Sunday, 15 March 2009
Where have the gharials gone?
Once common throughout its range with an inferred population of 5,000 to 10,000 in the 1940s, the gharial numbers have gone gone down to less than 200 breeding adults.
When more than 100 gharials died in the Yamuna and Chambal rivers in India last year, it sent alarms among the conservationists and people started identifying gharial as one of the most threatened crocodilian species.
Croc with a pot on its snout
The gharial (Gavialis gangeticus) is characterized by its long and slender snout and mostly inhabits deep, fast-flowing rivers. Its name derives from the cartilaginous protruberance at the end of the adult male’s snout that resembles a Ghara, an earthen pot common to India and Nepal.
It is the only crocodile species in which the male is morphologically different from the female. The gharial, like other crocodiles, helps bring nutrients from the bottom of the riverbed to the surface, thus increasing primary production and fish populations and helping maintain the aquatic ecosystem.
Gharial is the first crocodilian species to be re-categorized as Critically Endangered on the 2007 IUCN Red List. It was common throughout its range with an inferred population of 5,000 to 10,000 in the 1940s.
Dr. Narendra Babu Pradhan, the Chief Warden of Chitwan National Park said, "During the period of 1981-2008, 691 gharials were released in Narayani, Rapti, Karnali, Babai, Koshi and Kali Gandaki rivers."
However, gharial numbers continue to plummet. A 2008 survey confirmed the presence of 81 individuals in the different rivers of Nepal, the number presumably higher due to the release of captive-bred gharials.
Radio tagging to track the movement
Fourteen radio tagged gharials were released in a make-shift enclosure at Dumariya ghat of the Rapti River. The duo of Dr. Antoine Cadi and Renan Aufray from the French NGO, Awely, helped the team from Chitwan National Park (CNP) to fit the gharials with radio transmitters.
The transmitters are attached to the scutes on the gharials' tails and each gharial has been provided a different number and radio frequency. They will be monitored based on Radio Frequency Identification (RFID) technology by the team of CNP staff led by Bishnu Thapaliya and Madhav Khadka.
WWF's Country Representative to Nepal, Mr. Anil Manandhar said, "The study will help in diagnosing the causes of decline in the gharial population. It will also help us better understand the gharial’s habitat use — knowledge crucial for saving the most threatened crocodile in the world."
“Although conservation efforts such as the tagging and release of gharials are important steps in saving the species, a lot more is needed to ensure its long-term survival. Integrated efforts that include captive breeding, research and monitoring, and especially safeguarding gharial habitat and prey, are urgently needed, “ added Sarala Khaling, regional co-ordinator of the Critical Ecosystem Partnership Fund, which has largely funded this release and monitoring project.
Closer to extinction
Although hunting is no longer a threat to the species, the construction of dams, barrages, irrigation canals, sand-mining and riverside agriculture have all resulted in the irreversible loss of habitat for the gharial. The river pollution and overfishing have added to the woes of these crocodiles.
The gharial is now considered to be confined within the river systems of the Brahmaputra (India and Bhutan), the Indus (Pakistan), the Ganges (India and Nepal), and the Mahanadi (India), with small populations in the Kaladan and the Irrawady in Myanmar.
" The water quality of Nepalese rivers are better suited for gharial's survival," says Dr. Cadi. "If not saved in Nepal, they will be closer to extinction."
The monitoring of the released gharials will be helpful in formulating a long term conservation action plan to save these critically endangered species.