Do you know there is existence of a beautiful creature in Indian sub-continent which is known as keystone species of healthy freshwater ecosystem? Yes, it is fish eating crocodile and among the longest of all living crocodilians. Gharial (Gavialis gangeticus) is a critically endangered species listed by IUCN and falls under CITIS appendix I. They are easily identified among other crocodiles with long, thin and narrow snout which is regarded as an adaptation to predominantly fish diet. Adult males grow around their nostrils a bulbous nasal appendage called “ghara”, which enhances vocal communication. The name ghara is derived from Nepali/Hindi word which means earthen jar pot. Adult male is about 7-meter-long whereas female is only up to 5 meters. They typically live 40-60 years with an average weight of 350-400 lbs and sexual maturity is attained after 10years. They perform sliding type of movement and their hydrodynamics body allows to be an excellent swimmer. Their interlocking set of teeth (25-29 in each side of upper jaw and 25-26 teeth in lower jaw) is adopted for catching their prey (Shah and Tiwari 2004). Juvenile one cannot catch fish so depends on insects and other small vertebrates. As they are poikilotherms, we can see them on the beaches of freshwater river enjoying sunbath during winter and hiding on shade and under water to cope with hot summer days. Interesting, Gharials have temperature dependent sex determination.

Looking back at the history, Gharials were well distributed on the rivers of great Indian continents from Indus river in Pakistan to Gangetic branches in India not excluding Nepal, Bhutan, Bangladesh and Myanmar. According to the record (Thapaliya et al 2009), there were about 5000 to 10000 gharials in above mentioned region. But sadly, by the time they reached the third generation after 1940, their numbers had dropped by 96% (Maskey, 1989). After the years of 1970s, their numbers were limited to a handful and now found only in Nepal and India with few numbers (Choudhury et al, 2007). Other countries where they have majority, are now limited to history, almost impossible to find at present.

In Nepal, Gharials were found in major rivers Karnali, Koshi and Narayani and Mahakali. At present, the population of Gharial in Nepal is around 198 with six adult males and 79 females (Acharya et al, 2017). Their main numbers are scattered in the Narayani and Rapti rivers around Chitwan National Park, and to some extent in the Babai and Karnali rivers.

The habitat and ecology of Gharial may fascinate us. As they prefer to live in dep and fast following rivers, they mostly spend time in water. They specialize in making nest and egg laying in the sand accumulated on the banks of the river. They love to be exposed on sunlight and warmth for pleasure and relaxation. In summer, they prefer shaded area for water fun during hotter days. Because of their weak limbs, they are not able to walk in semi upright position unlike other crocodiles. It sounds amazing that an adult female can travel up to 80-10 km distance to locate the suitable area for nesting and basking. Mating is seen at the end of the cold season. In wild, she starts to lay egg from last week of march to April first week and she have special technique of burying of egg in sand nest so that egg during incubation gets proper warmth and also protects from water waves.at a time 20-95 eggs are guard to the nest and most eggs are hatched during 67 to 75 days of incubation but depends on temperature. It will take some more hours or days if the nest is built on shaded areas. Adult female also helps to make easy hatching and male is also responsible for parental care during monsoon.

As I have already mentioned that it depends on incubation temperature whether the male is born or the female. This is called temperature dependent sex determination (TSD). There is maximum chance of hatching of female when incubation temperature is maintained between 29 degree Celsius to 31.5 degree Celsius. The possibility of a male being hatched is 89% on 32 degree Celsius and 20% and 15% on 33 and 3.5 degree Celsius (Lang and Andrews 1994). So even a small amount of environmental influence in the ecology of gharial plays a big game.

There are many challenges in conservation of this species in local level. Though there is dedication of government to local bodies to protect and increase the numbers of Gharials, still to achieve a target level is not been successful. There are many causes behind it but the major manmade problems are habitat destruction and unsustainable harvesting. The rivers which are suitable home for Gharials are already polluted due to direct dumping of industrial sewage without treatment/purification. Capture of riverine area for agriculture, use of pesticides and chemical fertilizers which finally drains to the habitat of water animals. Dams are constructed for hydropower, irrigation and to control flood hampers them to bask and care of eggs and young ones. Also, mining, excavation of sand and stone without calculating alternative costs, depletion of fish resources, detrimental fishing are the major factors for the loss of Gharial population day by day. Some people think Gharial body part can be used as ethnic/ endogenous medicine and hunt for it. Human- wildlife conflict also play a major factor to reduce the population of the highly threatened species. Young Gharials may entangle with fishing nets and killed by hunger and fisherman.

