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The Irrawaddy dolphin (Orcaella brevirostiris) is found in coastal waters from the Bay of Bengal east to Palawan, Philippines and south to northern Australia. It also occurs in three large tropical river systems in Southeast Asia: the Mekong, Mahakam and Ayeyarwady.
The Irrawaddy dolphin is recognized by a bulging forehead, a short beak, and 12-19 teeth on each side of each jaw. The pectoral fin is triangular. 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 observed. It swims in a group of about ten animals, and solitary individuals are rarely seen.
As a euryhaline species, the Irrawaddy dolphin occurs in many types of aquatic habitats using freshwater and seawater environments. In rivers, it is found in relatively deep pools (10-50 meters) located at confluences or above and below rapids. In coastal waters, it commonly occurs in areas affected by freshwater inputs and may enter the lower reaches of rivers. It can also be observed many kilometers offshore and as far as 100 km upstream in river. In Malampaya Sound, Palawan, Philippines, most sightings of dolphins have been recorded in waters shallower than six meters.
Photo on the left: Irrawaddy dolphins. Photo on the right: Estuaries are important habitat for the Irrawaddy dolphin.
Populations of the Irrawaddy dolphin have been declining over the past 50 years and now the species is classified as Endangered. It is at risk of extinction throughout its range as a result of incidental catches and injuries, habitat degradation and destruction, and pollution. Wild populations are constrained by the species’ narrow habitat requirements (lagoons, estuaries, rivers, and lakes) and are therefore particularly vulnerable to the effects of human activities.
Water pollution pauses a significant risk for the Irrawaddy dolphin since it occupies aquatic habitats that are heavily contaminated with higher concentration of pesticides. For example, concentrations of organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) have been found in tissues of Irrawaddy dolphins collected in India. It is exposed to chemicals and sewage released from adjacent terrestrial activities. Noise and disturbance associated with construction, vessel traffic and military activities are features of everyday life for this species.
The Irrawaddy dolphin feeds on fish and crustaceans, and its food supply is highly threatened due to overfishing, the blocking of streams and the introduction of modem fishing implements. Therefore, maintaining healthy fish population and diversity is important to the Irrawaddy dolphin’s survival.
Overall protection from entanglement and other threats is either lacking entirely or largely ineffective. Without practical solutions, the decline of the Irrawaddy dolphin is bound to continue for the foreseeable future. However, Endangered Species International (ESI) aims with strength to save this majestic dolphin, restore its habitats, reduce water pollution where they live, and increase wild fish populations. We need passion, expertise, perseverance, and hard work, and ESI has it all.
Our passion and work to save the Irrawaddy dolphin
Overall, it has been a notable lack of on-the-ground conservation measures to protect remaining populations of the Irrawaddy dolphin. Flora and fauna along the rivers and estuaries, as well as local subsistence communities, are facing threats similar to those faced by Irrawaddy dolphins. Irrawaddy dolphin is therefore considered a flagship species for our freshwater and estuary biodiversity conservation activities.
Each year, Endangered Species International (ESI) trains 1,000 fishermen on monitoring and protecting the endangered Irrawaddy dolphin in Southeast Asia to avoid deadly bycash. ESI directly promotes sustainable fishing practices and no-fishing zones (no-take zones) in areas where dolphins are still found. Further, ESI focuses on restoring and protecting natural habitats like estuaries and rivers where dolphins occur. Finally, ESI works very closely with local communities and authorities to control and reduce water pollution.
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