The Ganges River Dolphin, Platanista gangetica found in Sapta Koshi River. The Sapta Koshi River is a major wetland of Koshitappu Wildlife Reserve. The Ganges River Dolphin is a mammal primarily found in Sapta Koshi, Karnali and Narayani Rivers. The population size of Dolphin in Sapta Koshi River is unknown so far. However, three individuals had been observed in Sunsari Khola in 2019. The Sunsari River is connected with Sapta Koshi River. The Ganges River Dolphin population in Sapta Koshi River may be 3-5 individuals.
The Ganges River Dolphin is listed on the Appendix I of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). The IUCN listed Gangetic Dolphin as endangered on its Red List of Threatened Species. The Ganges River Dolphin is a protected mammalian species for Nepal since National Parks and Wildlife Conservation Act 1973 provided legal provision. Hunting and trade in the species and its parts and derivatives is completely prohibited.
Haphazard fishing, water pollution, fishing by poisoning, electric netting, uses of dynamite, siltation etc. poses threat to the conservation of this species.
An area actually the Ganges River Dolphin found lies beyond jurisdiction of reserve’s authority. That area is between down-flow of Koshi barrage to Gobargada. Now, this area has proposed to announce as buffer zone of Koshitappu Wildlife Reserve.