An International Team Working To Identify The Suspected Toxin And Its Source, Which May Have Caused At Least 101 Gharial Deaths.

National Chambal River Sanctuary, India. Press Release from Gharial Conservation Alliance/February 20, 2008/www.gharials.org

Indian government officials and an international collaboration of researchers and laboratories continue the investigation into the deaths of at least 101 critically endangered gharial in the National Chambal River Sanctuary.

Starting the last week of January, specialists began arriving in the Chambal from around India and the world to investigate the deaths.

The team included members of the Uttar Pradesh and Madhya Pradesh Forest Departments, the IVRI (Indian Veterinary Research Institute), Wildlife SOS, Aniruddha Belsare, the GCA veterinarian, Fritz Huchzermeyer, Vice Chairman (Veterinary Science) of the IUCN Crocodilian Specialist Group (IUCN-CSG), Paolo Martelli from Ocean Park (Hong Kong), Samuel Martin from La Ferme aux Crocodiles (France), and Brian Stacy from the University of Florida (USA), who are also part of the IUCN-CSG Veterinary Advisory Group.

The team conducted necropsies (post-mortem examinations of dead animals) on several gharial and ruled out the possibility of any infection or parasite as the cause of death. All dead gharial were diagnosed with kidney damage and failure, significant gout within the body cavities and around internal organs (visceral gout), and gout within the joints articular gout). Gout is a disease that causes severe arthritis and pain due to toxic build-up of uric acid within the body.

The dead gharial have appeared otherwise healthy and fat, indicating the problem is relatively recent. Gout around the heart can interfere with normal heart function, and kidney failure ultimately leads to death. The kidney damage and failure most likely was caused by an unidentified toxicant, the team has determined based on microscopic changes in the kidneys of the dead gharial. The gout has caused the affected gharial to be unable to move properly, even to move out of the water, and witnesses have observed gharial „spinning around‰ in the water as though unable to stay afloat properly. Within 2 days of showing this symptom the animals die.

Gharial, like all crocodilians, are ectothermic, meaning they rely on the external environment to regulate their body temperature and maintain normal body functioning. They must go into the water or shade to lower their body temperature or onto land to sun themselves in order to raise their body temperature. There have been record low temperatures in the Chambal region recently, so the inability of affected gharial to move themselves out of the water to warm their bodies will have also negatively affected the health of the animals.

The team is conducting tests to to determine if a toxin is responsible for the deaths, and results are expected soon. Investigations into the source of a suspected toxin are continuing. It is unknown whether the deaths are due to a single event or a continuing cause. Careful monitoring of the region is essential and is ongoing. The initial cause of the problem, such as a release of toxins into the system, is estimated to have occurred 2-6 months before the first week of December, when the first gharial deaths were recorded.

It is unclear why the gharial appear to be the only animals noticeably affected thus far, and why only a select age and size of gharial are affected (between 160-410 cm in length), or why the vast majority of the deaths were centered in a 35 km segment of the 425 km of the Chambal River where gharial are found. One Ganges River Dolphin was recently found dead and several fish die-offs in the nearby Yamuna River were recorded in 2007, however neither of these events has yet been definitively linked to the gharial deaths. No other deaths of plants or animals have been observed in the Chambal River.

Evidence suggests that if a toxin was the ultimate cause of the kidney damage in the gharial, either it was dumped into the Chambal or the nearby heavily polluted Yamuna River, or entered the gharial through the food chain. Fish inhabiting the Chambal and Yamuna Rivers will be a focus of further investigation, as will industrial and other human activities in the region. One possibility is that a toxin has accumulated in various fish species fed upon by the gharial.

The last gharial death was recorded on February 11th and it may be possible that a very recent increase in the daytime temperatures is slowing down the death rate. It is hoped the deaths will soon cease and this fragile gharial population can begin to recover. However gharial face many other threats, and this recent crisis highlights the urgent need for careful monitoring of this unique species and its river habitat.

For further information or to contact the GCA see the GCA website www.gharials.org
Contact: Laurel Converse, GCA Executive Officer