Susu (Ganges River Dolphin: Platanista gangetica gangetica)

Bhulan (Indus River Dolphin: Platanista gangetica minor)

There are currently two subspecies of blind river dolphin in the Ganges and Indus river basins. There is much debate as to whether these two subspecies should in fact be their own species as is reflected in different texts.

Subspecies: Ganges (P. gangetica gangetica)

Population size: There is a lack of meaningful population estimates on this species but they number certainly in the few hundreds and possibly as many as a few thousand throughout their fairly extensive range.

Distribution: The range of the Ganges dolphin is certainly contracting although it is still fairly extensive. It is found in the Ganges-Brahmaputra-Megna and Karnaphuli-Sangu River systems in India and Bangladesh. In addition there is a small but potentially viable population in the Karnali River in Nepal, now isolated by the Girija Barrage located just downstream of the Nepalese border with India.

Threats: Construction of dams and barrages has fragmented the metapopulation of Ganges dolphins and drastically altered it habits and habitat. The construction of embankments in Bangladesh has drastically affected the ecosystem where overflow and flooding are important cycles in the movements and spawning of floodplain dependent fishes. Dredging and development of the riverine environment, one of the most densely populated river environments in the world has altered the nature of the river environment and eliminated counter currents where the dolphins spend much of their time. Pollutants from industrialization and intensive agriculture are likely to increase and are already of major concern. In addition, the dolphins are incidentally killed through fishing activities and along a number of important stretches of their range, are deliberately killed for their meat and oil.

Interesting Facts: The Ganges dolphin is also known as the susu, a reference to the noise made as the animal breathes on the surface. It is currently recognized as one of two subspecies of blind river dolphin that use echolocation as their primary sense. They actually lack a lens to their eye and so are merely light sensitive. They are known to breach, jumping clear of the water and landing on their side. The Vikramishila River Dolphin Sanctuary in Bihar, India, is the only protected area for the susu in Asia, even here, it is often killed illegally.

Subspecies: Indus dolphin (P. gangetica minor)

Population size: Possibly less than 1000; a survey conducted recently along the entire known range resulted in a total count of 965 dolphins.

Distribution: Lives only in the Indus River in Pakistan, mainly along a 180km segment between the Guddu and Sukkur barrages in Sind province, its previous range much reduced by the establishment of the barrages. Historically it ranged throughout much of the Indus basin, including the Sutlej, Ravi, Chenab and Jhelum tributaries.

Threats: Barrages and irrigation canals, boat traffic, entanglement in fishing gear, pollution and poaching for oil and meat.

Interesting Facts: Sometimes called the bhulan, Indus susu and blind river dolphin, the Indus dolphin is small, grey-brown coloured with a long beak. It has many teeth that can be seen even when its mouth is closed and has a mouth line that curves upwards giving the impression it is always smiling. The Indus dolphin is virtually blind and uses echolocation as its main form of sensory perception due to the muddy nature of the Indus River water. It sometimes carries its young on its back, above the surface of the water and has the strange habit of swimming on one side with a flipper in the mud searching for food.