Fish diversity of Laster stream, a major tributary of river Mandakini in Central Himalaya (India) with regard to altitude and habitat specificity of fishes

Abstract

Laster stream is a major tributary of river Mandakini, which in turn is a major tributary of river Alaknanda. Stream traverses a distance of ~40 km before joining with river Mandakini at Suryaprayag (Tilwara) in Rudraprayag district (Uttarakhand), India. Present study reports existence of twenty one indigenous fish species belonging to eight genera, three families and two orders from the Laster stream. Schizothorax richardsonii (Cyprinidae family) was the dominating species followed by S. plagiostomus, Barilius sp., Tor sp., Noemacheilus sp., Pseudecheneis sp., Glyptothorax sp. The distribution pattern (diversity and abundance) of these species had negative co-relation with the increase in stream altitude. Habitat conditions in the stream varied considerably from headwater to main stream. Present study also describes the habitat specificity of fish assemblage. Maximum species diversity (18 species) was recorded from pool habitat and was the most preferred habitat. Least species diversity (09 species) was recorded from cascade habitat. Riffle and rapid habitat recorded no difference in species diversity.