Diversity and Threat to Cold-Water Fishes of the Torsa River at the Terai Region of West Bengal, India

Abstract

Rivers are the lifeline of mankind and provide livelihood to the riparian. Biodiversity is an important issue for environmental and biological stability. Biodiversity totally depends on climate, temperature, and natural resources. A huge diversity of flora and fauna are present in Terai and Duars regions of North Bengal, India. The Terai region of West Bengal has the Torsa River as a perennial river with a total length of 358 km. Its origin is from the Chumbi Valley in Tibet, which later joins Kaljani at Balarampur, North Bengal, India, and finally meets with the Brahmaputra by the name of Kaljani in Bangladesh. The Torsa receives a tributary of the Raidak River 29 km southeast of Koch Bihar. More than 100 ichthyofaunal diversities are recorded from this stretch. Cyprinidae, Bagridae, Sisoridae, and Cobitidae are the dominating families in Torsa River and its tributaries. However, there are several threats encountered to destroy the fish diversity and their environment. Some of the natural factors like alteration of river flow and sedimentation and anthropogenic factors like water pollution, overfishing, and use of nonconventional fishing gear indicate that the ecosystem is at risk. According to IUCN, 22 species are categorized under the “rare” or “very rare” category. There is an urgent need to investigate further the declining trend of fish species for their conservation. Nevertheless, socioeconomic development is nearly absent in this area. It is also marked by the accumulation of varied natural resources like forest, water (both surface and subsurface areas), medicinal plants, ferns and fodders, etc., including human resources. The present chapter explores the possibilities of optimum utilization of resources toward the fulfillment of fishery management and rapid economic upliftment of the people residing in and around.