Assam: Sand mining, over fishing and bridges lead to decline of river dolphins in Kulsi

Recovery of a Gangetic River Dolphin carcass near the construction site of a bridge on the Kulsi river in Assam's Kamrup district on June 12 has once again raised serious questions over the future of Kulsi’s last surviving dolphins. The carcass of the newborn river dolphin was retrieved by a team of forest personnel at the Kukurmara stretch of the Kulsi River in south Kamrup, about 25 km from Guwahati.

Postmortem reports revealed serious injury marks, possibly from accidental collision with pillars of the under construction bridge. “We examined the dead dolphin. It is just 92 cm in length, probably one or two-days old,” said Dr Abdul Wakid, project scientist, Wildlife Institute of India. “We observed both the internal and external injuries of the carcass and suspect it died from possible collision with bridge pillars.”

Similar incidents were reported from the area earlier. Last year two dolphin deaths were recorded from the area while the number of deaths was three in 2022. A report by Wildlife Institute of India has already warned of the possible dangers brought in by these bridges with the wide and tall pile caps constricting movements of the aquatic mammals.

“There are four bridges now including the railway ones (three completed and one under construction) in a limited area,” Dr Wakid said and added “for a river dolphin habitat like Kulsi, these bridges are constructed most unscientifically intervening with the water-flow regime of the river, fragmenting dolphin habitats and creating acoustic barriers for the blind mammals.”

Acoustic vision being the primary mode of perceiving the environment for these animals, increasing noise levels and industrial activities cause major disruption in their perception of biologically critical sounds. Scientists find conservation efforts of river dolphins in the Brahmaputra have largely ignored the aspect of Acoustic Habitat Degradation.

Rapidly decreasing numbers

Once, the most commonly sighted aquatic mega-fauna in the Brahmaputra, the Ganges River Dolphin (Platanista gangetica gangetica) now faces extirpation from most of the major tributaries of the Brahmaputra and restricted to a few pockets in the mainstream.

Unregulated rise in human activities is causing serious degradation in Ganges River Dolphin habitats in the Brahmaputra river system. Accidental deaths of dolphins, entanglement in fishing nets continue to worry conservationists.

Surveys undertaken in 2012 found 635 dolphins in the Brahmaputra. “It is the two tributaries of the Brahmaputra where the Ganges River Dolphin numbers plummeted,” said Dr Abdul Wakid. In Subansiri, the species face severe threats of extinction from the dams upstream while sand mining and other development activities make them all the more vulnerable in the Kulsi River. The Kulsi, some years back, was the only tributary to have hosted a healthy population of the species.

A comprehensive dolphin survey conducted earlier by Dr Wakid confirmed the existence of more than 200 in the Brahmaputra mainstream and some 50 more in the two tributaries -- the Subansiri and Kulsi (Kolohi). Kulsi was known as a safe haven for the river dolphins, thanks to the beliefs associated with these creatures. Locally known as Shishu, villagers consider killing of the blind aquatic creature as harbinger of bad luck.

Domukha, at the confluence of the Kulsi and the Batha rivers, housed more than 30 dolphins. However, overfishing, unregulated sand mining and other development activities led to the disappearance of Ganges River Dolphins from Domukha.

“Wetlands in the area would supply abundance of fish into the Kulsi on which the dolphins survive. However, with the transformation of agricultural lands and wetlands into industrial land banks the whole landscape has altered. Agricultural production declined rapidly. Further, waste disposal in the river by the industrial units and construction of walls in the river itself in Domukha jeopardized the existence of Kulsi dolphins” alleged a local youth.

There had also been a growing resentment among local people at the perceived unfairness their lands have been snatched away by a section of land mafias.

One of the channels of the Kulsi was blocked by the sand mining groups impeding the free movement of the endangered species; industrial units erected walls right in the heart of that stretch of the river where dolphin pods were seen frolicking.