Gharials are known to be a climate sensitive crocodilian. Most of the world is suffering from negative impacts of Climate change and global warming, so the Gharials. Temperature dependent Sex determination is affected by the High temperature and low waterfall. This will also alter the water quality and degrade the home of Gharial with its prey.

As Gharials are limited to a small number in some rivers of Nepal and India, so the responsibility of conservation too. Government of Nepal has published Gharial Conservation Action Plan for Nepal (2018-2022) to give a holistic effort towards conservation of this endangered species in in-situ and ex-situ environments. This standard monitoring protocol prepared by Department of National Parks and Wildlife Conservation (DNPWC) helps to maintain in situ and ex situ conservation and also secure future breeding strategies. The main objectives of Gharial Conservation Action Plan (2018-2022) as listed in the plan book are to improve in situ conservation minimizing human interference, enhance research on Gharial, its habitat and prey, maintain ex situ conservation, and implement the reintroducing programs. Other organizations such as NTNC, WWF, IUCN, universities with collaboration are directly involve to uplift the Gharial management in Nepal. Chitwan National Park and Bardia National park are the major home for Gharials. Since 1987, Nepal is a member to RAMSAR convection. Forest policy (2015), wetland policy (2012), National Park and Wildlife Conservation act (1973), Aquatic Animal Protection Act (1961) are some examples of the laws to made for conservation of endangered species of Nepal. Gharial Conservation and Breeding Center (GCBC) has been established to protect the species from extinction. Since 1978, Government of Nepal with support of Germany is continuously working to support breeding and reintroducing program. This was established when the population of Gharial was less than 81 with 1% hatchling survival rate. Now according to the survey conducted in latest, there are 645 in total. Gharial monitoring center (GMC) is also established to collect eggs and set in wild. Crocodile breeding center (CBC) in Bardia National Park is also protecting and maintain the breeding Gharials. Apart from these, DNPWC also works for awareness and research with involvement of user groups of National park buffer zone. Buffer zone management committee is of local groups around the buffer zone of CNP which have formed subcommittee for specially Gharial conservation. This works in local level and found meaningful to protect these species.

Nature has spread beauty in every corner of the world. Come here and watch the Gharials, your visit can be beneficial to protect them. Capture them in the heart, capture them on camera but lets not capture their home.Love every aspects of the nature, they love us more than we imagine.

Green Cheers

References:

Gharial Conservation Action Plan for Nepal (2018-2022)

WWF Nepal (2011), Population Status and Distribution of Gharial in Nepal. WWF Nepal, Kathmandu, Nepal.www.wwfnepal.org

Shah, K. B., and S. Tiwari. 2004. Herpetofauna of Nepal. A Conservation Companion.  Kathmandu, Nepal: IUCN Nepal—The World Conservation Union.

Thapaliya, Bishnu & Khadka, Madhav & Kafley, Hemanta. (2010). Population Status and Distribution of Gharial ( Gavialis gangeticus ) in Nepal. The Initiation. 3. 10.3126/init.v3i0.2422.

Maskey T.M. (1989), Movement and Survival of Captive Reared Gharial in the Narayani River, Nepal.

Lang, Jeffrey. (2019). Gavialis gangeticus, Gharial THE IUCN RED LIST OF THREATENED SPECIES™.

Lang J.W. and Andrews H.V. 1994, Temperature-Dependent Sex Determination in Crocodilians. The Journal Of Experimental Zoology 270:28-44

Krishna Prasad Acharya, Bed Kumar Khadka, Shant R. Jnawali, Sabita Malla, Santosh Bhattarai, Eric Wikramanayake, and Michael Köhl "Conservation and Population Recovery of Gharials (Gavialis gangeticus) in Nepal," Herpetologica 73(2), 129-135, (1 June 2017). https://doi.org/10.1655/HERPETOLOGICA-D-16-00048.1

Maskey T.M. et al(2006), Gharial conservation in Nepal.Results of a population reinforcement program.