A Unique Freshwater River Dolphin

Most dolphins and whales occur only in the salty water of the world's oceans. However, there are four specially adapted dolphin species which have evolved to live only in freshwater river systems and which would ultimately die in salt water. The Indus River dolphin (Platanista minor) or Bhulan occurs only in the Indus Rive and its tributaries in Pakistan. Other river dolphins occur in the Yangtze River in China, the Amazon in South America and the Ganges, Brahmaputra and Meghna river systems in India, Bangladesh and Nepal, respectively.

Physical Characteristics

Indus dolphins are mammals, not fish. Just like humans, they breathe air and give birth to live young, which feed on their mothers' milk.

Colour: Mostly mid grey-brown.

Size: the maximum size is 2.5m. Males are smaller than females.

Eyes: the dolphin is functionally blind and has no lens in its tiny eye.

Teeth: Adults have between 30 and 36 sharp teeth on each side of the upper and lower jaws. The teeth at the end of the rostrum are very long and protruding.

Rostrum: River dolphins have a much longer rostrum than oceanic dolphins. It can be up to one fifth of the body length.

Blowhole: Dolphins breathe through a blowhole located on the top of their head.

Neck: the neck is relatively narrow and very flexible which helps the dolphin move in a complicated river environment.

Flippers: Bhulans have very broad flippers which stabilize them at slow speeds in fast flowing water.

Distribution and Status

The Indus River dolphin occurs only in Pakistan, in the Indus River and its tributaries. Historically the dolphins were found right from the Indus estuary up into the foothills of the Himalayas. At present the dolphins occur only in small populations which have been separated by impassable barrages across the Indus River. It is estimated that there are about 1,100 Indus dolphins remaining in Pakistan. The species is listed as Endangered by the World Conservation Union (IUCN). The largest population is in Sindh between the Sukkur and Guddu and Taunsa, and then Taunsa and Chashma barrages.

A Blind Dolphin

For Indus dolphins being almost completely blind is not a disadvantage but an adaptation to living in a turbid river environment where eyes are virtually useless. Instead of eyesight, the dolphin has developed a high-tech echolocation or sonar system to effectively "see" its environment. Sound pluses are emitted into the water through the "melon" at the front of the dolphin's head; these sound pulses are reflected back to the dolphin telling it details about its surroundings. Using this echolocation system, they can navigate, as well as locate prey, objects such as boats and other dolphins.

Swimming Action

The Indus River dolphin often swims on its side. This behaviour enables it to swim in water as little as 30cm deep. As it swims on its side, it trails a flipper along the bottom of the river. After 30 to 60 seconds, when it needs to breathe, it swims to the surface, rotates upright to take in air, and then rotates through 90 again as it swims back to the bottom. This unique swimming behaviour is not routinely seen in any other dolphin except the Ganges River dolphin.

Reproduction and Life Span

Dolphins are pregnant for approximately 10 months and the babies are thought to be born in spring. When a baby is born it is about 70 cm long and the mother helps it to the surface to breathe. Babies stay close to their mother for the first six months of life. Scientists think that dolphins can live at least 20 years.

Threats

• Lack of Freshwater - Extensive irrigation schemes mean that during winter months there is very little water left in the Indus River for the dolphins to live in.

• Entrapment in Irrigation Canals - Sometimes dolphins swim along irrigation canals and become trapped in narrow channels where they die.

• Fisheries - Dolphins can become entangled in fishing nets in the river and drown.

• Pollution - The are many chemicals in the Indus River such as pesticides, organochlorines and industrial effluents. These can enter the dolphin's body and reduce their physical fitness making them more prone to illness or reproductive problems.

• Fragmented habitat - Indus dolphins have been split into several small populations separated by inbreeding which can result in reduced fitness or physical deformities.

If you see an Indus River Dolphin - Call us!

If you find a dolphin trapped in an irrigation channel or in distress please call our scientists sow we can try to save it. Or if you see a dolphin in the Indus River or its tributaries, we would like to hear about it. Please contact us at: WWF - Pakistan, Ferozepur Road, PO Box 5180, Lahore 54600.