Assessing shoal bass habitat use from low-cost side scan sonar and electrofish data

The Lower Flint River (LFR) is a medium sized (90-130 m) river in southwest Georgia and home to a variety of endemic species, including the shoal bass (Micropterus cataractae).  A long standing fisheries management objective has been to map, quantify and classify LFR shoals, which serve as important spawning, nursery, and foraging areas for resident fish. Traditional methods of assessment, however, were deemed costly and ineffective due to water depth, turbidity, and scale. Instead we employed our low-cost approach that utilizes a HumminbirdSide® Imaging system ($2,000), global positioning systems (GPS), and ArcGIS 9.x geographic information system (GIS) software to capture and produce georeferenced sonar image maps (SIMs) spanning 122 kilometers of the LFR.  The resulting SIMs, high resolution (~10 cm) GIS layers revealing continuous bottom habitat, were accuracy assessed and used to map and classify shoal habitat according to size, depth and spatial proximity to other habitats. GIS layers representing classified shoal habitats are being analyzed against spatially referenced shoal bass electrofish data to identify shoal use and preference patterns.