Ganges River dolphin

A blind dolphin in one of the world's most densely populated area

The Ganges River dolphin, or susu, inhabits the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Nepal, India, and Bangladesh. This vast area has been altered by the construction of more than 50 dams and other irrigation-related projects, with dire consequences for the river dolphins.

The Ganges River dolphin lives in one of the world's most densely populated areas, and is threatened by removal of river water and siltation arising from deforestation, pollution and entanglement in fisheries nets. In addition, alterations to the river due to barrages are also separating populations. A recent survey conducted by WWF-India and its partners in the entire distribution range in the Ganga and Brahamaputra river system - around 6,000 km - identified fewer than 2,000 individuals in India.

This dolphin is among the four "obligate" freshwater dolphins found in the world - the other three are the baiji found in the Yangtze river in China, the bhulan of the Indus in Pakistan and the boto of the Amazon River in Latin America. Although there are several species of marine dolphins whose ranges include some freshwater habitats, these four species live only in rivers and lakes.

Public awareness and support for conservation of the Ganges River dolphin is virtually non-existent, and although the Wildlife Protection Act of India mandates dolphin conservation as a priority, little has been done at the government level to implement or enforce the law.

In 1997, WWF India developed a plan of action for the conservation of the Ganges River dolphin. WWF's objective for freshwater cetaceans is to ensure that habitat degradation and fisheries bycatch do not threaten any species of freshwater cetacean. Specifically for the Ganges River dolphin, WWF aims to reduce or eliminate the threats caused by fisheries bycatch and habitat degradation by 2012.

Physical Description

A long thin snout, rounded belly, stocky body and large flippers are characteristics of the Ganges River dolphin. Although its eye lacks a lens (this species is also referred to as the "blind dolphin"), the dolphin still uses its eye to locate itself. The species has a slit similar to a blowhole on the top of the head, which acts as a nostril.

The dolphin has the peculiarity of swimming on one side so that its flipper trails the muddy bottom. This behaviour is understood to help it to find food.

Being a mammal, the Ganges River dolphin cannot breathe in the water and must surface every 30-120 seconds. Because of the sound it produces when breathing, the animal is popularly referred to as the 'Susu'.

The movements of the Ganges River dolphin follow seasonal patterns, although the details are not well known. However, it seems that animals travel upstream when water level rises, and from there enter smaller streams.

Size
Females are larger than males and attain a maximum size of 2.67 m. Males are about 2.12 m.

Colour
The colour of the dolphin is greyish brown. The calves and young ones are dark in colour but as the animal grows in size, the colour lightens.

Habitat

Major habitat type
Ganga and Brahmaputra river system

Biogeographic realm

Range States
Nepal, India, Bangladesh

Geographical Location
South Asia

Why is this species important?

The presence of dolphin in a river system signals a healthy ecosystem. Since the river dolphin is at the apex of the aquatic food chain, its presence in adequate numbers symbolizes greater biodiversity in the river system and helps keep the ecosystem in balance.

Endemism

Ganges, Brahmaputra, and Meghna river systems

Interesting Facts

The dolphin's vision has probably degenerated because of the poor visibility of the waters in the Ganges River.