Ganges River Dolphins Are Surviving in Bangladesh's Most Polluted Rivers
A closer look at the Buriganga, the Shitalakhya, and what the latest surveys actually say about the shushuk's fight to hold on around Dhaka.
- Meet the shushuk: Bangladesh's blind river dolphin
- What the Buriganga study actually found
- Zooming out: 2,307 dolphins across the country
- Where does the Shitalakhya fit in?
- How polluted are these rivers, really?
- How endangered is the species, exactly?
- What the law actually says
- A global emergency, not just a local one
- Why a blind dolphin in a dirty river matters
- What comes next
- Frequently asked questions
Something unlikely is living in the Buriganga. For decades the 29-kilometre river that runs along the southern edge of old Dhaka has been described, without much exaggeration, as biologically dead — a channel of untreated sewage, tannery runoff and industrial dye so degraded that its native fish all but disappeared. Yet a year-long study completed in mid-2024 and reported widely in September 2026 found roughly twenty Ganges river dolphins living, feeding and even breeding in that same stretch of water.
It is one of the more startling wildlife stories to come out of South Asia in recent memory, and it says as much about the resilience of an ancient species as it does about the condition of the rivers ringing Bangladesh's capital — the Buriganga, the Turag, the Balu, the Dhaleshwari, and the Shitalakhya. This piece walks through what the latest surveys actually found, what Bangladesh's national dolphin count looks like once you zoom out from Dhaka, and what current law and policy are, and are not, doing about it.
Meet the shushuk: Bangladesh's blind river dolphin
The Ganges river dolphin, Platanista gangetica gangetica, is known locally as shushuk. First described scientifically in 1801, it is one of only a handful of obligate freshwater dolphin species left on Earth — animals that never enter the sea and cannot survive in salt water. It is functionally blind; its eyes lack a lens and can only distinguish light from dark. Instead, it hunts entirely by echolocation, sending out ultrasonic clicks and reading the echoes that bounce back off fish, shrimp and the riverbed itself. In India, where the same species is called the "susu," it has been the national aquatic animal since 2009.
Shushuk favour a very particular kind of habitat: deep pools, the slow-swirling eddies that form downstream of river confluences, and the countercurrents around bridge pilings and mid-channel islands. These happen to be exactly the places where fishing pressure, boat traffic and pollution also concentrate — part of why the species has vanished from so much of its historic range across the Ganges-Brahmaputra-Meghna basin.
What the Buriganga study actually found
Between September 2023 and August 2024, researchers surveyed a 27-kilometre stretch of the Buriganga and published their results in the Journal of Asia-Pacific Biodiversity. They recorded roughly twenty dolphins spread across twenty-five identifiable "hotspots" along that short section of river. Average group size came out to 4.18 animals — noticeably higher than earlier counts from the same river — and calves made up close to 16 percent of all sightings, which the team took as evidence that the population is still reproducing, not simply clinging on.
Sightings followed a clear seasonal pattern: dolphins were most visible in December and through the winter months, and the team recorded none at all in October 2023 or across July and August of 2024, likely tied to shifting water levels and turbidity. One detail from the study stands out. The Buriganga's native fish community has been so thoroughly wiped out that the dolphins appear to be surviving largely on invasive suckermouth catfish (Hypostomus plecostomus, known locally as sakar fish) — an animal considered a pest in most of the rivers it has colonised.
Zooming out: 2,307 dolphins across the country
The Buriganga findings sit inside a much larger picture. A baseline survey conducted jointly by Bangladesh's Forest Department and the Wildlife Conservation Society (WCS) Bangladesh, funded by the World Bank and carried out between 2024 and 2025, covered close to 4,900 kilometres across 45 rivers nationwide. It counted 2,307 Ganges river dolphins in total and identified 25 priority hotspots requiring urgent conservation attention.
