Influence of Multi-Scale Factors on Fish Structural Indices in Freshwater Impoundments: Implications for Successful Fisheries Management

Fisheries biologists manage waterbodies similarly, but fish communities within these waterbodies can differ across locations.  This disparity in fish condition can create uncertainty as to appropriate management strategies for a particular waterbody.  To examine how fish communities differ across waterbodies and how to successfully manage these differences, we conducted an investigation into the influence of multi-scale factors on fish condition.  We sampled fish via electrofishing in 26 impoundments throughout Georgia, USA, and we calculated relative weight and proportional stock density for sportfish species.  We used empirical sampling and geographic information systems to obtain measurements for multi-scale factors including mean depth, land cover, and climate for each impoundment.   We used information theory, with hierarchical linear regression to evaluate the relationship between multi-scale factors and structural indices.  We found fish condition was predicted by both lake- and landscape-level factors such as impoundment age, land cover, and mean depth.  Management actions based on multi-scale factors may optimize fish condition and stock composition in freshwater reservoirs.  Because many landscape-level parameters (e.g., land cover and geologic composition) cannot be realistically manipulated, we present managers with activities that can be employed in an economical and a practical manner to successfully manage freshwater fisheries.