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Simulation modeling to explore the effects of length-based harvest regulations for Ictalurus fisheries

David R. Stewart·James M. Long·Daniel E. Shoup
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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.

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David R. Stewart, James M. Long, Daniel E. Shoup. 2016-09-13. Simulation modeling to explore the effects of length-based harvest regulations for Ictalurus fisheries. https://doi.org/10.1080/02755947.2016.1204391

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