Results were presented at a Forest Department event in Dhaka's Agargaon in October 2025, timed to International Freshwater Dolphin Day. Along one 305-kilometre corridor covering the Turag, Buriganga, Bongshi, Surma and Kalni rivers — all of them heavily polluted — the survey team still found 27 dolphins in total. Dr. Zahangir Alom, WCS Bangladesh's country director, who led the survey, explained that dolphins in these particular rivers are largely surviving on invasive sucker fish rather than their natural prey — a quiet food crisis playing out beneath the water's surface. The same survey found that pollution and the widespread use of gillnets have shrunk usable dolphin habitat nationally by close to 30 percent.
Where does the Shitalakhya fit in?
The Shitalakhya doesn't appear on the list of rivers surveyed for dolphin hotspots in the most recent count — which is worth saying plainly, since headlines about "Dhaka's rivers" tend to blur several waterways together. But the Shitalakhya, Turag, Balu, Dhaleshwari and Buriganga have long been treated as one interconnected system by planners and ecologists alike: five rivers that ring Dhaka, historically shared the same dolphin populations before urban growth fragmented the network, and today share strikingly similar pollution profiles. A tender document from the Bangladesh Water Development Board lists textile and dyeing waste, jute-mill effluent, thermal power discharge, cement-factory runoff, heavy metals and untreated municipal sewage among the pollutants degrading the Shitalakhya — almost the identical list of culprits blamed for the Buriganga's collapse.
There is a policy angle here too. During the tenure of Bangladesh's previous interim government, then environment and water resources adviser Syeda Rizwana Hasan announced that Bangladesh was working with the World Bank to restore navigability on the Dhaleshwari, Turag, Shitalakhya and Balu rivers, with the Buriganga notably left off that particular list "due to some dredging complications." In effect, the Shitalakhya is currently positioned as one of the rivers Bangladesh is actively trying to bring back to health, even though it hasn't yet turned up in a dolphin count the way the Buriganga has. If the species is genuinely as adaptable as the Buriganga data suggests, a cleaner, better-flowing Shitalakhya could plausibly become habitat again — but that remains a hope rather than a documented fact at this point, and it is worth being precise about that distinction.
How polluted are these rivers, really?
The numbers are stark. A pollution-source survey presented to the Ministry of Environment, Forest and Climate Change in August 2026 identified 224 separate points discharging waste into the Buriganga and Turag — 166 of them along the Buriganga alone. Industrial effluent, including dyes, chemicals and heavy metals, accounted for an estimated 55 percent of the pollution load; organic waste, pathogens and ammonia made up roughly another 25 percent. Dissolved oxygen levels in the Buriganga were measured at between 1.70 and 2.68 milligrams per litre, well below the roughly 5 mg/L considered the minimum for a healthy river ecosystem. Presenting the assessment, Bangladesh Navy Rear Admiral Abdullah Al Maksus described the river's condition as extremely critical.
Dhaka's sewage infrastructure is a large part of the problem. Only about 20 percent of the capital is connected to a sewer network, and the city's single treatment plant, at Pagla, processes just 30 to 40 million litres a day against a total flow closer to 1,250 million litres. The remainder goes straight into the river system — Buriganga, Turag, Balu and Shitalakhya alike.
How endangered is the species, exactly?
Globally, the Ganges river dolphin is listed as Endangered on the IUCN Red List, a classification last formally reassessed by the IUCN Cetacean Specialist Group in 2022 — a panel that included some of the most recognised names in freshwater cetacean research: Brian D. Smith of the Wildlife Conservation Society, Dr. Gill T. Braulik of the University of St Andrews, Dr. Md. Zahangir Alom of WCS Bangladesh, and Dr. Shambhu Paudel of the University of Arizona. Bangladesh's own National Red List, assessed in 2015, places the species one notch lower, as Vulnerable — a reminder that global and national assessments don't always move in lockstep, since they weigh different population baselines and geographic scope.
