Ganges river dolphin (Platanista gangetica)
|Also known as:||blind river dolphin, Ganges dolphin, Ganges susu, Indus River dolphin, South Asian river dolphin, susu|
|French:||Plataniste Du Gange, Sousou|
|Spanish:||Delfín Del Ganges|
|Size||Length: 210 - 260 cm (2)|
|Weight||80 - 90 kg (2)|
Classified as Endangered (EN) by the IUCN Red List (1). Listed on Appendix I of CITES (3) and Appendix II of the Convention on Migratory Species (CMS or the Bonn Convention) (4).
The Ganges river dolphin was recognised as a separate species in the 1970s, although some controversy remains surrounding its relationship with the Indus river dolphin (P. minor) (5). It has a fairly stocky body with a long beak that thickens at the tip, with light grey-brown skin that becomes paler on the body, often with a tinge of pink (6). The flippers are large and the dorsal fin is undeveloped, being more of a triangular ridge than a fin. The forehead rises steeply and the eyes are very small. Females tend to be larger than males (5). The local name ‘susu’ is said to refer to the noise this dolphin makes when it breathes (6).
This species inhabits parts of the Ganges, Meghna and Brahmaputra river systems in India, Nepal, Bhutan and Bangladesh, and the Karnaphuli River in Bangladesh (6).
A preference is shown for faster flowing, clear rivers in Nepal, but on the Indian Plains this species prefers slow-moving stretches of the Ganges (5).
Ganges river dolphins are usually solitary creatures (5). The eye lacks a lens and therefore functions solely as a means of detecting the direction of light. In the muddy waters of their habitat, good eyesight is not needed, and echolocation is used to detect food and navigate (7). Individuals tend to swim with one flipper trailing along the substrate, and will root around with their beak to disturb and detect the shrimp and fish upon which they feed (7).
Births may take place year round but appear to be concentrated between December to January, and March to May (5). After around one year, juveniles are weaned and they reach sexual maturity at about ten years of age (7). During the monsoon, dolphins tend to migrate to tributaries of the main river systems (5). Occasionally, individuals swim along with their beak emerging from the water (6), and they may ‘breach’; jumping partly or completely clear of the water and landing on the side of the body (6).
The Ganges drainage area is one of the most densely populated areas in the world, being home to roughly one tenth of the world’s human population, and as such suffers enormous demand for its resources. A major threat to the Ganges river dolphin has been the extensive damming of rivers for irrigation and electricity generation, which isolates populations and prevents seasonal migration (7). Other threats include chemical pollution, boat traffic, hunting and human disturbance. This species is hunted for oil, fish bait and food by local people; accidental entanglement in fishing nets also occurs (5).
International trade is prohibited by the listing of the Ganges river dolphin on Appendix I of the Convention on International Trade in Endangered Species (CITES) (3). It is also listed in the Agreement on the Conservation of Small Cetaceans of the Baltic and North Sea (ASCOBANS), under the auspices of the CMS (8). It is protected under the Indian Wildlife Act, although these legislations require stricter enforcement (5). Proposed conservation measures include designated dolphin sanctuaries and the creation of additional habitat. Further research into the current distribution and abundance of this elusive river-dweller is urgently required in order to implement effective conservation measures (5).
For more information on the Ganges river dolphin see:
The Whale and Dolphin Conservation Society
Convention on Migratory Species (CMS)
EDGE of Existence:
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- Dorsal fin: the unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
- Echolocation: detecting objects by reflected sound. Used for orientation and detecting and locating prey by bats and cetacea (whales and dolphins).
IUCN Red List (June, 2009)
- Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
CITES (June, 2003)
Convention on the Conservation of Migratory Species of Wild Animals (June, 2003)
CMS Report (June, 2003)
The Whale and Dolphin Conservation Society (June, 2003)
Animal Diversity Web (June, 2003)
ASCOBANS (June, 2003)