Asian river dolphins
Asian river dolphins are among the most threatened large vertebrates, because the regions they inhabit have high human population density, resource overexploitation and environmental degradation, with escalating pressures on local biodiversity and diminishing ecosystem services.
©John Goold Following the extinction of the Yangtze River dolphin, the Endangered Ganges and Indus River dolphins are now the world’s most threatened freshwater cetaceans.
Few robust data are available on their regional status or the significance of different drivers of their ongoing decline, but they are threatened by overfishing (resource depletion, by-catch, direct exploitation), habitat alteration, water development projects, industrial, agricultural and domestic pollution in their range, and little is known about other threats such as disease.
Because these threat processes also have wider impacts on freshwater biodiversity and human communities dependent upon freshwater resources, long-term dolphin conservation must also address factors including maintenance of fish stocks and water quality within a wider-scale integrated conservation framework.
River dolphins are ‘flagship’ predators in Asian river ecosystems; establishing an improved scientific evidence-base on the dynamics of their population decline, in conjunction with research into the status of regional ecosystem services, increased regional conservation capacity-building, awareness-raising, and protective environmental legislation, will therefore not only permit development of sustainable recovery strategies for endangered dolphins but also provide long-term benefits for other species and communities that rely on the health of freshwater systems.
The Ganges River dolphin (Platanista gangetica gangetica) occurs in the Ganges-Brahmaputra-Meghna and Karnaphuli river systems of India-Nepal and Bangladesh, with a surviving population of up to 2000 individuals.
The Brahmaputra River system was until recently one of the last refuges containing relatively healthy dolphin populations, but research by the Assamese NGO Aaranyak indicates that this population is now highly threatened, experiencing severe decline, with less than 300 surviving individuals.
There is therefore an urgent need to develop a long-term integrated conservation programme for the Brahmaputra dolphin, involving leading research, applied conservation action, capacity building and environmental education/awareness.