Mammals

Individuals spend most of their time feeding and travelling alone, although groups of 5-7 are sometimes seen in areas where the current is relatively weak and there is a high abundance of prey. Small fish and invertebrates are the main prey species. Most feeding takes place in shallow areas at or near the bottom, with the dolphin swimming on one side and probing the substrate with its beak or flipper. Individuals use echolocation to detect food and navigate, and – to a very small extent – for communication. The dolphins migrate seasonally according to fluctuations in water levels. They spend the dry season in deep pools or the main channels of the river systems, and migrate upstream to the tributaries following the monsoon. Births may take place throughout the year, but appear to peak in December-January and March-May. A single calf is born every two years. Juveniles are weaned at around one year of age, but do not reach sexual maturity until around 10 years of age. This species is thought to live to around 28-30 years in the wild.

This species is found in freshwater river systems. In the river basins in India the dolphin is present mostly in plains with slow-flowing rivers. In Nepal it is found in relatively clear waters and rapids. In both areas, however, there is a preference for deep waters. The dolphins tend to concentrate in areas of high prey availability and reduced flow, such as eddy counter-currents.

In Pakistan, the dolphins generally occur in the deepest river channel and are less common in secondary channels. Reported habitat preferences include channel constrictions, confluences (where rivers or streams converge), and deep water.

Surveys of portions of the range of the Ganges subspecies have collectively accounted for 1,200–1,800 animals, but the true population is believed to be larger. The entire current range of the Indus subspecies was surveyed in 2001 and resulted in an estimate of 843–1,171 individuals, with a best estimate of about 965.

Decreasing.

Classified as Endangered (EN A2abcde) on the 2010 IUCN Red List of Threatened Species.

P. gangetica gangetica lives in one of the most densely populated areas of the world. It is threatened primarily by the damming of rivers for irrigation and electricity generation, which degrades habitat, isolates populations and prevents seasonal migration. More than twenty barrages (low, gated diversion dams) and eighteen high dams have been constructed in the Ganges-Brahmaputra-Megna and Karnaphuli-Sangu river systems alone since 1956, and in the northern Ganges tributaries at least three of six subpopulations that were isolated by barrages have recently disappeared. Many individuals swim downstream through barrage gates during the wet season, but are unable to return in the dry season due to strong downstream hydraulic forces at the gates. Further declines are expected as more barrages are planned and under construction throughout the species’ range. The proposed Ganges-Brahmaptura inter-link canal and dam project, expected to be completed in India in 2016, will involve additional dam construction and diversion of water from rivers inhabited by dolphins. This will undoubtedly result in further habitat loss and degradation, population fragmentation, and an increase in dolphin strandings. Pollution by fertilisers, pesticides and industrial and domestic effluents are responsible for the death of many fish and are likely to have a negative effect on dolphin populations. Other threats include deliberate killing of the animals for their meat or oil (used as catfish bait), and accidental entanglement in fishing nets. The latter is a severe problem for this species since its preferred habitat is often in the same location as primary fishing grounds.

P. gangetica minor is threatened primarily by the damming of rivers for irrigation and electricity generation, which degrades habitat, isolates populations and prevents seasonal migration. The construction of three irrigation barrages, completed at Sukkur in 1932, at Kotri in 1955, and at Guddu in 1969, has had a devastating effect on the species. They have severely fragmented the population and reduced the volume of water, particularly downstream of the Sukkur Barrage, causing the dolphins’ dry-season range to shrink. Subpopulations on either side of barrages are now isolated and thus are more vulnerable to extinction due to hunting or environmental change. It has been hypothesised that individuals may swim downstream through barrage gates during the wet season or during canal closure, but are unable to return due to strong downstream hydraulic forces within the barrage gates. Since the mid 1990s, there have been increasing reports of dolphins trapped in irrigation canals near Sukkur Barrage, many of which die when the canals are drained for annual de-silting and maintenance. Further declines are expected as more dams are planned upstream of the dolphins range, and increasing demands for water in Pakistan will likely further deplete dry season river flows. Other threats include accidental entanglement in fishing nets and entrapment in irrigation canals.

The species is legally protected throughout its range. It is listed on Appendix I of CITES and Appendix I of the Convention on Migratory Species (CMS or the Bonn Convention). However, poaching still occurs in some areas, and greater enforcement of laws is required. The Upper Ganga River (Brijghat to Narora, in the state of Uttar Pradesh) has been declared as a Ramsar site because of the presence of dolphins there. The population in this stretch has doubled in the last 10 years due to conservation work conducted by WWF-India along with the local community. The Vikramshila Gangetic Dolphin Sanctuary, between Sultanganj and Kahalgaon in the mainstem of the Ganges River in Bihar, India, was designated as a protected area for dolphins in 1991, although until recently there has been little enforcement of protective measures here. In a few smaller tributaries, dolphins receive nominal protection by virtue of the fact that small portions of their habitat are within or adjacent to national parks and sanctuaries (e.g. Kaziranga National Park in Assam, India; National Chambal Sanctuary in Madhya Pradesh, India; Royal Bardia National Park and Katerniya Ghat Gharial Sanctuary, respectively north and south of the Nepal-India border). It has been recently found that fish oils can be used in the place of Ganges River dolphin oil for the preparation of bait; popularization of fish oil bait will hopefully reduce the poaching of the dolphin for its oil.

