Status, distribution, threats, and conservation of the Ganges River Dolphin Platanista gangetica (Mammalia: Artiodactyla: Cetacea) in Nepal

Abstract

The Ganges River Dolphin Platanista gangetica has been classified as Endangered in the IUCN Red List of Threatened Species. The IUCN changed its status from ‘Vulnerable’ to ‘Endangered’ in 1996 as the species population was declining in its entire distribution range. It is, however, classified as ‘Critically Endangered’ in Nepal. Historically, the freshwater cetacean has been documented in the Karnali, Koshi, Narayani, and Mahakali basins. With their population and distribution range in decline, the Ganges River Dolphin (GRD) is no longer found in the Mahakali River system, which demarcates and traverses the Western border of India and Nepal. This study examines the status and distribution of the GRD in the river systems of Nepal during the monsoon of 2016. The national dolphin population survey was conducted in the three largest river basins in Nepal—Karnali, Narayani, and Koshi. Each of the three basins represent the extreme upstream limit of the GRD distribution in Ganges River basin. The national population survey included both a boat-based survey and shore-based synchronized counting in each of the three river systems. Fifty-two (Best-High-Low: 52-61-50) dolphins were counted during the entire nationwide survey, conducted in July–August, 2016. Researchers gathered social-data from locals residing alongside the observed basin, giving priority to artisanal fishers and those subsisting to some degree from the rivers known to host the river dolphin. A questionnaire survey of ninety-two residents from riparian villages adjacent to the GRD hotspots sheds light on the local perspectives towards dolphin conservation coupled with an assessment of their socio-economic status; artisanal fishing practices; and their awareness of dolphin conservation. According to the survey, notable threats to dolphin conservation are prey depletion; non-availability of suitable habitat; habitat fragmentation and a low level of awareness. Based on the counting outcomes and social survey, recommendations have been put forward for the conservation of this species.

Keywords

• conservation
• ganges river dolphin
• large rivers
• national survey
• nepal