Contaminated fish killing gharials in Yamuna

By Brij Khandelwal, IANS

Agra : Alarm has been raised over the death of 90 gharials in the Yamuna river recently after eating contaminated fish, says an expert from the The International Union for the Conservation of Nature and Natural Resources(IUCN) after studying what killed these critically endangered animals.

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Crocodile expert Fritz Huchzemeyer said the gharials that died near the confluence of the Yamuna and Chambal rivers could have damaged their internal organs after eating tilapia and the Japanese fugu – fish that contained high concentration of pollutants.

These two fish species thrive in polluted waters. Toxins like lead accumulated in their body can be lethal if the fish are eaten, especially as lead concentration increases up the food chain.

The gharial (Gavialis gangeticus) is one of two surviving members of the family Gavialidae, a group of reptiles, closely related to crocodiles, but with longer, narrower jaws.

The gharial has been placed among critically endangered animals in the IUCN’s 2007 Red List of Threatened Species. Even before the latest deaths, its population had declined from 436 breeding adults in 1997 to just 182 in 2006.

Before the poisoned fish, dams, irrigation projects, sand mining and artificial embankments have threatened their existence as they could not move along the rivers as before.

Fritz, who carried out extensive surveys along the Yamuna river, said that the abundance of tilapia and pollutants at a particular stretch of the river were responsible for the deaths of the gharials.

In his report, Fritz, who is the vice-chairman of the veterinary advisory group of the IUCN (Croc Specialist Group), said: “Toxin was found on the skin of the fishes that were consumed by the gharials.”

Tilapia is a killer fish that preys on other fish and other aquatic wildlife. “The fish perhaps escaped from some ponds and are now reproducing rapidly in the Yamuna waters,” an official said.

But the fishermen of the area are disappointed as they are not able to catch other varieties of fish. “With no fresh water in the river, tilapia is the only fish that can survive, as it is pollution resistant. However, the problem is there are no buyers for this fish,” a fisherman added.

Commercial use of this fish is banned in the state. “Only for research purposes people are allowed to breed the fish in ponds,” a fisheries department official said.

The fear is that the fish may soon spread to other parts of the river system and in the long run may reach the Ganges and eventually into the Bay of Bengal, a fisheries expert said. The government should therefore act fast, he added.

Fugu, a strange and colourful looking fish of Japanese origin, was found by a fisherman in the Yamuna last week and is currently the subject of discussion among the fishermen in Agra. It is considered one of the deadliest fish in the world.

Environmentalists in Agra have raised alarm after the discovery, as the fish could endanger human health and aquatic wildlife.

The IUCN is the world’s largest conservation network, which brings together 110 government agencies, more than 800 non-governmental organisations (NGOs), and some 10,000 scientists and experts from 181 countries in a unique worldwide partnership.