Mass Gharial Deaths in Chambal
January 1, 2008
The population of gharial crocodiles (Gavialis gangeticus) has recently suffered a serious blow. Since early December more than more than 65 gharials have been found dead within a 35km stretch of the Chambal River, which runs through the Indian states of Uttar Pradesh, Rajasthan, and Madhya Pradesh. Though there are several hypotheses as to the cause of the deaths, to date there is no definitive diagnosis and investigations are continuing. The Chambal River gharial population is the largest of only 3 remaining breeding populations of gharial left in the world. With estimates from 2007 population surveys indicating 200-300 breeding adults left in the world, the recent mass deaths pose
a significant threat to the species.
On December 9th Dr. Rajeev Chauhan of the Society for Conservation of Nature (ScoN), an NGO based near the Chambal River, received the first reports of two dead gharials in the village of Kasaua in the National Chambal Sanctuary (NCS). Upon investigating these reports Dr. Chauhan and Forest Department officials found 5 gharial carcasses in NCS. The Gharial Conservation Alliance (GCA) was informed and began mobilizing a response.
Over the next few weeks more gharial carcasses were found in NCS, and the known death toll currently stands at 67. All dead gharials have been sub-adults and young adults (5.5-10 feet long), no mortalities of juveniles have been reported. The sex ratio of the deceased gharials has not been definitively determined, but a significant number are believed to have been males. There have been no reports of deaths in other river wildlife. The dead gharials had no external physical signs of injury, and necropsy results indicated deaths were not due to drowning in fishing nets, one of the most common causes of mortality in gharials.
Several gharial necropsies (autopsies on deceased animals) have been performed by the Indian Veterinary Research Institute (IVRI), the Veterinary College Jabalpur and ITRC. Unfortunately most of the gharial carcasses found were significantly decayed, making post-mortem diagnosis difficult. A preliminary report by IVRI concluded the cause of death was failure of the liver and kidneys due to damage caused by a protozoan parasite (Klossiella species). Concentrations of lead and cadmium were also found in the gharials, however these levels were not high enough to have been directly responsible for the gharial deaths. Gharial researcher Dr. RJ Rao, of Jiwaji University, has stated that
protozoan and helm ith parasites are fairly common in gharials and other reptiles they have studied, and do not usually cause mortalities. Their previous studies of Chambal River water quality and local fish have not revealed any heavy metal contaminants or other significant pollution. Recent water samples sent to several research institutions in Madhya Pradesh and Uttar Pradesh have not revealed any sources of toxicity or pollution in the area where the gharials have been found. However this does not rule out the possibility of gharial feeding on fish contaminated with toxins or pathogens that may migrate from the heavily polluted Yamuna River, which joins the Chambal at the sanctuary’s lowest extremity.
Other hypotheses for the deaths have also been suggested. After reviewing gharial necropsy photos and case facts Dr. Fritz Huchzermeyer, a South African crocodilian veterinary specialist, has suggested the deaths may have been caused by Pansteatitis, a condition caused by consumption of rotten fish. Dr. Huchzermeyer, who is the Vice Chair of Veterinary Science for the World Conservation Union Crocodile Specialist Group (IUCN-CSG), said Pansteatitis has caused mortalities in South African crocodiles after a fish-die-off. The condition causes hardening of the crocodile’s fat, leading to decreased mobility of the animal, and ultimately death by starvation 6-8 weeks from consumption of the fish. The fatty degeneration of the liver tissue caused by this condition can appear similar to the signs of cirrhosis, which may account for preliminary diagnosis of cirrhosis in the dead gharial. The most significant post-mortem sign of Pansteatitis is deep yellow to orange-colored fat. IUCN-CSG Chairman Dr. Grahame Webb has officially urged participation of the IUCN-CSG Veterinary Committee in the investigations and response to this crisis.
The Gharial Conservation Alliance is working with Forest Department Officials, Indian researchers and veterinarians, the IUCN-CSG, Worldwide Fund for Nature-India (WWF- India), Wildlife Institute of India, and crocodile and veterinary experts from around the world to find the cause of this devastating die-off and take immediate action. GCA researcher Dhruva Basu is currently in the Chambal River working with local officials and veterinarians to investigate the crisis. The team is taking samples from live gharial in the area, particularly those that may appear sick, as well as sampling other flora and fauna, for more clues on the cause of the mortalities. One 3 meter female gharial that is in an advanced stage of the disease has been corralled and is being experimentally treated with a combination of antibiotics, liver supplements, pulmonary stimulants and cortisone. West Asian Regional Chair of the IUCN-CSG, Mr. BC Choudhury, is conferring with international and national authorities about this crisis. At the behest of WWF-India the Ministry of Environment and Forests will be hosting a meeting in Delhi with the GCA,
government officials, veterinarians, and all involved parties to review evidence and formulate a plan of action. The Principle Chief Conservator of Forests in Madhya Pradesh, Dr. P.B. Gangopadhaya, has sent a letter to the Indian Ministry of Environment and Forests urging immediate action and suggesting this be declared a national conservation emergency.
Vigilant monitoring of the Chambal River and thorough investigations into possible causes must be continued.
Those wishing to contribute to the Chambal Gharial Crisis Response financially or otherwise can CONTACT US here