Meet the Irrawaddy Dolphin
Neptune's Note V
Name: Irrawaddy dolphins are named after the Myanmar river in which they live, known in Burmese as the Ayeyarwady River. Their river residence means they’re sometimes referred to as the Irrawaddy river dolphin.
Family: One of almost forty extant dolphin species in the Delphinidae family.
Genus: The Orcaella was a singular genus including only the Irrawaddy dolphin until 2005 when a supposed Irrawaddy was confirmed to be a completely new species - the Australian snubfin dolphin - splitting the genus into two different species.
Location: They are found in dispersed subpopulations near coastal areas in South and Southeast Asia, including in three rivers, the Ayeyarwady, the Mahakam, and the Mekong. The latter of which once saw Irrawaddy inhabitants swimming along a 118 mile stretch between Cambodia and Laos. However, in 2022 the last Irrawaddy dolphin in this transboundary area became entangled in fishing gear and died, marking the extinction of the Laos subspecies.
Population: Numbers differ but recent surveys suggest there are less than 92 individuals left.
Status: Threatened mainly by bycatch and drowning in fishing gear, the IUCN lists five of the seven subspecies of Irrawaddy dolphins as endangered. They are also one of only six species of river dolphins left in the world today - all of which are endangered or critically endangered. River dolphins face many anthropogenic threats as their habitats are very close to human settlement.
Weight: 90-200kg
Length: Though they might appear quite little as their sweet small faces poke out of the water, they can actually grow to 9 feet (2.7 metres) in length.
Anatomy: Though they’re actually oceanic dolphins, the Irrawaddy’s tendency to inhabit rivers means they’re sometimes considered a part of the river dolphin species. If we accept that ruling then they are absolutely the cutest river dolphin species. With their bulbous foreheads and short beaks they look just like a baby beluga, though they’re not closely related. It’s this short beak that makes them easily distinguishable from other dolphins, as well as their moveable lips hiding 12-19 peg-like teeth and their flexible necks - making for a very friendly face! Their U-shaped blowhole is also unlike any other dolphin species as it opens towards the front of the dolphin as opposed to the back.
Diet: Irrawaddys will eat any type of fish that lives within their habitat range, including prey at the bottom of the river, estuary or coastal area. We know this as they’re sometimes spotted with muddy heads and backs! They’re also known to move in and out of river mouths with the tide, most likely following the movement of their prey.
Social habits: Irrawaddys are especially shy for a dolphin species as they keep clear of boats and don’t partake in bow-riding like most dolphins do. They will also dive if frightened (now tell me that doesn’t just add to their cuteness 😭). Usually found in groups of less than six individuals they communicate through clicks at a frequency of 60 kHz. This could also be used for echolocation as their melon-shaped head (similar to a beluga and sperm whale) would suggest. Known to spyhop, tail slap and wave their large flippers above the surface, they’re clearly very playful in their small groups, but rather timid.
Reproduction: The reproduction of the Irrawaddy dolphin is a no nonsense method as they spend several minutes pursuing a mate and just 40 seconds copulating. The gestation period lasts around 14 months and female dolphins will birth a single calf every 2-3 years which means repopulating the declining species can take some time.
Unique facts: Adding to their charm, the Irrawaddy dolphin can squirt streams of water over a metre into the air. It’s believed they use it to herd and confuse fish during hunting but also to expel the water ingested during eating.
What can be done to protect them: As a species inhabiting estuaries, river mouths and coastal waters, Irrawaddy dolphins are unfortunately very exposed to human activities. Their main threat comes from fishing gear as all subpopulations are at risk of drowning in gillnets, crab nets or dragnets as bycatch. They are also at risk from electrofishing, gold mining, dam building, and noise pollution from high-speed vessels in Myanmar waters. Their current status as an endangered species is bleak but there are those who are hard at work to protect the Irrawaddy dolphin. Every year Endangered Species International trains hundreds of Southeast Asian fishermen in monitoring and protecting the species to reduce bycatch. Promoting sustainable fishing practices and defining no-take zones will prevent further decline of the Irrawaddy by reducing the overfishing of their food source. As seen in the Sundarbans mangrove forest of Bangladesh where 539 square miles have been turned into three separate wildlife sanctuaries - an area which includes Irrawaddy dolphin habitat - the overall protection of natural ocean and river habitats must be established to protect this endangered species from a growing list of threats.
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Amie 🐋
What an adorable species 🥹 it’s horrific to imagine them getting caught up in fishing gear 😢 as you say, just more reason to create protected marine areas!