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Episode 318: Almost Gone, The Gharials

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The uniquely wonderful Gharial (image from nationalzoo.si.edu)

The unique gharial was once a common sight in rivers throughout India, Nepal, Pakistan, Bangladesh, Bhutan and Myanmar, but today it is extinct in all but 2% of its former range, in Nepal and India. The second largest crocodilian behind the saltwater croc (although significantly less aggressive), the gharial is easily identified by its unusual elongated narrow snout, with a bulbous protrusion at the end that resembles a traditional Indian earthernware pot, called the ‘ghara’. This is much more distinctive in males, and is used to make the hissing noises gharials use to communicate. They are also the only crocodilian species to display sexual dimorphism.

The gharial diverged away from the rest of the crocodiles around 38 million years ago, and is a sister group to the other species. Although they exclusively dwell in freshwater, fossil evidence suggests that their ancestors were once saltwater species, and only relatively recently moved into freshwater. Gharials were the sole member of their family Gavialidae, but recent genetic evidence has placed the false gharial, or Sunda or Malayan gharial, in the same family.

Unique crocodile with unique ecology

Gharials are very unique looking crocodilians, and they also have some unusual ecology that separates them from the rest of their scaly brethren. In a study comparing the ecology, life history and evolution of all 23 crocodilian species, researchers determined that the gharial has very unique functional roles compared to the rest of the group, meaning that their disappearance from the wild would be a huge loss.

Gharials cluster in huge numbers for mating and nesting in the dry season in mid February, the egg laying on exposed riverbanks in mid March to early April. Unlike other crocodiles, gharials don’t ferry the young to and from the water, but one large dominant males and several females will guard the creche as they learn to use the river. As the monsoon waters rise, the gharials, both young and old, will disperse across the river system, making migrations as far as 200 kilometres.

A Gharial in charge of a creche of hatchlings (image from India Today)

They are the most thoroughly aquatic crocodilian, spending almost all their time in the water, emerging only to bask. This watery lifestyle is reflected in their diet, which is made up almost entirely of fish. Their narrow snout provides them with less resistance on their aquatic hunts, and their intersecting, needle like teeth enable them to trap fish, after which they swallow them whole. This predation on fish is vitally important, as gharial prey on some of the biggest fish, keeping their numbers low, and allowing smaller fish to thrive in their absence, which provides the perfect balance for fishermen fishing the rivers the gharials call home.

A Gharial on the rare occasion it leaves the water, basking on a mudbank (image from www.conservationleadershipprogramme.org)

This unique ecology makes gharials interesting, but it also puts them at risk. Traits like clustering together to breed, being unable to dig burrows and travel over land thanks to their stubby legs, puts gharials at a higher risk of extinction than their other crocodilian counterparts.

Conservation success to conservation failure: the history of the Gharial

Now listed as critically endangered by the IUCN, Gharials once thrived throughout all major river systems in the northern Indian subcontinent, but by the 1980s, the species was almost extinct.

The gharials are facing threats from every angle, but perhaps one of the most significant are the changes that are inflicted upon their river habitats through dams, irrigation canals, and riparian agriculture on the banks of rivers. Just like other threatened species such as the Ganges River Dolphin, Smooth Coated Otter and the Mugger Crocodile, gharial populations are battered by human developments along river systems. They are often trapped upstream by dams, away from vital breeding and hunting grounds. If the gharials themselves are not trapped, fish shoals can be caught behind the structures, limiting the available prey. Agriculture along the banks of river is very popular, as the rich mud makes the ground very fertile, but this affects the gharials breeding and basking grounds. Unlike other crocodilians that can raise up on their legs and walk across the land, the structure of the gharials limbs mean that they can’t walk very far at all, but rather slither short distances on their bellies. This means they cannot disperse into other river systems to avoid disastrous habitat changes.

They are also hunted for their skin and other body parts for traditional medicine, and their eggs are also taken for food. Fishermen also see the gharials as competition, and often they are killed outright, or are caught in gill nets and drown. In some areas, fishing is banned, but without offering fisherman any competition or alternative for their lost livelihood, tempers rise, and often this frustration is taken out on the gharials.

