Fishing gear performance nearshore is substantiated by spatial analyses

We estimated whether the fish assemblages nearshore represented by electrofishing and gillnetting indexed location of reservoirs in a river basin. We expected that location in the basin would reflect a multiplicity of factors that determine fish habitat and fish assemblage composition, and therefore also anticipated a correlation between fish species composition and spatial variables if the gear type reflected legitimate differences in fish assemblages. We collected 1.6 million fish of 129 species in 22 reservoirs of the Tennessee River basin, USA. Standardized electrofishing represented different aspects of the fish assemblages than standardized gillnetting. Nevertheless, the assemblages documented by each gear type were correlated with the spatial location of the reservoirs in the river basin. Thus, even as these gear types reflected different aspects of existing fish assemblages, they each tracked spatial differences, suggesting that they reflected standing fish assemblages. Our study supports the use of standardized boat electrofishing and gillnetting as proper means for monitoring fish assemblages at large spatial scales. Our results further suggest that a well-designed and standardized sampling protocol can in fact provide an informative bird's eye view of fish assemblages at regional, national, or continental scales suitable for informing conservation programs.