The Irrawaddy dolphin – September 2020

This little (2m – 2.8m / 6-9 feet) dolphin looks like a baby beluga whale. Irrawaddy dolphins (Orcaella brevirostris) have a super cute and expressive face. In this post, we list a couple of interesting facts about these shy and endangered dolphins.

1 — Small geographical range

Irrawaddy dolphins live in coastal areas in South and Southeast Asia. They also live in three rivers: the Ayeyarwady (Myanmar), the Mahakam (Indonesian Borneo), and the Mekong River. The Mekong Irrawaddy dolphins habitat consists of only 190 km (118 miles) of the Mekong River, northeast of Cambodia, and southwest of Laos. Their habitat has been greatly reduced after the construction of multiple dams on the Mekong river.

2 — Shy yet photogenic

Irrawaddy dolphins are quite shy and usually hide from boats. They can dive underwater and hold they breath up to 12 minutes but usually dive for short periods (under 1 min). Unlike other super charismatic species like spinner dolphins, they do not usually jump above the water or exhibit crazy behaviors. The same way, they do not swim really fast, are pretty sluggish and their record swimming speed is around 25 km/h (15 mph). Other reports mentioned that Irrawaddy dolphins get bullied by humpback dolphins in the Mekong river. They usually flee as soon as they get close to humpbacks… It seems that Irrawaddy dolphins are the underdogs of their environments. Yet, being shy does not mean they cannot look cute! Look at this face …

3 — Collaboration with fishermen

Burma’s (Myanmar) Irrawaddy dolphins collaborate with fishermen to catch fish. Experienced fishermen “call” the dolphins, drumming a wooden stick on their boats. The dolphins soon show up and help push the fish inside the nets. Fish is rarer and rarer in this part of the river and fishermen cannot afford to give part of their prize back to the dolphins. Yet, experts think that the dolphins are able to collect some fish within the nets and this might be the reason why they keep helping fishermen. This relationship is fragile and has suffered from shameless fishing activities. Some local fishermen, despite the regulations, still use electroshock fishing to catch whatever remains in the river. These same fishermen have electrocuted a couple of trusting Irrawaddy dolphins in the past. As a result, the angered dolphins are sometimes hesitant to collaborate with fishermen.

4 — An endangered species

The Irrawaddy dolphin was declared endangered in 2017 by the IUCN. With only 92 individuals remaining (compared to 200 individuals 20 years ago) in the most studied Mekong river area, the population faces risks of extinction. The main threats to their survival include bycatch in nylon gillnets, overfishing that depletes the Mekong river of its fish, boat traffic causing stress and collisions, dams that limit the size and quality of their habitat, and chemical pollution from pesticides, plastics, and heavy metals.

5 — Hope remains

With joint effort from the local authorities, residents, and NGOs like WWF, the Irrawaddy dolphin Mekong population has been stable since 2010. More calves are being born while fewer dolphins die annually. This is great news for these beautiful creatures. Ecotourism has helped both dolphins and local fishermen and conservation efforts must continue to make sure the population recovers. We still lack information from the populations in the other rivers and from the coast. Maybe this could be a fantastic opportunity if you are an aspiring marine mammalogist … The Irrawaddy dolphins need you!

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We hope you liked our post and learned a thing or two about Irrawaddy dolphins. Do not hesitate to share it to raise awareness of these mostly unknown dolphins. We would also like to warmly thank Anupam Koley for allowing us to use their photos on this post

Sources:

• IUCN Status
• WWF
• Fishermen collaboration
• International Whaling Commission
• Humpback dolphins and Irrawaddy dolphins interaction: Sinha, R.K., 2004. The Irrawaddy dolphins Orcaella brevirostris of Chilika Lagoon, India. Journal of the Bombay Natural History Society, 101(2), pp.244-251.