Mississippi River Basin Paddlefish Population Dynamics: Implications for the Management of a Highly Migratory Species

Photo credit: USFWS

Photo credit: USFWS

By Ryan N. Hupfeld, Quinton E. Phelps, Sara J. Tripp, and David P. Herzog

Abstract

Management of migratory fishes is a difficult task for fishery managers because fish cross jurisdictional boundaries and encounter differing regulations. States within the Mississippi River basin have differing commercial and recreational regulations for riverine Paddlefish Polyodon spathula populations, and the current population dynamics have not been evaluated on a system-wide basis. The objective of this study was to simulate the current reproductive potential of the population using various harvest scenarios. At the current exploitation rate of all locations pooled (u = 14.8%), the population may experience recruitment overfishing at a 610 mm minimum length limit and has the potential to experience recruitment overfishing at a 710 mm length limit (u = ~20%). Any added stressors (e.g., Asian carp) may cause further mortality; thus, adopting a precautionary approach is necessary to maintain sustainable Paddlefish fisheries. At an 810 mm length limit, the population would not realistically experience recruitment overfishing. Implementing a basin-wide minimum length limit of at least 810 mm on riverine Paddlefish fisheries is suggested. Given the migratory nature of Paddlefish, developing a form of governance to ensure management strategies are complementary, and a sustainable source of funding is available is imperative to ensure sustainability. To accomplish this, developing a Mississippi River Basin Interstate Fishery Commission may be beneficial.