Largemouth bass (Micropterus salmoides) on the Arkansas River have been regulated by a 381-mm minimum-length limit (MLL) regulation since 1 January 1998; however, little evaluation of this regulation has been conducted. During 2004-2005 and 2010, largemouth bass populations were sampled from throughout all navigation pools in the Arkansas River. All bass were aged using sagittal otoliths, and population metrics were calculated to conduct simulation modeling using the Fisheries Analyses and Simulation Tools (FAST) software. Composite model parameters were developed using data from all 3 yrs of sampling. Model predictions of fishery yield, average size of harvested fish, and number of preferred-sized (≥381-mm TL) fish in the population were compared among the current MLL and three alternative limits: 430 mm (higher than the current MLL), 330 mm (lower than the current MLL), and 255 mm (representing no MLL). At the relatively low levels of fishing mortality present in the Arkansas River fishery (μ ~ 12% from creel surveys), fishery yield would be improved with a lower or no MLL. Conversely, the 380-mm and 430-mm MLLs were predicted to have better potential to improve mean size of harvested fish and overall population size structure. Results of the population modeling indicated that the current 381-mm MLL regulation was an appropriate management strategy for the Arkansas River largemouth bass fishery, providing the best overall balance among fishery yield, mean size of harvested fish, and population size structure. However, a 330-mm or 356-mm MLL might be acceptable to accommodate competitive tournament anglers that are only interested in weighing in more bass.