Recent survey work suggests the total South Asian population may be considerably larger than long-standing estimates of roughly 1,200 to 1,800 individuals. A 2025 nationwide survey in India recorded 6,324 dolphins: 3,275 in the Ganges mainstream and 2,414 across its tributaries, plus 584 in the Brahmaputra mainstream and 51 more in its tributaries. Bangladesh's 2,307 add substantially to that regional total.
It's tempting to read these larger numbers as straightforward good news, and in one sense they are. But researchers are generally cautious about crediting genuine population growth versus simply far better survey coverage than earlier decades achieved. The underlying threats — dams, barrages, gillnets, siltation and pollution — have not gone away.
What the law actually says
Bangladesh's principal wildlife statute, the Wildlife (Conservation and Security) Act, 2012, gives the Ganges river dolphin formal legal protection. Its penalty provisions have been reported inconsistently across news coverage over the years — some reports cite terms up to three years' imprisonment or a fine of roughly Tk 3 lakh, others cite up to five years and Tk 5 lakh for repeated offences — which likely reflects amendments to the law and differing charges rather than any single fixed figure. What's consistent is that killing or possessing a dolphin or dolphin-derived product is a punishable offence under the Act.
That law also underpins Bangladesh's network of dedicated dolphin sanctuaries: three in the Sundarbans (Dhangmari, Chandpai and Dudhmukhi, declared in 2012, joined by Shibsha in 2020) and three more at the Padma–Jamuna confluence (Nagarbari-Mohanganj, Nazirganj and Shilanda-Nagdemra, all declared on 1 December 2013).
Beyond the law itself, the Ministry of Environment, Forest and Climate Change — working with the Bangladesh Forest Department and support from UNDP and the Global Environment Facility — adopted a ten-year Conservation Action Plan for the Ganges River Dolphin and Irrawaddy Dolphin of Bangladesh, 2021–2030. It sets out the coordination, monitoring and habitat-expansion work needed to shift the species off its current trajectory, and remains the closest thing Bangladesh has to a national roadmap for freshwater dolphin recovery.
Bangladesh's environment portfolio has changed hands since that plan was adopted. Following the February 2026 general election, Abdul Awal Mintoo took over as Minister of Environment, Forest and Climate Change under Prime Minister Tarique Rahman's government, succeeding Syeda Rizwana Hasan, who had held the post under the preceding interim administration. The August 2026 pollution-source survey and clean-up drive on the Buriganga and Turag suggests the file has stayed active under the new ministry, though it will take a few budget cycles to know how much of the 2021–2030 action plan survives the transition intact.
A global emergency, not just a local one
Bangladesh's dolphins are part of a much larger, and much grimmer, global story. Freshwater dolphin populations worldwide have fallen by an estimated 73 percent since the 1980s, driven by dam construction, unsustainable fishing, pollution and, increasingly, climate-driven drought — the loss of more than 150 river dolphins in the Amazon's Lake Tefé during a severe 2023 drought is often cited as a warning of what may lie ahead elsewhere. In October 2023, Bangladesh joined ten other nations — Bolivia, Brazil, Cambodia, Colombia, Ecuador, India, Nepal, Pakistan, Peru and Venezuela — in signing the Global Declaration for River Dolphins in Bogotá, committing to expand protected river habitat, phase out destructive fishing gear, and improve water quality across the world's six surviving river dolphin species.
Why a blind dolphin in a dirty river matters
It's worth stepping back and asking why any of this deserves attention beyond the novelty of a wildlife-in-the-city story. River dolphins sit near the top of the food chain in freshwater systems, and because they depend on reasonably healthy fish stocks and clean water to survive, their presence, or absence, tends to track the underlying health of the river fairly closely. Speaking at the October 2025 event marking Bangladesh's national survey results, then environment adviser Syeda Rizwana Hasan put it plainly:
The same untreated sewage and industrial effluent that has pushed the Buriganga's dolphins onto a diet of invasive catfish is also the water that millions of people living along these rivers depend on, directly or indirectly, for washing, fishing and irrigation.
