Ichthyofaunal diversity of lower reaches of the Brahmaputra River, Assam.

An investigation was carried out from February 2009 to January 2010 in the core fish landing centres of Goalpara district, Assam to evaluate the present status of ichthyofaunal diversity of the lower reaches of Brahmaputra River. A total of 97 species including exotic species belonging to 56 genera of 26 families were recorded from all the fish landing centres. Among these, according to IUCN status, 5 species are endangered, 21 species vulnerable, 29 species lower risk-near threatened, 7 species lower risk-less concern and other 29 species are not evaluated. The families recorded were Notopteridae, Clupeidae, Engraulidae, Cyprinidae, Psilorhynchidae, Balitoridae, Cobitidae, Bagridae, Siluridae, Schilbeidae, Sisoridae, Clariidae, Heteropneustidae, Chacidae, Mugilidae, Beloniidae, Synbranchidae, Mastacembelidae, Chandidae, Nandidae, Cichlidae, Gobiidae, Anabantidae, Belontidae, Channidae and Tetradontidae. Seasonal variations of the fishes were also noticed remarkably. The taxonomic composition of the fish fauna suggests, Cyprinidae were the most dominant family with 39 representative species (42.8%) followed by Bagridae having 7 species (7.7%). The study reveals that lower reaches of River Brahmaputra is very rich in ichthyofaunal diversity. However, strategies such as controlled harvest, checks on growth of exotic species, controlling water pollution etc. are suggested for conservation of the native and endemic fish species of the region.