PA Update April 1, 2008
As of March 29, 2008, 111 gharial (54 males, 48 females and 9 unknown) have been found dead on the Chambal. The first report of the mass die-off was received on Dec 8, 2007. The mortality was limited to the lower 40 kms of the National Chambal Sanctuary, the stretch closest to the Yamuna, killing about 33% of the adult/sub-adults (between the sizes of 1.6 m and 3.5 m). There are an estimated 1130 gharial found in 4 populations in India, of which nearly 1000 were counted in the Chambal during the survey of 2008.
During the initial days of the investigation, parasite overload and heavy metal concentration in the internal organs were bandied as the possible causes. However, these were subsequently ruled out by international crocodile veterinarians. The Ministry of Environment and Forests instituted a Crisis Management Group headed by Ravi Singh, the CEO of WWF-India. Post mortems conducted by experienced crocodile vets revealed visceral and articular gout, caused by kidney failure. What caused this is still a matter of speculation. Toxins in the ecosystem, perhaps in the fish or in the environment, is an avenue of investigation. The other speculation is that the gharial may have indulged in gluttony until their metabolism could not handle it anymore in the cold winter months, leading to gout.
Although the National Chambal Sanctuary is a 428 km stretch of river, the gharial live in 4 main groups. The affected area is close to one of the large groups and the incident may have wiped out a majority of the adults/sub-adults of this area. However surveys of 2008 reveal that this is not a static system allowing the incident to be isolated. Instead, animals were seen moving downstream to occupy the area vacated by the dead gharial. In 2007 surveys revealed that the affected area had 153 adults/sub-adults, while in 2008, the same area has 128 adults/sub-adults. So this stretch of river could become a sink for the Chambal population.
Crocodile biologists say that it is critical to monitor nesting this year to assess reproductive success. Loss of fertility may indicate continued toxin presence. The future course of action is to conduct extensive toxicology tests to identify the lethal toxin and its source, and studies on gharial behavioural ecology.
The various organizations involved in the operation to get to the bottom of the crisis are:
1. Ministry of Environment and Forests, Government of India
2. Forest Departments of Uttar Pradesh (UP) and Madhya Pradesh (MP)
3. RiverWatch – a joint initiative of Gharial Conservation Alliance (GCA) and Worldwide Fund for Nature-India (WWF)
4. IUCN/SSC Crocodile Specialist Group
5. The San Diego Zoological Society
6. AZA Crocodile Advisory Group, (USA)
7. Ocean Park, Hong Kong
8. Madras Crocodile Bank/Centre for Herpetology, Chennai
9. La Ferme aux Crocodiles, France
10. Wildlife SOS, Delhi and Agra
11. University of Florida, Gainesville
12. The City University, Hong Kong
13. Indian Veterinary Research Institute (IVRI), Bareilly
14. Defence Research and Development Establishment, Gwalior