Evaluation of Potential Regulations for Improving Flathead Catfish Size Structure in Iowa’s Large Reservoirs
2021
Muhlbauer, Savannah R. | Krogman, Rebecca M.
Relatively little research exists for lentic populations of Flathead Catfish Pylodictis olivaris, particularly in northern states, such as Iowa, where there are currently no harvest restrictions but where the interest in trophy opportunities is growing. We assessed size structure, age structure, growth, condition, and survival for Flathead Catfish populations in Lake Red Rock and Rathbun Lake to increase our understanding of populations in Iowa and determine parameter values to be used in simulating potential regulations. Using low‐frequency electrofishing, we captured Flathead Catfish during July and August 2019; all fish were measured and weighed, and a pectoral spine was collected for age estimation. Archived data collected in 2010–2013 were also included in analyses. Reducing harvest by using two potential protected slot limits (PSLs; 305–381 and 381–432 mm) or a maximum length limit (no restrictions on fish <381 mm and a reduced bag limit for fish >381 mm) was simulated to determine effects on the percentage of quality‐ and preferred‐size fish. Simulations indicated that both PSLs and the maximum length limit produced a greater percentage of quality‐ and preferred‐size fish than a “no regulation” scenario, with PSLs being more effective at low exploitation (0.05) and the maximum length limit being more effective at higher exploitation rates (>0.10). An understanding of the current status of Flathead Catfish populations will allow managers to better manage these populations via informed decision making and help to protect them as their popularity with anglers increases.
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