Wildlife & Biodiversity

Dolphin population in Odisha's Gahirmatha halves: Annual census

Total 233 dolphins spotted across Odisha, down from 259 in 2019, 270 in 2015

By Ashis Senapati
Published: Tuesday 25 February 2020

An annual census found the number of dolphins at Odisha's Gahirmatha marine sanctuary has nearly halved over a year, pushing down the state's overall count.

The January 2020 census spotted only 62 of the marine mammals at Gahirmatha — also the world’s largest rookery of sea turtles — down from 126 found last year. Gahiramatha is located within Bhitarkanika National Park in Odisha’s Kendrapara district.

The state's total dolphin count was pegged at 233, down from 259 in 2019, according to census report released February 24, 2020. 

“During the day-long dolphin census on January 19, forest officials sighted 60 Irrawaddy dolphins and only two bottle-nose dolphins in Gahirmatha. In 2019, we sighted 14 Irrawaddy dolphins, 14 bottle-nose dolphins and 98 humpback dolphins,” said Pradipta Kumar Sahoo, deputy conservator of Odisha’s Forest (Wildlife Management).

Officials conducted a dolphin census for the first time in Gahirmatha in 2015. The census in 2016 and 2017 had been cancelled due to bad weather. The 2020 census was the fourth such dolphin census undertaken in the marine sanctuary.

The 2015 census recorded 270 dolphins.

“In 2015, during the first-ever dolphin census, we counted 58 Irrawaddy dolphins, 23 bottle-nose dolphins, 123 Sousa chinensis dolphins, 50 Sousa plumbera  dolphins, 15 pantropical spotted dolphins and one finless porpoise dolphin in the water bodies of Gahirmatha,” said Bikash Ranjan Dash, divisional forest officer at Bhitarkanika.

In December, carcasses of three Irrawaddy dolphins, including a calf, were washed ashore on the beach at Pentha within Gahirmatha.

Chilika lake, another biodiversity hotspot, also saw a spurt: “We sighted 146 Irrawaddy dolphins and 17 bottle-nose dolphins in Chilika. In 2019, we found only 130 Irrawaddy dolphins there.”

Chilika — spread across Puri, Khurda and Ganjam districts — had been designated a Ramsar site in 1981. A Ramsar site is a wetland site which comes under the Ramsar Convention of 1971 and allows for measures to conserve biodiversity in these areas.

“Two Irrawaddy dolphins and five bottle-nose dolphins were spotted near Puri. In Baleswar district, we counted only one bottle-nose dolphin,” he said.

In 2019, the Odisha High Court had ordered the state government to initiate the demolition of illegal prawn gherries in Chilika Lake to restore the wetland’s ecology.

Gherries are encroached areas used for illegal prawn cultivation inside wetland areas. Illegal prawn farming has choked Chilika’s biodiversity.

“Acting on the court’s order, we demolished around 162 square kilometers of illegal prawn gherries last year,” said Susant Nanda, chief executive of the Chilika Development Authority.

“Dolphins were earlier confined to the Satapada area of Chilika, a Ramsar site. But this year dolphins spread all across the lake because of large tracks of illegal prawn gherries being dismantled,” he added.

The dolphin has been included in Schedule I of the Indian Wildlife (Protection) Act 1972. The sea mammal is also included in Appendix I of the Convention on International Trade in Endangered Species and in Appendix II of the Convention on Migratory Species.

It is also categorised as endangered on the International Union for the Conservation of Nature's (IUCN) Red List.

Many dolphins die off the coast every year after getting caught in nets as a result of fishing and trawling activities. It is because of this reason why forest officials sighted few dolphins in Gahiramatha.

Seeing as many studies have shown the high intelligence of the dolphin, it is clear that these mammals are aware of such dangers. However, they are left with little choice due to their need to search for food around trawlers or boats, said Hemant Rout, secretary of non profit Gahiramatha Marine Turtle and Mangrove Conservation Society.

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