The blind dolphins of the Indus

This rare species of mammal faces extinction and authorities in Pakistan are doing all they can to help the few remaining to thrive.

The River Indus is one of the longest rivers in the world. It is formed by the convergence of Himalayan glacial streams and passes through two of the world's tallest mountain ranges before flowing into the Arabian Sea. The major tributaries of this mighty river are the Sutlej, Ravi and Chenab.

This mighty river has for centuries, been host to the blind dolphin (Platanista minor). Although it has a closely related cousin (Platanista gangetica) that lives in the Ganges River in India, this dolphin has some distinctive features that place it in a separate subspecies.

Until the late Pliocene, (the geological time scale that extends from 5.332 million to 1.806 million years before present) the Indus and Ganges, along with some smaller tributaries formed one river. About five millennia ago, tectonic plate shifts meant that the rivers separated. The two river dolphins then evolved in their specific habitats — although given the geographical time scale of the rivers' separation, there is a surprisingly low genetic difference between the two subspecies.

Locals refer to this small mammal as bhulan while the term used in India for the Platanista Gangetica is susu. The characteristics that set this dolphin apart in its class is the long beak it exhibits and the fact that it has no eye lens which effectively renders the animal blind. The bhulan navigates using echolocation to find fish, shrimp and other prey in the river bottom. It weighs 70-110 kg (155-245 lbs). The maximum size is 2.5m (8.2 ft), with males smaller than females.

Due to the fact that The Indus River dolphin swims on its side, trailing a flipper along the river bottom, it is able to move in water as shallow as 30 cm. The dolphin comes up for air every 30-60 seconds and rotates to breathe before rotating once more to swim back towards the river bed. This side-swimming behavior is unique to the Platanista. It also, sometimes, carries its young on its back above the water surface.

River dolphins are morphologically and phylogenetically distinct from marine dolphins and most are restricted to a freshwater ecosystem. Although there has been much debate as to what the genetic evolution pattern has been among this biological group and what its relation is to the better known marine dolphin, most scientists now believe that these dolphins belong to a class of one of the most ancient lines of mammals to have inhabited the Earth. There are four subspecies within this class — Inia, Pontoporia, Lipotes and the Platanista.

Cetaceans (the main class name for dolphins) are ecologically diverse — their habitats range from coastal to oceanic and from tropical to polar waters. Within this diversified group the side swimming, blind and highly endangered Indus River dolphin has long been recognised as the genus presenting the greatest total of modifications known in any cetacean.

Platanista minor is the second most endangered freshwater river dolphin and one of the world's rarest mammals. Today, approximately 1,100 specimens or less of this species exist in the River Indus.

It is included in the IUCN (the World Conservation Union) Red List of Threatened Species. In 1988 and 1990 the dolphin was listed as vulnerable under IUCN but since 2004 it has been included on the Red List. The Inia, which is found in the Yangtze River, has an even lower chance of survival with its population numbering about 100.

A healthy number of river dolphins is a good indicator of the availability of adequate and clean freshwater. Indus dolphin numbers have declined due to a number of factors which include dam building, fishing net entanglement, boat traffic and pollution. But a decrease in water levels is perhaps the most critical of all threats facing this species.

This fact has not been ignored by organisations such as the World Wide Fund For Nature (WWF, formerly known as World Wildlife Fund) and the Sindh Wildlife Department, who have launched a River Dolphin Initiative in 2005 with the objective of reducing the threats to river dolphins and porpoises in the Indus.

The Pakistan chapter of the WWF has also developed the Indus River Dolphin Conservation Project (IRDCP) which registers as one of its aims, the improvement of agricultural practices near the dolphin habitat to reduce the agrochemical pollution in the Indus River.

The project also organises activities such as awareness campaigns through a conservation centre and ecotourism.

The Indus dolphin has lived in the Indus far longer than human beings have inhabited its banks.

One hopes that these beautiful creatures will be saved so that later generations can continue to enjoy observing this rare and graceful link to an ancient world.