling effort was positively related to catch rate. Fish-angler relationships were obscured by three difficulties commonly associated with fishery data sets: seasonal responses, measurement errors in predictor variables, and time series bias. Statistical techniques removed each of these biases, but the data were still insufficient to conclusively identify an appropriate model for the interaction. Nevertheless, it is clear that assumptions of static angler response to sport fish manipulations are unwarranted and capable of seriously confounding management efforts. Interactions among anglers and the influence of alternative fisheries outside the observed system appeared to be important. A combination of longer duration studies on a broader geographic scale and manipulative management experiments is probably necessary to advance our understanding of fish-angler interactions.