<img class="styles__noscript__2rw2y" src="https://s.w-x.co/util/image/w/in-dolphinn%20%281%29.jpg?v=at&w=485&h=273" srcset="https://s.w-x.co/util/image/w/in-dolphinn%20%281%29.jpg?v=at&w=485&h=273 400w, https://s.w-x.co/util/image/w/in-dolphinn%20%281%29.jpg?v=ap&w=980&h=551 800w" > Representational image (Pixabay)

Odisha’s recent annual census of dolphins in its waters have thrown up some shocking numbers, with the aquatic mammals’ population declining from 469 in 2018 to 259 this year.

The census was carried out by the state’s forest and environment department on January 19 this year. The census report was released on February 14.

The census covered important aquatic ecosystems in the state including the Chilika lake, India’s largest brackish water lagoon, spread over the Puri, Khurda and Ganjam districts, the Gahirmatha Marine Sanctuary and its nearby areas within the Bhitarkanika National Park in Kendrapara district, Balasore district and the mouth of the Rushukulya river in Ganjam district.

“The 2019 dolphin census report revealed that Gahirmatha is the home of the state’s largest dolphin population, having 126 animals,” said Bimal Prasan Acharya, the divisional forest officer of Bhitarkanika National Park. “More dolphins were found in Gahirmatha than Chilika due to its bigger areas,” he added. But even 126 is a smaller number than the 307 sighted in 2018, said Acharya.

After Gahirmatha, Chilika had the next largest population at 113, followed by the Rushukulya river in Ganjam district, with 15 dolphins and finally, Balasore, with 5 individuals.

The dolphin species sighted during the state-wide census included the Irrawaddy, the Bottle Nose and the Humpback. The sighting of dolphins depended on the weather condition of the day the census was carried out, said Pradipta Kumar Sahoo, the deputy conservator of forests (wildlife management), Odisha.

The Irrawaddy dolphin is not a true river dolphin, but an oceanic one that lives in brackish water near coasts, river mouths and in estuaries. Across Odisha, 130 Irrawaddy dolphins were sighted on January 19, 2019. Out of these, 113 were sighted in Chilika, where 162 animals had been sighted last year and 123 in 2017. In Gahirmatha, 14 Irrawaddy dolphins were sighted. In Balasore district, 3 animals were sighted.

A total of 16 Bottle Nose dolphins were seen in Odisha. Out of these, 2 were sighted in Balasore and 14 in Gahirmatha.

The third species, the Humpback, totalled around 113 animals of which 98 were sighted in Gahirmatha and 15 in Ganjam.

Dolphins have been included in Schedule I of the Indian Wild Life (Protection) Act 1972, in Appendix I of the Convention on International Trade in Endangered Species (CITES), in Appendix II of the Convention on Migratory Species (CMS) and categorised as ‘Endangered’ on the International Union for the Conservation of Nature's (IUCN) Red List.

“The reduction in the number of dolphins compared to last year could be due to the migration of species from the Chilika lake and other water bodies to the deep sea,” said Lala Aswini Kumar Singh, a former wildlife researcher of the Odisha forest department.

“Forest officials conduct dolphin censuses in the sea at a distance of only 10 kilometres from the coast as it is not possible for us to count dolphins in the deep sea. Climate change and bad weather may be also the reasons for the dolphins to migrate towards the deep sea. Death is not the reason behind the decline in numbers as only a few carcasses of dolphins washed ashore on the state’s beaches,” he added.

This story was originally published in www.downtoearth.org.in