Understanding spatial and temporal patterns of fish diversity and assemblage structure vis-a-vis environmental parameters in a tropical Indian reservoir.

Reservoirs have been given priority as an important resource for fisheries enhancement in inland open waters. This paper described the spatial and temporal pattern of fish diversity using GIS platform, assemblage structure, and studied the influence of environmental parameters in these variables in a large tropical reservoir, Chandil, located in the eastern India using multiple approaches. Altogether, 42 fish species belonging to 30 genera were recorded from the reservoir, including two exotic species: pangas, Pangasianodon hypophthalmus, and Nile tilapia, Oreochromis niloticus. The diversity indices indicated lowest fish diversity in the lacustrine zone, but without distinct seasonal variation. The taxonomic distinctness was lower in the lacustrine zone as compared to other zones, and the summer season exhibited higher taxonomic distinctness, though the number of species was lowest. Most of the physicochemical parameters recorded are within the favorable range for fisheries enhancement. Among the environmental parameters, pH and nitrate significantly influenced the fish abundance. The study recommends suitable measures and interventions for conservation of the native fish diversity and sustainable fisheries development: closed season, protected/conservation area, introduction of fish aggregating device (FAD), and regulated fish culture in enclosures.