Freshwater Irrawaddy Dolphins

Population size: Irrawaddy dolphins have a patchy coastal marine and freshwater distribution in tropical and sub-tropical waters of the Indo-Pacific, from northern Australia in the south to the Philippines in the north, and west to north-eastern India. However, freshwater populations of Irrawaddy dolphins are among some of the most threatened cetacean populations in the world. Although they are currently viewed as one species, future evidence may demonstrate that these freshwater populations are discrete subspecies. If that is the case, currently, the freshwater populations found in the upper reaches of the Mekong in Cambodia and Laos, number less than 100, even as few as 40. The population found in the Mahakam River and associated lake systems in East Kalimantan are data deficient but the numbers are thought to be very small. The population found in the freshwater Songkhla Lake in Southern Thailand showed a dangerously low population, perhaps as low as tens or twenties estimated from sightings made in 2001. The population found in the Ayayarwady River (formerly the Irrawaddy, from where the dolphins get their name) in Myanmar was recently estimated by researchers as only a few tens and was assessed as critically threatened with extinction.

Distribution: As above. Recent surveys have demonstrated a rapid decline in the populations of Irrawaddy dolphins and as a consequence they have been upgraded to CITES Appendix 1 and classified as critically endangered by IUCN World Conservation Union on the Red list in 2000.

Threats: Gillnetting and fish traps as well as entanglement in fishing lines, electrofishing, collision with boats, over fishing, dynamiting, damming projects, industrial and agricultural developments, pollution events notably through open cast mining activities using heavy metals such as mercury and degradation of both riverside and river environments.

Interesting Facts: The Irrawaddy dolphin is a charismatic species that has a short snout and a bulbous melon and travels in small groups, usually around 6 but up to 15. The dolphins usually keep a low profile in the water, having virtually no dorsal fin but are known to occasionally spyhop, breach and make low-angle leaps.