Irrawaddy dolphin

The Irrawaddy dolphin exists in small isolated populations around Southeast Asia. Some populations are close to extinction such as the those in the Mekong River and Malampaya Sound in the Philippines. The main threats are from fisheries bycatch and habitat loss.
Irrawaddy dolphin with head above water, Kalimantan (Borneo), Indonesia.  rel=
Irrawaddy dolphin with head above water, Kalimantan (Borneo), Indonesia.
© WWF-Canon / Alain COMPOST








 

Key Facts

  • Common Name

    Irrawaddy dolphin, orcelle (Fr), delfín de Irrawaddy (Sp)

  • Scientific Name

    Orcaella brevirostris

  • Status

    Vulnerable

    Read more

  • Length

    180-275 cm

  • Skin colour

    Slaty blue to slaty gray

Patchy distribution for a vulnerable species

The species is primarily found in Southeast Asian estuaries and mangrove areas, with freshwater populations occurring in river systems.

The Mahakam river population of Irrawaddy dolphins, found in the Kalimantan province of Indonesian Borneo, is severely threatened by fisheries bycatch and habitat degradation, and may number as few as 34 animals.

Surveys conducted in 2001 estimated that the Malampaya Sound population in the Philippines consists of just 77 individuals, confined to a small area in the inner sound, and is the only known population of this species in the country.

During 2001 there were reports that as many as five animals from this population were killed incidentally in fishing operations, indicating that the Irrawaddy dolphins of Malampaya Sound are in immediate danger of extinction due to low numbers, limited range, and high mortality.

The Mekong River Irrawaddy dolphin (Orcaella brevirostris) population inhabits a 190km stretch of the Mekong River between Cambodia and Lao PDR. The latest population is estimated between 78 and 91.
 / ©: WWF Greater Mekong
The critically endangered Mekong River Irrawaddy dolphin.
© WWF Greater Mekong

Physical Description

The Irrawaddy dolphin is identified by a bulging forehead, a short beak, and 12-19 teeth on each side of each jaw. The pectoral fin is broadly triangular. There is a small dorsal fin, on the posterior end of the back.

When diving, this dolphin breathes at intervals of 70-150 seconds; the head appears first and then disappears, and then the back emerges, but the tail is rarely seen.

Size
Head and body length is 180-275 cm.

Colour
Irrawaddy dophins are slaty blue to slaty gray throughout, with the underparts slightly paler.

Priority species

Cetaceans (whales, dolphins, and porpoises) are a priority species. WWF treats priority species as one of the most ecologically, economically and/or culturally important species on our planet. And so we are working to ensure such species can live and thrive in their natural habitats.

Ecology and Habitat

An inhabitant of marine and freshwater environments

Irrawaddy dolphins are distributed in shallow, near-shore tropical and subtropical marine waters. They are primarily found in estuaries and semi-enclosed water bodies such as bays and sounds, usually close to mangrove forests. Freshwater populations occur in river systems.

Social Structure

There are no more than 10 animals to a group usually, and solitary individuals are rarely seen.

Diet

The species eats fish and crustaceans.

Population and Distribution

Small populations over a large area

Current population and distribution

Freshwater subpopulations occur in the river Mahakam of Kalimantan (Indonesian Borneo), the Ayeyarwady (formerly Irrawaddy) of Myanmar (formerly Burma), and the Mekong Delta of Laos, Cambodia, and Vietnam. They are also reported in isolated brackish (saltwater and freshwater) water bodies, such as Chilka Lake in India and Songkhla Lake in Thailand.

There have been serious population declines in parts of Thailand, and in the Mahakam river (Indonesian Borneo) freshwater sub-populations. The latter was classified as Critically Endangered in the IUCN Red List in 2000 after surveys found only a few tens of dolphins in approximately 300 km segment of a river.

In the Philippines, the few Irrawaddy dolphins of Malampaya Sound (Palawan) appear to be geographically isolated from other sub-populations, which could earn that population the status of Critically Endangered. There, the dolphin population is in immediate danger of extirpation due to low numbers, limited range and high mortality. A 2001 survey put their population at 77 individuals over a 133 km² area.

Geographical Location
Southeast Asia

Range States
Indonesia, India, Thailand, Myanmar, Laos, Cambodia, Vietnam, Philippines


Population numbers

  • Malampaya Sound, Philippines: 77
  • Mekong River: 78-91
  • Mahakam River, Indonesia: 87
  • Ayeyarwady River, Myanmar: 58-72
  • Coastal waters of Bangladesh: 5,383
  • Sundarbans mangrove forest of Bangladesh: 451

What are the main threats to the Irrawaddy dolphin?

Unexploited but vulnerable

Although the Irrawaddy dolphin is not directly exploited, it is exposed to incidental mortality in fisheries (e.g., gillnets in Australia and in Malampaya, explosives), the principal cause of depletion. Habitat degradation due to development of dams, deforestation and mining also continue to undermine the species to a lesser extent.

The small population of the Mahakam River (Indonesian Borneo) and possibly that of the Ayeyarwady River (Myanmar) are also live-captured for display purposes.
 / ©: WWF-Canon / WWF-Cambodia
Mekong River Irrawaddy dolphin (Orcaella brevirostris) found dead in Cambodia.
© WWF-Canon / WWF-Cambodia

What is WWF doing?

WWF works with the Cambodian government's Department of Fisheries to implement the Cambodian Mekong Dolphin Conservation Strategy.

WWF is also helping Cambodia and Lao PDR to coordinate their conservation efforts. Key elements of the work include raising public awareness, development of relevant laws, responsible tourism, and Irrawaddy dolphin research.

WWF initiated the Malampaya Sound Research and Conservation Project in the Philippines in December 2001 to sustainably manage the fisheries of Malampaya Sound and to effectively manage and protect the Irrawaddy dolphin population in the area. Malampaya Sound, to date, is the only known habitat of the Irrawaddy dolphin in the country.

In 2004, WWF and TRAFFIC supported a ban on the international live trade of Irrawaddy dolphins for oceanaria by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

The majority of WWF's global conservation work to protect whales and dolphins takes place within the context of the International Whaling Commission (IWC).

WWF projects that support this work:

 / ©: WWF Greater Mekong
Cambodian students learned about Irrawaddy dolphin conservation in the Mekong.
© WWF Greater Mekong

How you can help

  • Support efforts to improve fishing gear by only buying seafood that is MSC certified. This can help to reduce the incidence of marine bycatch, which kills whales and other marine life like turtles, dolphins, and seabirds.
     
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Did you know?

    • Reports from the 1970s show that the fishermen of Burma attract the Irrawaddy dolphin by tapping the sides of their boats with oars. By swimming around the boat, the dolphin brings the fish into nets, and the fishermen share their catch with it.

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