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In Search of the Irrawaddy Dolphin

The endangered Irrawaddy Dolphin is found in coastal and freshwater regions in Southeast Asia. Not much is known about these elusive marine mammals, and being able to spot them in their wild is a rare occurrence. Our contributors, Gargi Roy Chowdhury and Saurav Supakar, who are associated with the Wildlife Institute of India, report on their finding of the Irrawaddy Dolphin in the Hooghly River in West Bengal, with accompanying photographs by Rudra Chakraborty. 


In the May 2020 issue of the Journal of Threatened Taxa, there is an article on evidence of the presence of Irrawaddy Dolphin (Orcaella brevirostris) in river Hooghly of West Bengal. Just a day before the article was published, a newspaper report covered the rescue of a stranded Irrawaddy Dolphin, an aftermath of the cyclone Amphan in West Bengal, by the Ganga Prahris. The presence of this cetacean was a surprise to one of the respondents of the article.

Irrawaddy Dolphins are not true “river dolphins”, and are closely related to their oceanic counterparts. This euryhaline species resides in coasts, estuaries, or rivers along the Bay of Bengal and Southeast Asia. In India, it is found in the Chilka Lagoon in Odisha, it has also been reported from the coasts of Visakhapatnam. The Sundarban is one of the safe havens for this species. In West Bengal, this endangered species co-exists with another similarly endangered species, the Gangetic River Dolphin (Platanista gangetica). This is comparable to the Tucuxi (Sotalia sp.) and Boto (Inia geoffrensis) in the Amazon river.


Irrawaddy Dolphins sighted in the Sundarban Delta.

Image Credits (for all images): Rudra Chakraborty


The co-existence of the Irrawaddy and Gangetic dolphins also occurred in the Sundarbans, but a recent rise in the salinity level has led to an exodus of the Gangetic dolphins from the delta. Sparsely published newspaper articles and a handful of locals have reported the presence of the Irrawaddy Dolphin in the river Hooghly over the years. Interestingly enough, the presence of this species had missed the attention of the research community resulting in no mention of its presence in any scientific publication.

On the bank of the river lies the prominent metropolis of Kolkata. With the stress that the river faces in providing for the city, it is astonishing that there are these two magnificent species, among several others, that call this river home. More astonishing s the fact that one of these species had not yet been reported officially. Many species are being lost to us right under our noses; even before we are aware of them. Now that there is an official record, efforts should be made to re-examine our definition of the geographic occupancy of this species so that we could fill in the gaps in our knowledge and take better steps in formulating conservation measures.

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