Aquatic Life of Nepal's Rivers: Dolphin, Gharial & Golden Mahseer

Nepal is best known for tigers, rhinos and mountains, but its warm lowland (Terai) rivers hold some of South Asia's rarest freshwater animals. Three species stand out as flagships for river conservation: the Ganges river dolphin (Nepali: susu), the gharial crocodile, and the golden mahseer or sahar. Each is a barometer of river health, and all three are threatened by the same broad pressures - dams and barrages, water abstraction, gill-net fishing and pollution.

These species share the perennial rivers that drain into the Ganges basin. The Karnali system in the west (including the Mohana and other tributaries around Bardia National Park), the Narayani-Rapti-Babai rivers around Chitwan and Bardia in the centre-west, and the Koshi (Sapta Koshi) in the east are the strongholds. Because these rivers cross into India, effective conservation depends on transboundary cooperation as well as domestic action.

All three animals are protected in Nepal. The Ganges river dolphin and the gharial are listed among the protected fauna of the National Parks and Wildlife Conservation Act, 2029 BS (1973 AD), which prohibits killing, capture or trade. The golden mahseer is not a listed protected species but is managed through fishing regulations, catch-and-release angling norms and community stewardship because of its Endangered global status.

The Ganges river dolphin (Platanista gangetica), known locally as susu after the sound of its breathing, is a nearly blind freshwater dolphin that navigates muddy rivers by echolocation. It is classed as Endangered on the IUCN Red List and is the only cetacean and the only aquatic mammal protected under Nepal's National Parks and Wildlife Conservation Act. Globally the species survives only in the Ganges-Brahmaputra-Meghna river system across India, Nepal and Bangladesh, with a total population commonly estimated at a few thousand animals.

In Nepal the dolphin clings on in two main river systems. A 2016 government survey estimated about 52 dolphins in the country - roughly 43 in the Karnali River and its tributaries (which feed the Mohana around Bardia) and about 9 in the Koshi in the east. Numbers this low make the Nepali population extremely fragile, and researchers have repeatedly called for a longer, updated national census because the 2016 count was brief.

There have been encouraging signs. After roughly a decade with no confirmed sightings, dolphins were photographed again in the Narayani River in 2022, and seasonal movement into tributaries such as the Mohana during the monsoon shows the animals still use Nepal's western rivers. Even so, the population is considered stagnant at best, and small, isolated groups remain highly vulnerable to a single bad flood, drought or barrage-related change in flow.

The gharial (Gavialis gangeticus) is a fish-eating crocodilian instantly recognisable by its long, thin snout; mature males grow a bulbous nasal boss called a ghara, which gives the animal its name. It is Critically Endangered on the IUCN Red List (listed as such since 2007) and is harmless to people, catching fish rather than large prey. In Nepal it survives mainly in four rivers: the Rapti, Narayani, Babai and Karnali.

To reverse a collapse that had left only around 80 gharials in Nepal, the government established the Gharial Breeding Center at Kasara in Chitwan National Park in 1978, now run with the National Trust for Nature Conservation (NTNC). The centre collects eggs from natural nesting sites, hatches them safely and rears juveniles for several years before release. Between 1981 and 2017 about 1,246 captive-reared gharials were released into the Rapti, Narayani, Kali Gandaki, Koshi, Karnali and Babai rivers, and translocations continue - for example, 25 gharials were moved to Shuklaphanta National Park in 2024.

Annual monitoring shows a slow recovery in Chitwan's core rivers. The December 2025 census (conducted 7-15 December 2025) counted 366 gharials across the Narayani and Rapti, up from 352 the previous year. The Rapti has become the main stronghold with 231 animals (up from 206), while the Narayani slipped to 135 (down from 146). Surveyors documented only nine adult males, underlining how few breeding-age individuals remain despite the rising totals.

The golden mahseer (Tor putitora), called sahar in Nepali, is a large golden-scaled cyprinid nicknamed the 'tiger of the river' for its power on the line. It is Endangered on the IUCN Red List, with a population estimated to have fallen by more than half over about three generations (roughly 21 years) due to overfishing and habitat change. The species is transboundary, occurring in Bangladesh, Bhutan, India, Nepal and Pakistan.

