New Delhi (PTI): Toxins prevalent in polluted Yamuna river have taken a toll on crocodiles of Chambal region in Uttar Pradesh, according to an international crocodile expert Fritz Huchzemeyer.

Though the toxin responsible for the death of the crocodiles is yet to be identified, Fritz, who visited the site of mortality in the region, held African fish Tilpia found abundant in the region as a carrier of the toxin. The high toxin content damaged the endangered species' kidneys, resulting in renal failure and finally their death, Huchzemeyer suggested in a report.

"The toxin is accumulated on the skin surface of the fish which are consumed by the crocodiles," the vice-chairman of IUCN-Croc Specialist Group's veterinary advisory group said in the report.

He emphasised on the need to look into the toxins contents in Yamuna through the Yamuna Action Plan which is being implemented to cleanse the polluted river. In the past two months, around 93 ghariyals have died mysteriously, prompting the officials to send a team of experts to probe into the deaths.

Most of gharial mortalities have been reported in the Uttar Pradesh side of the river, near the confluence of the Chambal and the Yamuna that flows through Delhi and Agra. Crocodiles have been enlisted as critically endangered species by the World Conservation Union.

According to the expert, other animals including alligators (muggers) were unaffected to the toxins since their food diet included other animals such as frogs, other species of fishes besides Tilapia. "However, since Tilapia are the main diet of the crocodiles, they were the most affected," he said and suggested further investigations to identify the fatal toxin responsible for the death of the fresh water species.