Case Studies in Fisheries Conservation and Management: Applied Critical Thinking and Problem Solving

Case 12: A Protected Slot Length Limit for Largemouth Bass in a Small Impoundment: Will the Improved Size Structure Persist?


Protected slot length limit regulations (e.g., fish between 30 and 38 cm must be released; fish larger and smaller than the slot can be harvested, depending on daily creel limits) have been used to restructure high-density, slow-growing largemouth bass populations in small impoundments (Flickinger et al. 1999; Noble and Jones 1999). Here, we will detail the simulation of a 30–38 cm (12–15 in) protected slot length limit. Largemouth bass smaller than the protected range were removed annually from a privately owned pond by spring nighttime electrofishing for four years. The largemouth bass size structure increased significantly by the fifth year. The study was then terminated. No further angling occurred, and no further removal occurred. Seven years later, you are hired as a fisheries consultant by a private conservation group that has just purchased the property. Your challenge in this case study is to predict the largemouth bass population size structure in this pond 7 years after management efforts ceased.

When anglers have been willing to harvest the small largemouth bass, a protected slot length limit can result in improved bass size structure (e.g., Eder 1984; Gabelhouse 1987; Novinger 1990; Neumann et al. 1994). Typically, the management goal is to reduce the density of sub-slot fish, improve growth rates, and increase size structure, often to that of a “balanced” population (e.g., proportional size distribution [PSD; Guy et al. 2007] of 40–70 [Anderson and Neumann 1996] and relative weight [ Wr] values of 95–105 [Blackwell et al. 2000]).