India’s largest brackish water lake is home to their highest single lagoon population

Odisha Forest Department officials, wildlife experts and researchers on Sunday sighted 146 endangered Irrawaddy dolphins in Chilika Lake, which boasts of the highest single lagoon population of the aquatic mammal in the world.

The dolphin census was simultaneously taken up in Chilika and off Odisha coast. The Chilika Development Authority (CDA) is elated that the direct sighting of 146 dolphins meant that its population in the lake would stabilise well above 150. According to last year’s census, the Irrawaddy dolphin population in Chilika was 151.

‘Direct sighting’

“The direct sighting of 146 dolphins only corroborates the estimate of the CDA, which does counting of dolphins round the year using hydrophones. Our estimated population range is 133-172,” said Susanta Nanda, Chief Executive Officer, CDA.

His confidence stemmed from the fact that dolphins were colonising new areas, which had been freed from encroachments by prawn farming gherries.

“We have noticed dolphin movements in new areas in the central and southern sectors, more specifically in the areas near Kalijai and Rambha. These areas were made free from encroachments,” said Mr. Nanda.

He expressed hopes that that the population is likely to increase in the next couple of years as there are enough signs of dolphins migrating from the Satpada side to other areas.

Hydrophone monitoring

According to hydrophone monitoring carried out round the year in Chilika, the highest number of Irrawaddy dolphins (20-25) was moving around Rajhans, followed by the Magarmukh and Malatikuda areas, where dolphins numbering between 17-20 were expected.

The total population of these aquatic mammals in the world is estimated to be less than 7,500. Of these, more than 6,000 Irrawaddy dolphins have been reported from Bangladesh, while the dolphin distribution in Chilika is considered to be the highest single lagoon population.

The wildlife wing of the State Forest and Environment Department would provide a more precise number of the adult and calf population of Irrawaddy dolphins after detailed analysis.

According to the CDA, the water-spread area of Chilika varies between 1,165 to 900 sq. km. during the monsoon and summer respectively, making it the largest brackish water lake in the country.