Gangetic Dolphins Are Defying The Odds — Yet A Silent Trade Devours Them

As Sanjay Nishad rowed with the ease of someone who had spent a lifetime on the river, the the boat moved steadily over the Ganga, making its way back towards Vindhyavasini Ghat, not far from the Maa Vindhyavasini Temple in Vindhyachal. The water was calm, the occasional plastic wrapper floating by. Then, without warning, a dolphin surfaced—a quick, grey arc before vanishing again.

"Dekha babu? Bas ek jhalak, phir gayab. Eehi Ganga maiya ke leela baa—jis par kripa hoi, ohi ke darshan mili," Nishad quipped with a knowing smile. (Did you see it? Just a glimpse, then gone. This is Mother Ganga’s divine play—only those who have her grace get to witness it.)

That was 2015. A decade later, that fleeting glimpse of the Gangetic dolphin remains as much a reflection of its nature as of its reality in the river.

Surfacing for barely five seconds, only to disappear again, it is easy to miss. But its brief appearance is not just a matter of habit—it is also a silent metaphor for its existence in these waters, a quiet symbol of its endangered status.

It keeps slipping in and out of sight, much like the awareness of its plight itself.

The Ganga Puputaka 

The Gangetic Dolphin, often referred to as the "susu" by local river communities, is a subspecies of river dolphin found in the waters of the Ganga, Brahmaputra, and their tributaries across India, Nepal, and Bangladesh. It was first scientifically described in the 19th century by Scottish surgeon and botanist William Roxburgh, who named it Platanista gangetica in 1801. However, the susu has held a place in Indian culture for millennia, deeply embedded in local folklore and traditions along the Ganga.

Beyond its cultural significance, the Gangetic dolphin is a highly specialised species, perfectly adapted to life in the river. Essentially blind, it relies on echolocation to navigate the silt-laden waters of the river and its tributaries. By emitting high-frequency sound waves, it can detect objects and prey, with the returning echoes providing essential spatial information. Females, larger than the males, give birth to just one calf every two to three years, making their reproduction slow and their survival all the more fragile.

Due to its endangered status, the Gangetic Dolphin is protected under the Wildlife (Protection) Act, 1972, and has been listed on the International Union for Conservation of Nature Red List since 1996. In 2010, it was declared the National Aquatic Animal of India.

For decades, understanding of dolphin distribution, population, and the environmental factors affecting them was as elusive as the dolphins themselves. Most available data came from studies focused on small, isolated areas and short time frames, leaving significant gaps in the overall knowledge of the species. However, this is changing with a recent comprehensive survey conducted by the Wildlife Institute of India (WII).

Findings of the survey

Between 2021 and 2023, the Wildlife Institute of India (WII) surveyed 8,507 kilometres of rivers under Project Dolphin, delivering the first comprehensive count of India’s river dolphins.

The report records 6,324 Gangetic dolphins across the Ganga and Brahmaputra systems (range: 5,977–6,688). Of the total, 5,689 dolphins live in the Ganga system—3,275 in the main channel and 2,414 in tributaries—while the Brahmaputra system has 635.

This extensive effort across eight states fills a long-standing data gap by providing a detailed dolphin count—where earlier only rough estimates existed—after surveying 58 rivers, 28 by boat and 30 from the banks to account for seasonal changes.

A more optimistic picture than before

The numbers returned by the 2021–23 survey paint a more optimistic picture of the Gangetic dolphin population than those reported in previous decades.

Historically, estimates suggested a steep decline.

For decades, estimates of the Gangetic dolphin population have varied widely due to limited surveys and inconsistent data. In the 1980s and 1990s, figures ranged between 4,000 and 5,000, largely based on anecdotal reports and scattered observations. By the early 2000s, a more targeted survey recorded a sharp decline to around 1,800 dolphins along the Ganga and a few key tributaries, sounding early alarms.

Estimates have continued to vary in recent years, with the number put at approximately 3,500 in 2014 and rising to around 4,500 by 2022.

But WII’s 2021–23 survey marks a turning point, putting the population at 6,324—nearly double the previous high and more than triple the early 2000s low.

Consider the stretch of the Ganga between the Bijnor Barrage and the Narora Barrage. In 2010, a study recorded 56 dolphins along this 165 km section. Fourteen years later, the WII survey covering 183 km estimated 114 dolphins (with a range of 103 to 125), reporting a minimum count of 85 and an encounter rate of 0.6 dolphins per kilometre. The WII findings point to a notable increase in dolphin numbers over the past decade and a half.

However, a direct comparison between the new numbers and past estimates is not straightforward.

