The Performance of Rigid One-Size-Fits All vs. Adaptive HarvestRegulations in a Regional Freshwater Recreational Fishery with Mobile,Heterogeneous Anglers

A coupled social-ecological model of a freshwater open-access recreational fishery with heterogeneous, mobile anglers targeting northern pike (Esox lucius) is presented. The model is used to examine whether adaptive harvest regulations tailored to local stock status outperform non-adaptive (rigid) one-size-fits all harvest regulation alternatives. Five key insights were derived. First, active harvest regulation planning of a small set of minimum-length and daily bag limit combinations outperforms one-size-fits all harvest regulations in meeting three types of objectives (conservation, social and economic). Second, closing off collapsed lakes is of limited additional use provided that the other output-oriented harvest regulationsare sufficiently restrictive to avoid stock collapses and post-release mortalities are low. This result, however, was highly sensitive to the criteria in terms of the local spawning stock biomass triggering closures and to the degree of post release mortality. At high post release mortalities and large angler population size relative to available waters closing off collapsed fisheries generated important benefits by lowering regional overfishing and increasing regional biomass yield and harvest, at the cost of sometimes reducing angler welfare. Third, managers concerned with the efforts and costs needed to regularly monitor stock status canachieve a second-best alternative with a conservative one-size-fits all regulation (high minimum-length limit, and low daily bag limit), but this comes at a cost of reduced regional biomass yield. Fourth, at very high post release mortalities standard harvest regulations without effort controls could not avoid some level of overfishing and collapse, especially at high angler effort densities. Finally, a fine-tuned adaptive harvest management policy can beimplemented with relatively coarse sampling schemes where only a subset of lakes is assessed at broad sampling intervals, but this comes at a cost of reduced regional biomass yield andincreased among-year variation in outcomes. Insights from this study can serve as a defaultfor adaptive harvest regulation management in open-access recreational fisheries in freshwater landscapes.