World Croc Day 2020: Gharial conservation in Nepal
World Croc Day 2020
- Chandra Mani Aryal
Crocodiles are the tropical semi aquatic reptiles that are found in Asia, the Americas, Africa and Australia. There are twenty four species of Crocodiles in the world of which Nepal is home to two species namely mugger crocodiles (Crocodylus palustris) and Gharial (Gavialis gangeticus).
Among these two, gharial is more threatened to extinction. Conservation actions are in place but they are insufficient to overcome the threats. There is a need to amend the conservation intervention made.
Gharials are the freshwater crocodiles and one of the longest crocodiles in the world. They are known for their long and thin snout and a growth in the snout of male gharial which is known as ‘ghara’. They have specialized diets i.e. they feed only on fish. Until 1943, they were recorded from the major river systems of Pakistan, Myanmar, Bhutan, Nepal, Bangladesh and India. But now, they are confined to few rivers of Nepal and India. In Nepal, the individuals of Gharials can be found in Narayani, Rapti and Babai rivers with no record of species from Koshi and Mahakali rivers. The population of the gharials in the world have declined by nearly 98% compared to the historic number while their habitat has been reduced by 94%.
Anthropogenic activities are the major threats to the species. The decline of the Gharials of Nepal are mainly attributed to the spray of DDT (Dichorodiphenyltetraacetate) during the Malaria eradication program operated in the 1960s. The population of gharials were largely increased at that time while the mobility of humans also increased by many folds. Additionally, constriction of dams in the rivers, unsustainable sand mining activities, pollution in the water, poaching of gharials for pelts and collection of the eggs for consumption grew significantly which ultimately increased the threats to Gharials in Nepal. Besides gharials are occasionally caught and on the fishing net as bycatch. Furthermore, due to the impact of predators and periodic floods in the river system greatly reduces the survival rate of Gharials to about 1%.
To reduce these threats, Gharial breeding centers have been used as one of the tools. Few months back, when wild hatchling was reported at Babai river, that made huge news in national and international media. But we all failed to acknowledge that gharials are laying eggs in the river system of Nepal but they were not hatching in natural habitat primarily because almost all the eggs that were seen in the nest built by gharials are collected and taken to breeding centers for hatching.
On the initiation of Late Tritha Man Maskey, Nepal began conservation of Gharial back in 1976 by establishing Gharial Breeding Center at Kasara of Chitwan National Park. Another breeding center was established later on at Thakurdwara of Bardiya National Park. Both of these breeding centers are not pure breeding centers as their name suggests, as no fertilization takes place at the breeding center. In fact, in both these centers, eggs and young hatchlings are collected from the natural habitats and they are raised for some duration. After growing for a certain period of time, they are released back to the natural habitats when they reach the size of at least 1.5 m long.
This intervention can be considered partially successful as the population status of the Gharial in the natural river system has remained almost constant of late. But, starting from 1981 till date more than 1100 individuals of gharials are released to different river systems of Nepal. But the population of the Gharial are nearly 10% of the total released individuals indicating the need to question some of the approaches used for conservation. In the last week of May 2020, a gharial made news when it travelled nearly 1100 km in 60 days and was trapped in a fishing net at Hooghly near Rani Nagar Ghat in West Bengal. Many of these released gharials are either taken away by floods or they travel themselves and never return back.
First and foremost, the question is about the breeding centers itself. For the survival of the population, a balanced male female ratio is vital. In case of Gharials, the sex of the individuals is defined by the temperature at which they are hatched. Prakash Chandra Aryal, founder and herpetological researcher associated with Companions for Amphibians and Reptiles of Nepal (CARON) doubts the facilities within the breeding centers are able to maintain optimum temperature to maintain the desirable male female ratio. According to Mr. Aryal, in a natural environment, gharials select the site for nesting based on the texture of the sand. The texture plays an important role in maintaining the hatching temperature.
Though we need detailed research to support this claim, the female biased population of Gharial in Rapti indicates the same problem. To address the lack of male gharial, an individual of male gharial was captured from Babai river and released to Khoriya area of Rapti river in December 2017.
To address the issues related to female biased population, though the natural survival rate of the gharial is very poor, we can intermix our approach. We can collect half evacuated half of the nest to hatch them at the breeding center while the remaining half can be protected and let them get hatched in the natural habitat. In addition to this, other conservation interventions are equally necessary to protect these threatened reptiles. The river training works, sand mining activities and dam construction are significantly affecting the flood dynamics of the rivers and ultimately the breeding and survival ecology of gharials. We have to rethink these activities as well. Additionally, we have to regulate the river polluting activities, fishing and use of pesticides in agriculture.
Gharial conservation activities are prioritized by the government but the interventions made are insufficient to ensure the long-term survival of gharials in Nepal. Regulation of the anthropogenic activities are always vital but equally important are evidence-based interventions. Government should think about taking inputs from the people other than the ones who are working on their behalf. Let’s hope that world crocodile day, which is celebrated each year on 17th of June as a global awareness campaign to highlight the quandary of endangered crocodiles and alligators of the world inspires concerned stakeholders to rethink their approach in gharial conservation.
Mr. Aryal is a researcher of Environment Protection and Study Center.