Methodologies have evolved significantly: earlier studies relied on visual counts, often in isolated patches and at varying times, prone to observer and availability biases. The 2021–23 survey, covering 8,507 km synchronously, used dual visual-acoustic methods, correcting for dolphins missed underwater (submerged 107 ± 46.8 seconds vs. surfacing 1.26 ± 0.23 seconds).

Scope, too, differs—past efforts rarely spanned the full range, omitting key tributaries like the Kosi. Seasonal timing, observer training, and boat speed consistency further refine the new data, unlike the ad-hoc approaches.

"Until now, dolphin population estimates were based on multiple survey methodologies that did not fully correct for these biases. Previous surveys were partial, covering only specific dolphin habitats rather than the entire range," explains Dr Vishnupriya Kolipakam of the WII, who led the project along with Professor Qamar Qureshi.

"In contrast, the current survey followed standardised protocols, conducted during the same season across the entire range of the river dolphin in India. In addition to the primary survey, secondary surveys were carried out to verify historical ranges, assess seasonal movements, and identify resident populations," she told Swarajya, adding, "Since this is the first comprehensive survey covering the dolphin’s full range in India, it is not yet possible to determine whether the population is increasing or decreasing."

Since there has never been a full-range, standardised survey like this before, scientists lack a consistent baseline to compare the current numbers with. 

However, the data from the new survey, Dr Kolipakam told Swarajya, "suggests the population remains stable in the main river channels."

This means that while the survey cannot confirm whether dolphin numbers are increasing or decreasing overall, it does offer a reassuring sign: in the primary habitats of the Gangetic dolphins, namely the main river channels, the population does not appear to be in decline, contrary to what in often believed. Stability here suggests that these core areas continue to support viable dolphin populations, which is an encouraging sign.

The Ganga’s stretch between Kanpur and Varanasi is perhaps the river’s most polluted zone. This stretch also bears the weight of heavy urbanisation, its flow carved up by bridges and barrages, like the Kanpur Barrage, and dotted with sacred sites drawing millions, such as the Vindhyavasini Temple in Vindhyachal and Varanasi’s Assi Ghat. And yet, it cradles a hefty share of the dolphin population.

The WII's survey between Kanpur Barrage to Vindhyachal, covering 380 kilometres, tallied 718 dolphins, with an encounter rate of 1.9 per kilometre. From Vindhyachal to Chausa, spanning 260 kilometres, the count reached 334, with an encounter rate of 1.3 per kilometre. With an average depth ranging from 5 to 8 meters, this stretch holds firm, proving the river can still nurture its dolphins, even in its most battered reaches.

This is significant because dolphins sit at the top of the freshwater food chain and rely on an abundance of fish and other aquatic life to survive. Their presence in large numbers suggests that, despite the visible degradation, the underlying ecology—fish populations, water flow, oxygen levels—is still functional. In other words, if the dolphin is managing to live here, the river’s ecosystem is not beyond saving.

But conservation remains tricky

Across the Ganga and its tributaries, folklore among river communities has evolved into a quiet conservation mechanism, shielding the Gangetic dolphin from harm through tales tied to reverence and fear.

In Assam’s Mising community along the Brahmaputra, a story persists of Yakashi, a woman cast into the river for her clumsiness, only to transform into a dolphin instead of drowning, as noted in local narratives. This tale, shared among the Mising, casts dolphins—known as “xihus”—as kin reborn, fostering a taboo against killing them, a belief that has held for hundreds of years.

From the Nishads’ reverence for the dolphin to the Mising community’s belief in it as kin, such traditions and folklore are common across communities along the Ganga and Brahmaputra.

Yet, another reality coexists with these beliefs.

There have been at least 500 known Gangetic dolphin mortalities since the 1980s, the WII report says. And this number could just be much larger, if not the tip of the iceberg. Many of these deaths tie back to intentional killing, a practice that has eased with laws and awareness but still echoes in some areas, and more concerningly, as bycatch.

Studies suggest that around four to five per cent of the global population (found in India, Nepal, and Bangladesh) of Ganges river dolphins may be dying each year due to entanglement in fishing nets, a report by the Wildlife Conservation Trust (WCT) says.

According to Dr Nachiket Kelkar, Head of the Riverine Ecosystems programme at WCT, this mortality rate exceeds the species’ Potential Biological Removal (PBR) threshold—the maximum number of individuals that can be removed from a population (due to human activities) without affecting its long-term sustainability. In simple terms, more Gangetic dolphins may be dying in India, Nepal, and Bangladesh as bycatch than the population can naturally replace, putting the species at serious risk.

Gill nets, cast for fish, trap dolphins too. The use of large-meshed nylon and polythene monofilament nets significantly increases the risk of dolphin bycatch.

