A study of the winter congregation sites of the Gangetic River Dolphin in southern Assam, India, with reference to conservation

Abstract

The Gangetic River Dolphin (Platanista gangetica gangetica) is an exclusive river dolphin subspecies and inhabits the freshwater river systems of India, Nepal and Bangladesh. This cetacean is primarily piscivorous and strictly inhabits the freshwater ecosystems, chiefly rivers. They generally wander to different parts of the river in the monsoon, but congregate at meander bends in the river course where an eddy counter-current is prevalent and there are greater water depths during winter months. These meander bends are locally called ‘Dhar’ in the Barak river of southern Assam. The dolphin population in this river and its tributaries and distributaries has declined steeply in the recent past. Although certain factors have been identified, reports on these dolphins are extremely limited. The present study was carried out at the reported and possible winter aggregation sites in the Barak river, its tributaries and one of the distributaries, the Kushiyara river, to find the present status of the dolphin and its habitats, along with prey fish abundance, threats and possible conservation strategies. We also conducted a survey on the responses of the local people, generally the fisher-folks, towards different dolphin conservation issues. Keywords: Barak river, Conservation, Gangetic River Dolphin, Platanista gangetica gangetica, Physicochemical parameters, Southern Assam