Saving the world’s rarest crocodile from extinction

Published On: May 21, 2021 09:35 AM NPT By: Karun Dewan

Karun Dewan

Karun Dewan

Dewan is a Program Associate - Freshwater, at WWF Nepal.

Conserving gharial is just one example of how hard it is to protect one species from extinction. There is no undo button once these species are lost.

When we talk about Nepal’s iconic wildlife species, it is the tiger, rhino or elephant that often pops into one’s mind. Even the blackbucks and the wild buffaloes get significant attention in terms of conservation initiatives. However, on the occasion of Endangered Species Day, let’s focus on a species which is twenty times more endangered than the iconic tiger – the gharial. The reptile with its foot-long slender snout has more than a hundred razor sharp teeth, and is critically endangered and conserved under the Schedule I - Protected Reptile of the National Park and Wildlife Conservation Act 1973.

The gharials are considered living fossils, having evolved around the era of dinosaurs, some 65 million years ago. By the mid 70s they were limited to just 2% of their historical range, pushed to the verge of extinction with a 98% decline between 1940 and 2006. Mostly found in major river systems of Myanmar, Pakistan, Bhutan and Bangladesh, the previously flourishing crocodile can now be found only across fragmented freshwater stretches of Nepal and India-- with around 550 breeding populations remaining in the wild. 

The gharial’s preference for fine sand banks across river stretches with zero or very low levels of disturbance, deep pools with river confluence and prey availability has resulted in their categorization as an indicator species for freshwater ecosystems. Presently, there are 84 gharials in the Narayani River, 82 in Rapti, 31 in Babai and 1 in Karnali, totaling 198 gharials in Nepal. However,  fewer than 100 mature adults remain. Despite the importance of freshwater species, conservation interventions rarely target freshwater species or habitats, partly as protection of freshwater environments require large-scale, multi-sectoral efforts. Nevertheless, the government has been conserving the species in alignment with the Gharial Conservation Action Plan (2018-2022) which encourages both in-situ and ex-situ conservation efforts to recover the population in the wild. 

Gharial conservation in Nepal dates backs to 1975, when Scottish researcher H.R. Austurn studied the species in Chitwan National Park (CNP), and took some eggs to Odisha, India for artificial incubation. This then inspired Rampreet Yadav to incubate the eggs in dug-out sand pits in CNP as well. Three years later, the Gharial Conservation Breeding Center (GCBC) was born as an ex-situ facility for breeding and rearing gharials. The GCBC collects gharial eggs from Rapti and Narayani Rivers, incubating them in facilities and rearing hatchlings until they attain maturity for eventual release into the wild and maintain their viable sub-population. The WWF Nepal, along with conservation partners, supported upgradation of the center through construction of larger breeding pools, upgraded visitor center, health laboratory and fish farms between 2010 and 2013. 

Since 1981, Nepal has succeeded in introducing over 1,580 crocodiles raised at the breeding center into their natural habitat as well as gifted 32 gharials, 631 gharial eggs and 20 mugger crocodile eggs to zoos and captive facilities in the USA, France, India, Japan and Bhutan. Despite these numbers, the present population of gharials in the wild are relatively low. Hatchlings are hypothesized to be swept away during the monsoon floods, resulting in a low natural recruitment rate. Around 75% of the released crocodiles cross the Gandak barrage and enter Indian territory. In one such incident, a subadult gharial travelled as far as 1062 km from its release site in Chitwan to Raninagar in West Bengal, India. 

Hatchling survival rates were shown to be comparatively lower in years of extensive flooding, such as 2017 and 2019. And hatchling mortality is also affected by predation from birds such as the grey-headed fish eagle as well as mugger crocodiles. With gharial population along Narayani and Rapti rivers showing signs of gradual recovery, the GCBC since 2017 has been collecting only those nests deemed vulnerable to negative impacts of flooding, human disturbance, wildlife movement, etc, recruiting fishermen from the indigenous Bote and Musahar tribes to watch over these nests.

Ranging from degradation and destruction of their natural habitats; such as flow modification, pollution, invasive species, sand mining in rivers, to prey depletion, the threats to the species are varied. Local communities, along with park authorities and conservation partners, have been working to conserve this keystone freshwater species through continued joint monitoring, river patrolling, and habitat management initiatives. 

Habitat degradation is caused by a series of anthropogenic activities, for instance the untreated waste generated in nearby towns and urban areas find their way to rivers, degrading gharial habitats, whereas some gharials are found injured due to entanglements in fishing nets. Increased development demands for sand and gravel, often extracted from river banks, cause additional habitat disturbances. 

Development of large irrigation and hydropower projects have resulted in decreased water flow in rivers, negatively impacting  the habitat of the reptile. For instance, the barrage along the Nepal-India border nullifies the movement of gharials returning upstream. Transboundary cooperation through sharing of expertise and implementation of complementary conservation and monitoring programs are critical in addressing these challenges, alongside integrating wildlife friendly structures.

Conserving gharial is just one example of how hard it is to protect one species from extinction. There is no undo button once these species are lost. According to a Living Planet Report, there has been a 84% decline in freshwater species since 1970, among which the most vulnerable are freshwater reptiles, amphibians, and fishes; putting almost one in three freshwater species on the verge of extinction.

Keeping this in mind, an international group of freshwater ecosystem experts gathered in 2019 to define priorities for bending the curve of freshwater biodiversity loss, and set out an ambitious Emergency Recovery Plan for Global Freshwater Biodiversity. The plan includes six sets of pragmatic priorities – allowing rivers to flow more naturally, reducing pollution, protecting critical wetland habitats, ending overfishing and unsustainable fish mining, controlling invasive species, and safeguarding and restoring connectivity. The global demand for freshwater increases by 1% every year, however efforts to conserve freshwater ecosystems and species are often lacking.   

Measures such as no-go zones for fishing and mining in critical sites, increased public awareness and continued community involvement will be critical in safeguarding the gharial as well as other freshwater species in the long-term.  Conservation plans must recognize that freshwater conservation has to occur over larger spatial scales rather than terrestrially for conservation to be effective. 

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