Dr Kolipakam calls it the "greatest threat to the species, which not only leads to accidental deaths but also indirectly contributes to dolphin poaching for oil used in bait fishing."

Fishermen have little incentive to report dolphin bycatch—under India’s Wildlife (Protection) Act, 1972, accidental entanglement is penalised just like intentional hunting. Given how lucrative the dolphin oil trade is, many choose to stay silent and cash in on their bycatch, rather than risk fines and legal trouble.

The dolphin oil trade compounds the problem.

Fishing communities across the Gangetic plains, from Bihar to West Bengal and Assam, have relied on oil-baits like fish extracts for generations. The use of dolphin oil in fishing, primarily for two species of freshwater catfishes—Eutropiichthys vacha (basha) and Clupisoma garua (ghaora)—probably started when fishermen saw these fish flock to dolphin carcasses, drawn by the decaying fat’s strong scent.

The process is straightforward: dolphins are killed, their blubber boiled to extract oil, producing 2 to 3 liters per animal, as Professor R K Sinha of Patna University, often referred to as the 'Dolphin Man of India', detailed in his 2002 study.

Traders in Malda commonly obtain dolphin blubber from Bihar’s Sahibganj, Udhwa, and Rajmahal regions, situated in the Kosi-Ganga floodplain. The blubber is matured in barrels before being transformed into oil and sold locally, forming a supply network that connects the two states. A striking example of this trade’s scope occurred in 2010, when Patna police seized over 20 kilograms of dolphin oil near Gandhi Ghat, a haul valued at thousands of rupees.

Beyond its use in fishing, the oil is also utilised in the region as a home remedy for joint pain, burns, and other ailments, increasing its demand. Moreover, dolphin meat is also consumed by some and it is sold at around Rs 150 – Rs 200 per kg.

A dolphin snared in a net becomes oil worth thousands. This incentive keeps the trade flowing, accidental catches blending seamlessly into the same jars as poached ones.

While intentional killings have declined, bycatch continues to sustain this market.

In 2020, researchers, including Dr Kolipakam of WII, conducted a study during which fish bait oil samples were collected from villages in Assam and West Bengal. The tests revealed Gangetic dolphin DNA in several samples, confirming the oil's use.

A survey of fishermen conducted as part of the study revealed that many knew the law, with 64.6 per cent aware that using river dolphin oil was illegal, yet they still used it for bait fishing. Among those who had seen dolphins caught in their nets, 57.8 per cent admitted to selling the carcasses for oil. When asked about other oils, 61.9 per cent said they had tried these substitutes for fishing, but they still viewed dolphin oil as more effective for catching catfish, highlighting the trade’s hold across these regions.

An effort to tackle the oil trade kicked off in 2007, led by the Noida-based Wildlife Trust of India along with Professor Sinha. They introduced a new oil from waste scraps of other fishes, especially from rohu, catla, and mrigal, priced at Rs 10 to 15 per liter, a substitute that those involved in the project claim proved just as effective at luring hilsa in tests.

Dolphin oil was still selling in Hooghly and Howrah, the same region where alternatives had been offered, proving the trade remains alive and kicking.

“There is certainly a supply chain. If you go to some of these villages, especially near the Bangladesh border in Murshidabad, and ask for dolphin oil, someone will direct you to a house where it’s stored,” Meghna Banerjee, Chief Executive Officer of HEAL, told Swarajya.

She recounted how undercover teams from HEAL discovered substantial quantities of dolphin oil being aged in villages, where access was granted with relative ease—highlighting the open nature of the dolphin oil trade in the region.

Banerjee also explained the complex nature of dolphin bycatch, saying it occurs in two forms. In some cases, it is non-intentional—as she noted, “when the dolphin gets stuck in the net,” meaning the catch happens accidentally and isn’t actively pursued.

However, in many instances, she says, it is done intentionally.

“They [fishermen] see that an animal has got stuck and instead of releasing it, they let it die and suffocate and then take it onto the boat and then cut it into pieces," she says.

While the trade is primarily local and carried out by fisherfolk, Banerjee noted that a nexus appears to be at work in districts like Malda and Murshidabad, with individuals involved in the oil trade potentially linked to networks extending into Bihar and Assam.

“Arrests have happened—I think two or three arrests happened between 2019 and 21—but that was only after we intervened and provided evidence of what we saw in that person's house,” she revealed. In her view, the authorities' response amounted to nothing more than “very minimal awareness programs,” a token effort that barely scratches the surface of a deeply entrenched illegal trade.

Sluggish and indifferent enforcement, Banerjee argued, has quietly allowed the oil trade to flourish, leaving the dolphin's fate in the hands of those who cast the nets.

Folklore, alone, can only guards the dolphin’s spirit.