An unfortunate gharial caught in a fishing net (image from www.indianarrative.com)

In light of the enormous declines from the 1940s onwards, in 1972 the Indian Government placed the gharial under the banner of the Wildlife Protection Act, and a few years later, set up the ambitious Project Crocodile. Between 1975 and 1982, this ambitious conservation endeavour set up sixteen crocodile rehabilitation centres and five sanctuaries. Today, most of the existing gharials live in these sanctuaries, with the largest population inside National Chambal Sanctuary in India. As part of Project Crocodile, nests were located in the wild and the eggs removed and taken to the rehab centres for captive breeding. Once the gharials had hatched and matured, they were released into the wild in huge numbers from the 1980s onwards. This project was seen as wildly successful, and virtually all money was withdrawn from the project overnight, and the egg collection programme stopped. Pretty quickly, gharial numbers began to plummet again. This is largely because inexperienced gharials were released into unsuitable, disturbed habitat and either starved due to lack of food, drowned in nets or were trapped in areas of the river as more and more development occurred. Furthermore, the project made the fatal mistake of not involving local people in conservation efforts. Project Crocodile, once seen as such a monumental success, was beginning to look like a colossal failure as gharial numbers fell yet again.

A Gharial cruising through the rivers of the National Chambal Sanctuary (image from roundglasssustain.com)

Conservation optimism

Although the well-meaning Project Crocodile hasn’t exactly saved the species from certain extinction, conservationists are realising the errors of the past and beginning to correct them. There is now understanding that gharials don’t just need to bred in captivity, but also need prime, protected habitat for these individuals to be released into. Even something as simple as releasing the gharials at the correct time of year has proved to be vital. By opting to release captive individuals at peak fish abundance, this prevents the issues seen with starving gharials dying off, as they fail to catch fish with their inexperience, after spending their early life being fed by keepers. Hungry gharials also fail to migrate and breed, so providing them with the best possible start, the production of future generations can also be secured.

A captive bred gharial being released into a National Park (image from the IUCN)

In Nepal, parks like Banke National Park, where there is a significant gharial population are pushing for more conservation interventions in the Rapti River, which is currently free of gharials but would be a good place to introduce them, given the low pollution levels and high numbers of fish prey. However, reintroductions here would put fisherman’s’ livelihoods at risk. Learning from the failures of the past efforts to involve locals, conservationists are suggesting issuing licenses to limit fishing to certain parts of the river and banning some of the most dangerous nets, but also providing locals with the expertise to set up fish ponds so they can avoid overfishing the main rivers. In the Girwa River in India, habitat modification has also been tried with some impressive success. Artificial sandbanks have been built in the middle of the river, allowing gharials a place to bank and nest, free of human interference. Since this intervention, there has been a significant improvement in hatchling success. In some areas, unmanned aerial vehicles (UAVs) are now being used to monitor and survey gharial populations. These drones take thousands of images in a single flight, and software can now differentiate between different species, even the similar looking gharial and mugger crocodile. This is far less invasive than research boats chugging up and down the rivers, disturbing gharials, particularly important during the nesting season.

A hatchling gharial handled by a conservationist from the Zoological Society of London’s EDGE programme (image from ZSL)

Thanks to their incredible uniqueness, the gharial is part of the Zoological Society of London’s EDGE (evolutionarily distinct and globally endangered) of extinction programme, which directs funds, research and conservation efforts towards the worlds most unusual and threatened species. Currently three fellows are working on Gharial projects, focusing on better understanding ecology and habitat use to ensure conservation interventions have the best outcome. ZSL also worked with locals to set up ‘Gharial Guard Groups’; teams that patrol gharial hotspots and monitor and prevent illegal mining, river bed dredging and over fishing. These ambassadors also teach their communities about the importance of co-existing with gharials, and how these huge crocodiles are so vital to the healthy functioning of their river ecosystems. WWF India is also heavily involved in the species recovery programme.

The International Reptile Conservation Foundation is an international organisation of people from a range of disciplines that carry out surveys, captive breeding and wild restocking, as well research, awareness programmes and government lobbying, they have recognised just how important it is for there to be sufficient, healthy, protected river habitats for gharials to be released into; without this, the species can never thrive outside of breeding centres. You can check out their work at Gharial | reptile conservation (ircf.org).

The Gharial Ecology Project conducts research on the ecology of the Gharial in Chambal National Sanctuary to better understand how to conserve this incredible crocodilian. You can check out their research, outreach and conservation work on facebook at Gharial Ecology Project | Etawah | Facebook

Awesome videos!


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Lee, M.S.Y. and Yates, A.M. (2018) ‘Tip dating and homoplasy: reconciling the divergences of modern gharials with their long fossil record.’ PNAS

Martin, B.G.H. and Bellairs, A.D.A. (1977) ‘The narial excrescence and pterygoid bulla of the gharial.’ Journal of Zoology

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February 08, 2023
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