Understanding movement, habitat use, and habitat selection by largemouth bass (micropterus nigricans x salmoides) and Alabama Bass (micropterus henshalli) on Lake Hartwell, South Carolina

Alabama Bass (Micropterus henshalli) were illegally introduced into the upper Savannah River Basin 15-20 years ago and have since become abundant as well as problematic ecologically. Acoustic telemetry was used to quantify diel movement, habitat use, and habitat selection of Alabama Bass and Largemouth Bass in Lake Hartwell, SC across seasons (June 2021-July 2022) with the goal of informing ongoing habitat enhancement efforts. Across all seasons, Alabama Bass conducted diel horizontal migrations from deeper offshore habitats during the day to nearshore, shallow habitats at night. Daytime Alabama Bass movement rates in offshore waters were higher than nighttime movement rates. Largemouth Bass remained in shallow, nearshore habitats during both day and night and moved less at night. When both species were nearshore at night, Alabama Bass used deeper habitats than Largemouth Bass potentially indicating habitat partitioning between species. During spring, Alabama Bass used deeper habitats compared to Largemouth Bass, suggesting differences in spawning habitats may exist. Discrete choice models revealed that Largemouth Bass had positive selection for all habitat structure classifications with the strongest odds of selecting installed woody structure during the day. Alabama Bass selection for rocky structures was highest across a diel time period while selection for installed course woody structures was weak. Our results suggest key differences in behavior and habitat use/selection of both species residing in the same system. Moreover, installed woody structures placed in shoreline habitats would likely benefit Largemouth Bass in Lake Hartwell while providing limited benefits for Alabama Bass