In Pakistan, the area between the Sukkur and Guddu Barrages was declared a dolphin reserve in 1974 (the Sindh Dolphin Reserve), and dolphin counts here show an apparently increasing trend from 1975 to 2001. Two additional sanctuaries, the Taunsa Wildlife Sanctuary (est. 1983) and the Chashma Wildlife Sanctuary (est. 1984) in Punjab Province also appear to be helping to arrest the rapid population declines. A programme sponsored by the United Nations Development Programme (UNDP) to rescue dolphins trapped in irrigation canals and return them to the Indus mainstream has had some success in reducing mortality.

Although the population has declined dramatically, it is still large enough to be viable in the long-term if adequate conservation measures are taken soon. The International Whaling Committee (IWC) recommends that surveys be carried out to assess the current distribution and abundance of the species, and to assess the availability of suitable habitat. Further research into the main threats facing the species is required in order to implement effective conservation measures. Education and public awareness programmes are crucial to conservation efforts as many local people are unaware of the dolphin’s protected status and regulations. The creation of additional areas of protected habitat and/or dolphin sanctuaries may be required to ensure this species’ long-term survival.

In Pakistan, efforts to ensure the Sindh Dolphin Reserve population remains well-protected are crucial, as is the creation of additional areas of protected habitat upstream of the Guddu Barrage. The International Whaling Committee (IWC) recommends that priority be given to monitoring the survival and movement of dolphins rescued from irrigation channels. Surveys should also be carried out to assess the current distribution and abundance of the species, and to assess the availability of suitable habitat. Further research into the main threats facing the species is required in order to implement effective conservation measures. In particular, the effects of barrages and canal gates on dolphin movements need to be determined. Finally, education and public awareness programmes are crucial to conservation efforts as many local people are unaware of the dolphin’s protected status and regulations.

Aaranyak
Aaranyak, a registered conservation NGO working in North East India since 1989, has initiated a project entitled “Conservation of Gangetic dolphin in Brahmaputra river system, India" in collaboration with Dibrugarh University (Assam). The project aims to evaluate the conservation status of the Ganges River dolphin throughout the entire Brahmaputra river system by carrying out research into the species’ population status, distribution, habitat preferences and threats. The data collected will be used to inform the development of a conservation strategy and subsequent conservation action for the species.

Project leader: Wakid Abdul
Contact details: wakid@rediffmail.com

Whale and Dolphin Conservation Society (WDCS)
The Vikramshila Biodiversity Research and Education Centre (VBREC), led by Dr Sunil Chaudhary, together with the Whale and Dolphin Conservation Society (WDCS), the Environmental Biology Laboratory of Patna University, and T.M. Bhagalpur University, has initiated a project to improve the conservation value of the 50km Vikramshila Gangetic Dolphin Sanctuary. One of the most important accomplishments has been the development of the Vikramshila Conservation Action Plan.

WWF India
The Dolphin Conservation Programme of WWF-India has been engaged in various activities to conserve the habitat of the Ganges River Dolphin and secure a future for the endangered species. The Action Plan prepared by WWF-India in 1997, has been under implementation to bring about a sustainable improvement in the status of the Dolphin.

Key contact: Sandeep Behera (Freshwater- Species)
Address: WWF-India, Secretariat, New Delhi (IN) Main Office
T: +91 11 41504813

Convention on Migratory Species (CMS): Platanista gangetica, Ganges river dolphin

Nikaido, M., Matsuno, F., Hamilton, H., Brownell, R. L. Jr, Cao, Y., Ding, W., Zuoyani, Z., Shedlock, A. M., Fordyce, R. E., Hasegawa, M. and Okada, N. 2001. Retroposon analysis of major cetacean lineages: The monophyly of toothed whales and the paraphyly of river dolphins. Proceedings of the National Academy of Sciences of the United States of America 98(13): 7384-7389.

Nowak, R. M. 1999. Walker’s Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Reeves, R. R., Smith, B. D., Crespo, E. A. and Notarbartolo di Sciara, G. 2003. Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World’s Cetaceans. IUCN: Gland, Switzerland.

Smith, B.D. & Braulik, G.T. 2008. Platanista gangetica. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. <www.iucnredlist.org>. Downloaded on 12 November 2010.

Distribution map based on data provided by the IUCN Global Mammal Assessment.