Field Evaluation and Simulation Modeling of Length Limits and their Effects on Fishery Quality for Muskellunge in the New River, Virginia

Abstract

AbstractThe trophy fisheries for Muskellunge Esox masquinongy in the northern U.S.A. and Canada often are developed and maintained by using high minimum‐length limits (MLLs). However, the effectiveness of using such MLLs on southern‐latitude Muskellunge populations, which have different rates of growth and mortality, warrants further research. The Muskellunge fishery in the New River, Virginia, was managed under a 30‐in (75 cm) MLL until 2006 when the MLL was increased to 42 in (105 cm) to increase the abundance of large Muskellunge. We measured fishery quality before and after the institution of the 42‐in MLL using size structure, average individual condition, rates of growth and mortality, and CPUE. We also assessed the potential of alternative length regulations (other MLLs and a 40–48‐in protected‐slot limit) to improve the population's size structure and trophy production using simulation models in the Fisheries Analyses and Modeling Simulator (FAMS) program. Following the institution of the 42‐in MLL, we observed a 5‐in increase in the average size of Muskellunge, an increase in the population's size structure with greater proportions of memorable‐size individuals (≥42 in) and an increase in the abundance of memorable‐size Muskellunge. However, declines in the average condition, i.e., relative weight (Wr), of large Muskellunge (≥38 in) suggest there is possible stockpiling of individuals just below the 42‐in length limit. Higher MLLs (e.g., 48‐in MLL) could further improve fishery quality by increasing the survival of Muskellunge to large trophy sizes (≥50 in). However, managers should be wary of stockpiling under alternative MLLs as well. Furthermore, a higher MLL is unlikely to garner broad angler support in this system. Conversely, a protected‐slot limit that allows the production of some trophy‐sized Muskellunge while reducing the overall number of individuals, and that limits potential for stockpiling, may be a more agreeable regulatory option for New River fishery managers. These findings and the methods described within this study may be useful for fisheries managers working on other Muskellunge fisheries in southern systems.