By Sanjaya Jena, Bhubaneshwar
Wildlife officials in India's eastern state of Orissa are to use satellites to track endangered crocodile-like gharials released into the wild.
Gharials feed mainly on small fish (Photo: Ajit Patnaik)
They say only a few of the 501 gharials set free since 1986 have survived.
By monitoring the reptiles, staff at Nandan Kanan zoo near Bhubaneshwar hope to find out what happens to them.
The gharial, with its distinctive long, narrow snout adapted for eating small fish, is facing extinction in many parts of South Asia.
For the past 20 years, staff at Nandan Kanan zoo have been rearing gharials and releasing them into the Mahanandi river at two points - Satakosia and Tikarpada in Angul district.
But very few of the crocodilians have survived. It is not clear why.
Experts believe the gharials are unable to cope with the change in their water habitat when they leave the zoo.
Other factors such as fishing and pollution of the river by industrial effluents are thought to have contributed to the decline in the number of gharials.
Ajit Patnaik, director of Nandan Kanan zoo, says he hopes the satellite tracking plan will help halt the gharials' decline.
"The wildlife wing - in its fresh bid to save the species from extinction - now proposes to release the [gharials] in the wild but only after a thorough habitat survey and a post-monitoring programme," he said.
He said he wanted the Wildlife Institute of India (WII) to carry out a habitat survey of the Mahanandi river.
The gharial, or Gavialis gangeticus, is one of the longest of all living crocodilians - an adult male can approach 6m in length.
It has already disappeared from major rivers such as the Brahmaputra and the Chambal, and is no longer found in Pakistan, Myanmar and Nepal, wildlife activists say.
But Nandan Kanan currently has no shortage, with 25 adults and more than 40 juveniles of different ages. Fifty hatchlings have been added to the list over the past two months.