What comes next
None of this is a solved problem, and nobody studying these rivers is describing it as one. But there is a reasonably concrete list of steps that would move the needle: enforcing the effluent-treatment-plant requirements industries are already supposed to meet; extending Dhaka's sewerage network beyond its current 20 percent coverage; following through on the Shitalakhya–Turag–Balu–Dhaleshwari restoration financing already discussed with the World Bank; expanding protection at the dolphin hotspots identified in the 2024–2025 national survey; and building out the district-level rescue and monitoring networks proposed alongside it. None of these are exotic solutions. Mostly, they are a matter of political follow-through on plans that already exist on paper.
Conclusion
A dolphin surviving in one of the most polluted rivers on the planet is, depending on how you look at it, either an inspiring story about resilience or a fairly damning indictment of what has been allowed to happen to that river in the first place. It is probably both. The Buriganga's dolphins haven't thrived so much as endured — breeding, but on an unnatural diet, in water that would be lethal to most other native species. Whether the Shitalakhya, the Turag, and the rest of Dhaka's river system ever host dolphins again in meaningful numbers will depend less on the animals themselves, which have already shown they can adapt to conditions few would have predicted, and more on whether Bangladesh follows through on the restoration and enforcement plans that are, for now, still mostly promises.
Frequently asked questions
Is the Ganges river dolphin the same as a shark or a sea dolphin?
No. The Ganges river dolphin (Platanista gangetica) is an obligate freshwater cetacean, unrelated to sharks and physiologically distinct from marine dolphins. It cannot survive in salt water and lives only in the rivers of the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu systems.
Why are Ganges river dolphins blind?
Their eyes lack a lens and can only detect light and dark, an adaptation to the silt-heavy, low-visibility rivers they inhabit. They compensate with echolocation, using ultrasonic clicks to locate prey and navigate.
Can Ganges river dolphins really survive in heavily polluted water?
The Buriganga findings show they can persist, and even breed, in severely degraded conditions, though evidently under stress: surviving on invasive fish rather than native prey, and only in specific, less-disturbed pockets of the river. This is closer to resilience under duress than a sign the pollution is not a serious problem.
What is Bangladesh doing to protect river dolphins?
Legal protection comes from the Wildlife (Conservation and Security) Act, 2012, backed by six designated dolphin sanctuaries and the ten-year Conservation Action Plan for the Ganges River Dolphin and Irrawaddy Dolphin of Bangladesh (2021–2030). Bangladesh is also a signatory to the 2023 Global Declaration for River Dolphins.
- Mongabay (Sept 2026) — Against the odds, endangered dolphins survive in Bangladesh's polluted river
- Journal of Asia-Pacific Biodiversity — Buriganga River dolphin survey, 2023–2024
- Dhaka Tribune (Aug 2026) — Survey finds 224 pollution outlets in Buriganga, Turag
- The Daily Star (27 Oct 2025) — 2,307 dolphins found in the country's rivers
- The Business Standard — Securing a safe future for the river dolphins of Bangladesh
- IUCN Red List of Threatened Species — Platanista gangetica (2022 assessment)
- National Red List of Bangladesh, Volume 2: Mammals — Platanista gangetica (2015)
- Conservation Action Plan for Ganges River Dolphin and Irrawaddy Dolphin of Bangladesh, 2021–2030 (MoEFCC / Bangladesh Forest Department / UNDP-GEF)
- Wildlife (Conservation and Security) Act, 2012, Government of Bangladesh
- Global Declaration for River Dolphins, Bogotá (October 2023) — WWF / signatory reporting
- Wikipedia — Shitalakshya River; Nagarbari-Mohanganj, Nazirganj, Shilanda-Nagdemra & Shibsha Dolphin Sanctuaries
Figures current as of September 2026. River-survey and policy data are updated periodically — worth a quick check against the sources above before republishing at a later date.
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