Piscine diversity, Community structure and Distribution patterns of the West Ramganga River: A mid-Himalayan tributary of River Ganga

Abstract

The study documents the fish diversity, assemblage structure, distributional pattern and composition at different sampling sites along the stretches of the West Ramganga river of mid-Himalayas between 138 and 777 meters above sea level. Altogether 92 fish species representing 8 orders, 23 families and 64 genera were recorded. The most dominant family was Cyprinidae with 47 species (51%) followed by Bagridae with 7 fish species (8%). Labeo was the most dominant genera with 9 species, followed by Barilius (6), Garra and Mystus (4 species each). Species richness showed a trend of rapid decline along the altitude with highest records in the lowland sites, where ~93% of the total fish species recorded were between 138 and 320 masl. The Shannon Wiener Index (H’) was found to be maximum at R6 (3.254) followed by R7 (3.24) and R8 (3.074) sites, all constituting the lowland stretch of the river. Species composition showed a distinct assemblage of cold-water specific genera at higher elevation sites based on clustering As per IUCN status, one species each of endangered (Tor putitora) and vulnerable (Schizothorax richardsonii) category was reported from the river, while 6 species reported, fell into near threatened category (Tor tor, Labeo pangusia, Wallago attu, Ompok pabda, Hypophthalmichthys molitrix, Bagarius bagarius and Ailia colia). The high fish species richness in the river Ramganga provides an updated information for the policy makers to plan suitable conservation measures which is currently lacking in most of the threatened freshwater ecosystems especially in the Himalayan river basin.