Irrawaddy Dolphin

Irrawaddy Dolphins Video
WCS researchers in Asia are studying a remarkable group of river dolphins, and offer an up-close view.
Irrawaddy Dolphin Photo
The recent discovery of six thousand Irrawaddy dolphins in Bangladesh increased hope for this endangered species.
©Alice Rocco

The small, beakless Irrawaddy dolphin frequents large rivers, estuaries, and freshwater lagoons in South and Southeast Asia. The Irrawaddy range extends from the Bay of Bengal to the Philippines and Papua New Guinea. Gray to dark slate blue in color, the dolphin has a rounded head and measures up to eight feet in length. Irrawaddy dolphins live in small groups of generally six or fewer, but sometimes as many as 15 individuals. They subsist on a diet of fish, and communicate with clicks, creaks, and buzzes. In a section of Myanmar’s Irrawaddy River, the dolphins are known to fish cooperatively with humans, herding fish schools toward the fishermen where they are easily caught in cast nets. The practice benefits the fishermen—increasing the size of their catches up to threefold—as well as the dolphins, which fill their own stomachs on the cornered fish and those that fall out of the fishing nets.

Like several other species of dolphins and porpoises in South and Southeast Asia, Irrawaddy dolphins are disappearing at a rapid rate. However, there are some hopeful signs. Recently, WCS researchers found nearly 6,000 Irrawaddy dolphins swimming in the Sundarbans mangrove forest of Bangladesh and adjacent waters of the Bay of Bengal. Previously, the largest known populations of the dolphin had numbered in the low hundreds. Conservation of this enigmatic mammal, which lives in both river and marine environments, will depend on devising and implementing sound solutions for replacing harmful fishing practices and halting or mitigating the impacts of habitat loss.

Fast Facts

Scientific NameOrcaella brevirostris
  • The Irrawaddy dolphin is closely related to the orca, also known as the killer whale.
  • The gestation period for this dolphin is 14 months.
  • The Irrawaddy dolphin is the only dolphin that spits water during feeding and socializing.


Irrawaddy dolphins are facing increasing threats to their survival. Surveys conducted by local scientists and WCS in Bangladesh revealed accidental killing in a drifting gillnet fishery for sharks, as well as habitat loss caused by declining freshwater supplies and sea-level rise resulting from global climate change. The population in this South Asian country’s Sundarbans mangrove forest must also cope with declining freshwater supplies, caused by upstream water diversion in India coupled with sea-level rise. The latter issue has been brought on by climate change. WCS researchers are currently studying the long-term effects of this phenomenon.

WCS Responds

WCS collaborates with local scientists to investigate the impacts of human activities on Irrawaddy dolphins and develop science-based and community-informed approaches for addressing threats such as bycatch, prey depletion, and habitat loss. WCS works with governments, local NGOs, and rural communities to implement effective conservation management that incorporates the needs of local residents.

Despite the enormity of threats facing Irrawaddy dolphins, a recent victory in the Irrawaddy River offers a glimmer of hope. In 2006, with WCS aid, the government of Myanmar established a protected area to safeguard a population of the dolphins and their unique cooperative fishing practices with local communities. Spanning a 43-mile length of the river, the protected area has raised public awareness of Irrawaddy dolphins and their role in the livelihoods of local fishermen.

In the Sundarbans of Bangladesh, where WCS made its astounding discovery, our scientists are collaborating closely with the Ministry of Environment and Forests on plans to establish a protected area network to secure the dolphin stronghold. We are also supporting sustainable fishing practices and helping to develop local ecotourism projects that benefit the region’s people and wildlife.

WCS has developed and published the Action Plan for the Conservation of Freshwater Populations of Irrawaddy Dolphins. This document serves as a template for addressing the conservation needs of the vulnerable species throughout South and Southeast Asia. 

WCS Projects

Dolphins of Bangladesh Confront Changing Waters

Climate change is having a profound effect on the Sundarbans of Bangladesh, one of the most important sanctuaries for tropical dolphins. As sea levels in the Bay of Bengal rise with global warming, critical wildlife habitat in the adjacent mangrove forests has shrunk.

From the Newsroom

Bangladesh Helps Threatened Dolphins Stay AfloatFebruary 14, 2012

The Government of Bangladesh declares three new wildlife sanctuaries for Ganges River and Irrawaddy dolphins. A WCS collaborative study with the Bangladesh Forest Department helped pinpoint the locations of the new protected areas.

Dolphins Get Their DayJanuary 19, 2011

WCS’s Bangladesh Cetacean Diversity Project promotes public awareness of two threatened dolphin species in the Sundarbans.

Dolphin DiscoveryApril 1, 2009

Nearly 6,000 Irrawaddy dolphins are alive and swimming in Bangladesh, according to new WCS research. Prior to this study, the largest known populations of Irrawaddy dolphins numbered in the low hundreds or less.

Looking for a Good Catch? Ask the Irrawaddy DolphinAugust 4, 2006

A novel partnership between fishermen of the Ayeyarwady River in Myanmar and an endangered river dolphin guarantees a good catch for the fishermen. By establishing a protected area along a stretch of the river, the government of Myanmar is helping to safeguard this unique cultural tradition.

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