Simulation Modeling to Explore the Effects of Length-Based Harvest Regulations for Ictalurus Fisheries

Abstract

Management of Blue Catfish Ictalurus furcatus and Channel Catfish I. punctatus for trophy production has recently become more common. Typically, trophy management is attempted with length-based regulations that allow for the moderate harvest of small fish but restrict the harvest of larger fish. However, the specific regulations used vary considerably across populations, and no modeling efforts have evaluated their effectiveness. We used simulation modeling to compare total yield, trophy biomass (B_trophy), and sustainability (spawning potential ratio [SPR] > 0.30) of Blue Catfish and Channel Catfish populations under three scenarios: (1) current regulation (typically a length-based trophy regulation), (2) the best-performing minimum length regulation (MLR_best), and (3) the best-performing length-based trophy catfish regulation (LTR_best; “best performing” was defined as the regulation that maximized yield, B_trophy, and sustainability). The B_trophy produced did not differ among the three scenarios. For each fishery, the MLR_best and LTR_best produced greater yield (>22% more) than the current regulation and maintained sustainability at higher finite exploitation rates (>0.30) than the current regulation. The MLR_best and LTR_best produced similar yields and SPRs for Channel Catfish and similar yields for Blue Catfish; however, the MLR_best for Blue Catfish produced more resilient fisheries (higher SPR) than the LTR_best. Overall, the variation in yield, B_trophy, and SPR among populations was greater than the variation among regulations applied to any given population, suggesting that population-specific regulations may be preferable to regulations applied to geographic regions. We conclude that LTRs are useful for improving catfish yield and maintaining sustainability without overly restricting harvest but are not effective at increasing the B_trophy of catfish.

Received February 1, 2016; accepted June 16, 2016

ACKNOWLEDGMENTS

We thank Steve Miranda for constructive comments that improved this manuscript. Financial support for this publication was provided by Oklahoma State University and the Oklahoma Cooperative Fish and Wildlife Research Unit (the U.S. Geological Survey, Oklahoma State University, Oklahoma Department of Wildlife Conservation, Wildlife Management Institute, and U.S. Fish and Wildlife Service cooperating). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.