Locals alleged that the river dolphin numbers were reduced to less than 20 in the last few years after start of construction of bridges on the river. The threat to their existence continues to loom large unless their habitats are secured.

Declared Assam’s State Aquatic Animal in 2008, the Ganges River Dolphin went on to become the National Aquatic Animal a year later. The Kamrup district administration voted the river dolphin as the City Animal of Guwahati. Unfortunately, the bid hardly yielded results in its conservation even in the Kamrup district!

MoEFCC projects failed to secure dolphin habitats in the Brahmaputra

The Ganges-Brahmaputra-Meghna and Karnaphuli River systems of India, Nepal and Bangladesh hosted a thriving population of the Ganges River Dolphin till some years ago. One of the four obligate river dolphin species of the world, Ganges River Dolphin numbers declined sharply over the years along with its range. The IUCN listed it as ‘endangered’ after the individual count estimated globally fall down to below 2000 in 1996. Because of its rapid decline, the species came to be categorized as a Schedule-1 Species in India under the Wildlife Protection Act, 1972.

A flagship species for the river ecosystem, river dolphin numbers indicate the health of the river.

The destruction of the river dolphin habitat in Kulsi continued when actually there had been an ongoing ‘Species Recovery Programme’ under the Ministry of Environment, Forest and Climate Change (MoEFCC).

The MoEFCC announced this major programme in 2016 for conservation of the Gangetic River Dolphin. The ‘Species Recovery Programme’, aimed at developing a recovery plan for the species and their habitats across the states of Assam, West Bengal, Bihar, Uttar Pradesh, Uttarakhand and Madhya Pradesh for the initial period of five years (2016-21) envisaged engagement of stakeholders in conservation of river ecosystems. In Assam, the conservation action plan focused on regular population monitoring of the species in the Brahmaputra and Barak Rivers and their tributaries and also factors affecting the species’ habitats.

However, questions are now being raised as to how the massive wall in the most unusual and critical patch of Domukha dolphin habitat had gone unnoticed even after constant monitoring of the species and its habitat. Domukha is devoid of dolphins now.

“You could hardly find any dolphin in the upstream of the Kulsi,” said a forest official on condition of anonymity. “Because of an altered water-flow regime in the Kulsi, the dolphins moved downstream. These animals prefer water that is at least five to eight feet deep and usually found in turbulent waters, where there are enough fish for them to feed on,” the official added.

“In the winter months there is hardly any water upstream. I found only three dolphins upstream--one among them pregnant. Unfortunately, the newborn has died from accidental collision with pillars of the bridge,” Dr Wakid confirmed.

The MoEFCC’s ‘Species Recovery Programme’ failed the dolphins in the Brahmaputra river system miserably. Even Project Dolphin, a Central Government initiative launched in 2021to conserve both riverine and oceanic dolphin species have failed to make any significant impact on conservation of the Ganges River Dolphin in Assam.

“The state forest department is solely responsible for factors affecting the species’ habitats in Kulsi—the most important stretch for the Gangetic River Dolphins in the Brahmaputra,” said Chandan Kumar Duarah, member of a Conservation NGO--Kaziranga Wildlife Society. “The issue of sand mining has long been overlooked that led to the decline of the Ganges River dolphins in Kulsi River,” he added.

Acknowledging the department’s apathy for the endangered species, Dr Abdul Wakid insisted that the Kulsi needs rejuvenation to ensure a sustainable water source. Indiscriminate sand mining and unchecked growth of industrial units must stop if we really want to save our State’s and also our National Aquatic Animal.

There is also a need to rethink the structure of bridge pillars. “We need to follow the example of Punjab’s wildlife preservation wing for their commendable work in protecting the Indus river dolphins and their natural habitat. A very small population of Indus river dolphin (Platanista gangetica minor), not even 10 individuals of these freshwater dolphin is found in river Beas and that particular stretch of the Beas in Punjab was declared a conservation reserve, with a ban on commercial fishing, netting or hunting,” he said.