In Nepal the mahseer inhabits fast, clean stretches of the Karnali, Seti, Babai, Sharada, Trishuli, Kali Gandaki and Mahakali, migrating upstream to spawn. It is the centrepiece of Nepal's fly- and lure-fishing tourism, especially around Bardia National Park, where the Babai was reopened to permit-based angling in 2011. Strict catch-and-release is the accepted standard for mahseer angling in Nepal, so the fishery is built around the challenge and the photograph rather than the plate.

Community-led conservation is expanding. Between 2024 and April 2025 the NTNC, with support from IUCN Save Our Species and the Fondation Segre Conservation Action Fund, ran a project on the Babai and Sharada rivers that surveyed fish diversity (recording 17 fish species), trained thousands of residents, and set up youth 'river guard' patrols to curb destructive fishing and protect mahseer spawning and hatchling sites.

This is a common exam and quiz question, and the accurate answer needs care. It is India - not Nepal - that has an officially declared national aquatic animal: India designated the Ganges river dolphin as its National Aquatic Animal in 2009 (formally notified in 2010). Nepal has not enacted an equivalent official 'national aquatic animal' designation.

Within Nepal, however, the Ganges river dolphin is widely treated as the country's flagship river mammal. It is the only aquatic mammal on Nepal's list of protected wildlife under the NPWC Act, and it features prominently in national river-conservation planning. So if a question asks for Nepal's national aquatic animal, the honest response is that the dolphin is Nepal's most iconic and legally protected river mammal, while the formal 'national aquatic animal' title belongs to India.

For anglers and biodiversity enthusiasts, the golden mahseer plays a comparable flagship role for Nepal's fish, and the gharial for its reptiles - together the three make up the country's best-known 'big three' of river wildlife.

Although a dolphin, a crocodilian and a fish look very different, they face overlapping dangers. The biggest is the fragmentation of rivers by dams, barrages and irrigation weirs, which block fish migration, alter the seasonal flows that dolphins and gharials depend on, and cut populations off from one another on both sides of the Nepal-India border.

Fishing pressure is the second major threat. Gill-nets drown dolphins and gharials as bycatch and strip rivers of the fish all three species need, while illegal dynamite and poison fishing devastate mahseer stocks and their prey base. Sand and gravel mining destroys the shallow bars and banks that gharials use for basking and nesting, and pollution from towns, farms and industry degrades water quality across the lowland rivers.

Climate change adds a further layer of risk through more erratic monsoons, damaging floods and lower dry-season flows that shrink and warm the pools these animals rely on. Because the same rivers sustain all three species, protecting one usually helps the others - which is why conservation in Nepal increasingly focuses on whole river stretches rather than single species.

The Department of National Parks and Wildlife Conservation (DNPWC) leads legal protection and monitoring, including the annual gharial census and Nepal's river-dolphin conservation planning. The NTNC operates the Kasara Gharial Breeding Center and community programmes, while WWF Nepal has led river-dolphin surveys and habitat work on the Karnali and Narayani. IUCN provides the Red List assessments that guide priorities and, with partners such as the Fondation Segre, has funded mahseer conservation.

For visitors, the two best regions to encounter this wildlife are Bardia National Park in the west - on the Karnali, Babai and Mohana, the core habitat for dolphins, gharials and mahseer - and Chitwan National Park in the centre, where boat trips on the Narayani and Rapti offer the most reliable gharial sightings and, with luck, dolphins. Responsible angling operators run permit-based, catch-and-release mahseer trips out of Bardia and the Seti-Karnali confluence.

The practical ways to help are consistent across species: buy park permits and use licensed guides, insist on catch-and-release for mahseer, never buy wildlife products, report gill-net or poison fishing, and support the community river-guard groups that now patrol key stretches. Small, isolated populations mean that avoiding a single avoidable death - a netted dolphin or a poisoned pool of mahseer - genuinely matters.