The Proposal for a Concerted Action for the South Asian River Dolphin that was anchored by India and endorsed by parties of the Convention on Migratory Species (CMS) in 2020 identified bycatch as one of the leading threats faced by Ganges river dolphin across their range, calling for collaborative efforts to attempt to address the issue. WWF-India is working along with partners – including the West Bengal Forest Directorate and the Wildlife Institute of India – and fishing communities in West Bengal to test a novel technology that could potentially reduce Ganges river dolphin bycatch in gillnet fisheries.  Pinging True showcases some of the ground realities faced by freshwater fishers in the region, through the eyes of Shanta Rajbanshi – a traditional fisherman who is now actively participating in dolphin conservation efforts in the Hugli River system.

Shanta Rajbanshi, a resident of Naliapur – a small village on the banks of the Hugli, in Purbha Bardhaman district, West Bengal – has been a fisher for almost three decades. Each morning he cuts diagonally across the river in his diminutive tin craft, locally known as a dunga, to reach his fishing grounds on the opposite side. Freshwater fish resources play an important role in the lives of riparian communities, both as a source of protein and a primary or secondary source of income, and as such, almost everyone from Naliapur is or once was a fisher.

Fishers in the region, operate thin monofilament gillnets, known as “current” or Illish jaal – which were primarily designed to target the fabled Hilsa (Tenualosa ilisha) or Illish in Bengali. These nets once deployed, flow downstream with the current till they are eventually collected; similar in working mechanism to drift gillnets – their oceanic counterparts.

Over the years, Shanta Da has been a silent spectator to much change. He has seen the river shift its course, exposing sediment rich flats which are now used to cultivate jute – a wiry thin crop that lines the waterfront. He has witnessed fishing practices being forced to evolve, driven by an ever-decreasing number of fish. From the days of the abundance – where massive gillnets were once operated, targeting only the largest of freshwater species – to today, where his meagre daily catch accrued from a twenty-foot net is barely sufficient to feed his family of four. He has watched as local youth, once fishers themselves, poured out of his village and state in search of employment elsewhere. But through this perpetual state of flux, something that has remained a constant is the presence of Ganges river dolphins (Platanista gangetica). If anything, he believes that the frequency of his interactions with the species has increased manifold, almost as if there are more dolphins now – which contradicts everything that the latest research on these imperilled animals tells us. What then is responsible for this perceived increase in fisher-dolphin interactions?

“At one time there used to be enough fish for all of us.” Shanta Da tells me. “Now with dwindling fish stocks, because of the barrage upriver and more and more pollution entering the waterway, we’re directly competing with dolphins for whatever fish are left.”

Ganges river dolphins have evolved to a life in the highly turbid waters of the Ganges and Brahmaputra River systems and are functionally blind – relying entirely on echolocation to navigate and hunt. As such, dolphins are unable to “see” the nets, only detecting the frantic vibrations made by ensnared fish as they try to break free. Whether the dolphins have started to associate the smaller fishing crafts with food, or simply respond to the rapid movements of entangled fish, is open to speculation. But irrespective of the reason, there is no disputing the fact that dolphins do aggregate around crafts and nets, “stealing” fish from active gear.

I spent an evening observing this mother and calf following dungas, with the occasional fisherman returning dejectedly to show me the damage to his net – the result of a fish being pried away by a dolphin. This interaction has multiple socio-ecological consequences. From the loss of catch for fishers; to damage to fishing nets; and dolphins getting accidentally entangled in gear – it’s a scenario where there are no winners. While most fishers in West Bengal do attempt to release dolphins if caught, the animals usually die from shock or drown and many release attempts are unsuccessful.

“It’s largely the younger dolphins that get entangled” Shanta Da explains. “The adults are stronger and they manage to break free or cut their way out. There have been times when a calf gets caught and the mother circles the vessel endlessly. It truly is heart-breaking because these are extremely intelligent animals, which seem to understand family, much like we do … But how do we make this situation better? Fishing is a livelihood for many of us – a ban is not the answer.”

Since 2022, WWF-India along with partners are working closely with fishers like Shanta Da, to test pingers – dolphin exclusion devices which are attached directly to fishing nets. Pingers work by emitting randomized clicks, the acoustic equivalent of a neon billboard, which in theory should ensure that dolphins maintain a safe distance from active gear. While the project is still in the early stages, the results so far look promising. Based on the data collected and feedback from fishers participating in the trials, dolphins do seem to be giving a safe berth to the pinger-equipped nets.

Shanta Da deploys a net with a pinger attached as part of the study. The effectiveness of pingers is being ascertained by visually observing dolphin surfacing behaviour – how close to active pingers does an animal surface – and also from recording dolphin vocalizations using specialized hydrophones, called F Pods – which help paint a picture as to the number and proximity of animals around the experimental setup.

In India, the use of pingers is still relatively new – with the only previous trials having being undertaken by the Wildlife Institute of India in 2022. How effective pingers will be is something that only time and the results of these long-term studies will tell, but for now, they seem to be amongst the most promising solutions at our disposal to secure populations of the endangered Ganges river dolphin and the livelihoods of traditional fishers.

This map summarizes the work being undertaken on Ganges river dolphins in West Bengal. The project team has successfully completed river surveys to assess the population size and distribution of dolphins in the Hooghly and Roopnarayan rivers. Through these surveys, areas of high dolphin densities which overlapped with significant fisheries pressure were identified as possible sites for the pinger trials. Naliapur is one such site and the first of three long-term experiments.

This work is funded by a Darwin initiative project grant, with additional support from Fishtek Marine