Irrawaddy Dolphin
Orcella brevirostris
Lifespan: ~30 years
IUCN: Endangered in coastal waters, freshwater regions critically endangered
All About O.brevirostris
Distribution
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Throughout South East Asia in sheltered coastal waters eg. estuaries, mangroves and deltas
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5 isolated freshwater populations: Myanmar, Borneo, Lao and Cambodia (Mekong), India, Thailand
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Whilst not described as a river dolphin, there are isolated freshwater populations hundreds of miles from the coastline
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Click here to see distribution research conducted by KOL
Description
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Max size: adult males up to 280cm (130kg), newborns up to 100cm (10kg)
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Beakless with blunt-rounded heads
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Flexible necks leaving obvious neck creases and a straight mouth line with movable lips giving the appearance of a smile
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Slate-grey colour with a paler underside producing a bipartite pattern
Behaviour and Ecology
Usually seen travelling in groups of 2-3 but occasionally reach up to 15 individuals
Diet consists of fish, shrimp and cephalopods hunted in shallow water
Very social but not very active at surface; can occasionally be seen low breaching
Spit water to potentially confuse fish during hunting
Myanmar population fish cooperatively with local fishermen by herding fish towards the boat - dolphins pick off the weaker individuals and those that are trapped around the outskirts of the net before the fishermen retrieve their nets
Main Threats
Habitat Loss
Damming affects the freshwater populations as they become isolated and confined to smaller areas which means reduced hunting opportunity
They are now restricted to 40% of their original range
Coastal populations are also affected by dams as they reduce the flow into estuaries and mangroves
Bycatch
​Arguably the biggest threat to Irrawaddy dolphins as they get entangled in small scale gillnets - this has always been the biggest reason for premature death and is increasing every year
Click here to learn more about our
Captivity
Irrawaddy dolphins are attractive to aquaria as they are relatively easy to catch using small fishing boats
Individuals have been taken from Cambodia, Myanmar, Indonesia, Vietnam and Thailand in the past
A ban on international commercial trade (CITES) came into effect in 2004 which stopped the capture of wild specimens of Irrawaddy dolphins
Pollution
Industrial and domestic waste enters the rivers resulting in high levels of water contaminants in both freshwater and coastal habitats
Six populations have been recorded to have skin abnormalities likely associated with high levels of water pollution
the unknown!
Specific threats to marine mammals in Cambodia is still relatively unknown; work is being done buy KOL to identify these threats and how we can mitigate them in the future​
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​​​Fun facts
Named after the Ayeyarwady River in Myanmar, formerly known as the Irrawaddy River when Myanmar was Burma;
in the Sundarbans mangrove forest Irrawaddy Dolphins occupy the same habitat of ganges river dolphins
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Coastal Cambodian populations occupy the same space as Indo-pacific humpback dolphin and Indo-pacific finless porpoise
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Laotian and Cambodian folklore suggests Irrawaddy Dolphins to be reincarnations of their ancestors
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West Kalimantan people share stories of Irrawaddy Dolphins being naughty children that stole rice from the shaman, but they burnt their mouths and jumped into the river to cool down but transformed into Irrawaddy Dolphins
