Gangetic dolphin numbers plunge to 635 – Barak goes silent while Kopili sees first sighting

Syllad | The Rising MeghalayaMarch 5, 2025

Once thriving in Assam’s rivers, the endangered Gangetic river dolphin faces an uncertain future as numbers decline, with Barak losing its population entirely and Kopili recording a rare sighting for the first time.

According to the Gangetic River Dolphin Population Estimation report published by the Wildlife Institute of India (WII) on Wednesday, the distribution of these freshwater mammals remains concentrated in the Brahmaputra and its tributaries, including Subansiri, Kulsi, Beki, and Kopili. The count stands at 584 in the Brahmaputra, 22 in Subansiri, 20 in Kulsi, 4 in Beki, and 5 in Kopili.

The findings were unveiled by Prime Minister Narendra Modi during the 7th meeting of the National Board for Wildlife at Gir National Park. The survey covered 1,326 km of the Brahmaputra basin, yet not a single dolphin was found in the 124-km stretch of the Barak River from Sonabari (Assam-Manipur border) to Rajartila (Indo-Bangladesh border).

Interestingly, the dolphin population was 635 in the last population estimation conducted by the WII in 2012.

According to the report, Assam is ranked fourth in the country for dolphin population.

Barak: A lost habitat

The report suggests that the Gangetic dolphin underwent local extinction in the Barak River between the 1970s and 1980s. Historically, these dolphins thrived in the Barak and even ventured into the hilly river courses of Mizoram and Manipur. However, over time, their population became restricted to the Kushiyara River, a tributary of Barak, with resident dolphins now mostly found near the Indo-Bangladesh border.

Critical areas for conservation

The report identifies several key areas for dolphin conservation, including Kulsi River (Kamrup district), Subansiri River (Lakhimpur), Brahmaputra (Majuli, Guwahati, Goalpara-Bongaigaon, Dhubri), Dibru-Saikhowa National Park (Tinsukia) and Kaziranga and Orang National Parks.

With dolphin populations in Subansiri and Kulsi showing a worrying decline, conservation efforts in these critical habitats are deemed essential to ensure their survival.

Brahmaputra’s ecosystem holds hope

Despite the alarming drop in numbers, the Brahmaputra River remains a stronghold for the species, offering a diverse habitat with an average depth of 5.2 meters. However, tributaries such as Subansiri, Kulsi, Kopili, and Beki have significantly lower depths of 3.8m, 1.7m, 2.7m, and 1.7m respectively, which could impact dolphin survival.

The first-ever recording of Ganges river dolphins in the Kopili River during winter brings a glimmer of hope, suggesting possible range expansion or migration.

The bigger picture

The Brahmaputra’s morphological diversity not only sustains river dolphins but also plays a crucial role in supporting various aquatic species, including migratory waterfowl and resident aquatic birds. However, with a low dolphin encounter rate of 0.49%, urgent conservation measures are necessary to protect this iconic species from further decline.

As Assam grapples with the loss of its dolphin population in the Barak River, the focus now shifts to preserving the remaining strongholds and ensuring the survival of the Gangetic river dolphin, a keystone species of India’s freshwater ecosystems.