Irrawaddy Dolphin

The Union Ministry of Environment, Forest and Climate Change (MoEFCC) has launched the second nationwide range-wide estimation of riverine and estuarine dolphins under Project Dolphin. For the first time, this survey includes the Irrawaddy dolphin population in the Sundarbans and Odisha, marking an important step toward comprehensive conservation planning.

About the Irrawaddy Dolphin

• Scientific Name: Orcaella brevirostris

• It is a euryhaline species of oceanic dolphin, meaning it can survive in freshwater, brackish water, and saltwater.

• The species is found in discontinuous subpopulations near sea coasts, estuaries, and rivers in parts of the Bay of Bengal and Southeast Asia.

Key Point: The Irrawaddy dolphin is uniquely adapted to thrive across varying salinity levels, unlike many other dolphin species.

Habitat and Distribution

• Found in three major rivers of South and Southeast Asia:

  • Irrawaddy River (Myanmar)

  • Mahakam River (Indonesia)

  • Mekong River (Cambodia)

• Presence in India:

  • Primarily found in Chilika Lake (Odisha)

  • Also reported in the Sundarbans region

• They prefer muddy, brackish waters near river mouths and deltas and typically do not venture far offshore.

Important Highlight: In India, Chilika Lake hosts a significant population of Irrawaddy dolphins.

Physical Features

• The dolphin has a rounded face and head with no beak, giving it a baby-like appearance.

• It has a small dorsal fin, long flippers with curved edges, and a large tail.

• The body is grey overall with a lighter belly.

• It possesses narrow, peg-like teeth (about 1 cm long) in both jaws.

• The species has movable lips and flexible neck creases, allowing head movement in all directions.

Distinctive Feature: The absence of a beak and rounded head make it instantly recognisable.

Conservation Status

• Classified as ‘Endangered’ under the IUCN Red List.

Major Threats Include:

• Habitat degradation

• Fishing net entanglement (bycatch)

• Water pollution

• Decline in river flow and ecosystem changes

Conclusion

The inclusion of the Irrawaddy dolphin in the nationwide dolphin population estimation under Project Dolphin represents a significant conservation milestone. Given its Endangered status and fragmented distribution, systematic monitoring and habitat protection are essential to ensure its long-term survival.