Use of vehicle counters to index and evaluate potential shifts in angler effort following implementation of more restrictive panfish regulations in Wisconsin lakes

Abstract Objective Understanding angler responses to fisheries management actions, such as regulation changes, has important implications for the effectiveness and efficacy of such management strategies. We examined whether vehicle counters could provide a relative index of angler effort, and we present a case study demonstrating use of vehicle counters to assess potential changes in angler effort associated with implementation of more restrictive panfish regulations in a subset of Wisconsin lakes. Methods We compared vehicle counts with compulsory creel- and game-camera-based estimates of angler-hours and the number of angling parties. During 2016, a series of more restrictive panfish regulations were implemented across 132 Wisconsin lakes. We deployed vehicle counters at a subset of lakes within each regulation type during preregulation (2015–2016) and postregulation (2021–2022) time periods to assess whether the distribution of angler effort (as indexed using vehicle counters) among regulation types shifted in response to regulation implementation. Result At lakes with paired vehicle counters and compulsory creel data, vehicle counts explained 57–72% of the variation in daily angler effort (h) and 65–84% of the variation in daily number of angling parties. Across lakes with paired vehicle counters and game cameras, vehicle counters explained 63–77% of the variation in the number of apparent angling parties depending on how lakes were grouped (i.e., combined or stratified by regulation type); however, effectiveness of vehicle counters for explaining the variation in number of apparent angling parties varied at the individual lake level. We did not observe any systematic shifts in effort that would indicate a redistribution of angler effort in response to panfish regulations. Conclusion Results suggest that given appropriate validation measures, vehicle counters could be used as a cost-effective tool to index angler effort. Our findings indicate that a localized scale for implementation of specialized regulations may be appropriate given angler behaviors and preferences for Wisconsin panfish.