12 October 2010
Subject: Potential impacts of five large dams on the Endangered Gangetic dolphins in the Brahmaputra River Basin, India
The Board of the Society for Marine Mammalogy wishes to convey its concern about the future of the Gangetic dolphin (Platanista gangetica gangetica) in the Brahmaputra River system of India.
The Society for Marine Mammalogy consists of approximately 1,000 scientists from 60 countries and is dedicated to the study, understanding, and conservation of marine mammals and their ecosystems. Of the species of concern to our Society, river dolphins represent the most vulnerable to extinction because their entire distributions are in close proximity to humans. The first extinction of a dolphin known to have been caused by humans occurred just a few years ago and was of another river species in Asia: the baiji or Yangtze river dolphin.
We are very concerned about the future of Gangetic dolphins in the Brahmaputra River and its tributaries because of plans to construct multiple dams. We are particularly concerned about five of the almost 170 dams in the planning or construction stages that have the greatest potential to harm the Gangetic dolphins living downstream. These are the Lower Subansiri Dam (already under construction), the Lower Siang Dam, the Dibang Dam, Lower Damwe Dam, and Kulsi Dam. Individually, these dams are likely to result in declines in the range and abundance of Gangetic dolphins. Together, their cumulative impacts could lead to the complete disappearance of the species from the Brahmaputra River and its tributaries.
Only about 300 dolphins survive in the Brahmaputra system of India, as estimated from a recent survey by Dr Abdul Wakid, an internationally recognized expert on river dolphins in India. River dolphins depend on the relatively deep pools that form in particular portions of natural rivers, and this pool habitat will be degraded or even eliminated by the changes in river morphology and hydrology caused by the dams. The fluctuations in discharge associated with dam operation will also reduce fish diversity and abundance, further threatening dolphins.
We are also concerned that any reduction in fish diversity and abundance may have the potential to adversely impact the livelihoods of the local fishing people, which in turn may have consequential adverse effects on the dolphins through increased fishing effort.
We strongly believe that science should form the basis for management of natural resources and the conservation of biodiversity and that the future survival of the Gangetic dolphin would be significantly enhanced if the following actions could be taken:
- Conduct a comprehensive environmental impact assessment that explicitly includes the downstream impacts of the five dams, individually and cumulatively, on Gangetic dolphins and their prey.
- Conduct a comprehensive socio-economic impact assessment on the downstream impacts of the five dams, individually and cumulatively, on the local communities, especially the fishers.
- Develop a Brahmaputra Basin water development plan that ensures efforts to conserve Gangetic dolphins in one area are not undermined by dam construction in another area.
- Consider canceling plans for constructing one or more of the dams if the anticipated risks to the continued survival of the Gangetic dolphin are judged to be severe and cannot be reduced to acceptable levels.
The membership of our Society includes unparalleled expertise in river dolphin biology and risk assessment. We recognize the competing interests for precious water resources and offer our help and expertise in finding solutions that would allow humans and Gangetic dolphins to co-exist. We congratulate the Government of India for its recent declaration of the Gangetic dolphin (Platanista gangetica gangetica) as the National Aquatic Animal of India and hope that many generations of your citizens can enjoy and benefit from rivers with healthy dolphin populations.
Randall Wells, Ph.D.