Irrawaddy Dolphin, Chilika Lake

Vasanth Asokan
Irrawaddy dolphin in Chilika

Chosen as 'Picture of the Week'

Irrawaddy dolphins can grow to a length of 2.3 m and attain a weight of 130 kg. This species is closely related to the killer whale, a much larger, oceanic dolphin that can grow to 8m and weigh in excess of 6 tonnes.

This rare photograph captures an Irrawaddy dolphin calf as it leaps out of the water. Irrawaddy dolphins (Orcaella brevirostris) are quite shy, and all that can be seen of them most of the time is a dorsal fin or a tail fluke. They are believed to give birth to a single calf every two to three years, after a gestation of 14 months. A newborn is said to be 1 m long, weighing about 10 kg. As per available information, it is weaned in two years, reaches maturity when it is around 8 years of age, and could live up to 30 years.

Although the species gets its common name from the Irrawaddy River in Myanmar, where it also lives, it was first described in 1866 from a specimen found in the Vishakapatnam harbour in present day Andhra Pradesh on India’s east coast. Its range extends from the Bay of Bengal to New Guinea and the Philippines. Besides the Irrawaddy River, it is also found in India’s Ganges, and Southeast Asia’s Mekong River. However, it is not a true river dolphin and prefers to live in estuaries and brackish water near coasts. Following the opening of the sea mouth in Chilika in 2002, and the consequent increase in water depth, dolphins have reportedly been recorded in more areas of the lake than before, perhaps indicating an expansion of suitable habitat.

Irrawaddy dolphins are classified as ‘Vulnerable’ in the IUCN Red List of Threatened Species. In Chilika they can be seen singly, in pairs or as small groups of 4-6 individuals. They are fairly slow swimmers.

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Shekar Dattatri is a Chennai-based wildlife and conservation filmmaker.


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