Factors Affecting Black Bass Species Composition in Louisiana Gulf Slope and Lower Mississippi Alluvial Valley Streams
Michael D. Kaller, Tiffany E. Pasco, William E. Kelso, and Debra G. Kelly
Abstract.—Historic reports and museum records describe a distinct spatial distribution pattern and habitat partitioning between Largemouth Bass Micropertus salmoides salmoides and Spotted Bass Micropterus punctulatus. However, beginning in the mid-20th Century, the literature describes more co-occurrences and less species specificity among habitats and distributions. Herein, we conducted a retrospective analysis of recently collected data (2005–2014) to assess: (1) how current distributional patterns of Spotted Bass and Largemouth Bass compare with historic distributions in Louisiana; (2) evidence of species-specific habitat associations based on abundance and habitat data collected; and (3) whether the Florida Largemouth Bass M. salmoides floridanus stocking program has affected Spotted Bass populations in adjacent river systems. Analyses of 68 wadeable streams and rivers indicated that current spatial distributions matched historic descriptions for 6 of 9 major drainages, with evidence still supporting distinct habitat associations for each species. Importantly, Spotted Bass did appear to be negatively influenced by widespread Largemouth Bass stocking. Further, construction of reservoirs across the state and landscape conversion from wet prairie and forest to intensive agriculture may have negatively impacted both species. Overall, habitat alteration and loss was the most widespread explanation for declines in Spotted Bass, with Largemouth Bass stocking of secondary and more localized importance.