Home Magazines Conservation Bharatpur Authorities Battle Catfish Invasion

Bharatpur Authorities Battle Catfish Invasion

Bharatpur Authorities Battle Catfish Invasion

In Rajasthan’s Keoladeo National Park, aquatic and avian fauna are threatened by the African catfish Clarias gariepinus, an invasive species that has rapidly come to dominate the park’s waterbodies. Stuti Pachisia outlines the eradication effort currently underway.

Piles of invasive African catfish removed and left on the grounds of the park to be eaten by scavengers. Photo Courtesy: Forest Department, Keoladeo National Park.

The introduction of exotic species is enormously easy, and in many cases their impact on natural ecosystems is dire. Introduced species are often hardy and can create ecological competition where competition did not previously exist, consequently disrupting ecological balances. In the case of introduced predators, native species are not adapted to face them, thereby becoming easy prey. This phenomenon is pervasive in India’s aquatic bodies – to the point that zoologist and ecologist, S. Sandilyan noted in a review article for the journal Current Science that ‘recent studies in several parts of India have highlighted the fact that freshwater fish biodiversity is depleting at an alarming rate due to invasion of commercially important and ornamental, exotic fish species’.

The African catfish is a particularly formidable foe to India’s native wildlife. It is a hardy, widely-distributed fish from Africa that was introduced in South and South-East Asia for the purpose of pisciculture. The resilience that makes the fish economically beneficial is what makes it environmentally hazardous. Not only can the African catfish thrive in extreme environmental conditions, it can also crawl over ground to colonize nearby water bodies. The fish breeds in the rain, and its eggs take only two-three days to hatch - for which even a brief bout of rain is sustainable. Sexually mature females can lay tens of thousands of eggs, and, most dangerously, as the Action Plan for its extermination from Keoladeo notes, “the species is omnivorous in feeding habits, feeds largely of fish, insects and crustaceans, known to attack healthy animals and also influences distribution and feeding of other fish (Teugels, 1986). In recent years, even water birds and terrestrial birds have been recorded in the diet of the African Catfish (Anoop et al., 2009).” As a voracious predator that often hunts in packs, it has an edge over most native species, which have not adapted to deal with this alien predator.

Catfish infestation in Keoladeo National Park. Photo Courtesy: Forest Department, Keoladeo National Park.

The need to rid the National Park of the species comes with weighty immediacy. In 1997, the Ministry of Agriculture issued directions to all state governments and union territories vide letter No. 31015/1/96 FY (5) to take urgent steps to destroy the existing stock of introduced African Catfish without official sanction. In accordance, a task force was constituted for “the Control and Eradication of African Catfish”, and Operation Mangur (the local name for the African catfish is mangur) was launched in Keoladeo National Park. This task force includes the director of the park, Bijo Joy, the renowned ornithologist Bikram Grewal and the acclaimed wildlife conservationist, Dr. Gopi Sundar.

Last year, park authorities destroyed a staggering 40,117 African catfish under Operation Mangur. After a thorough reconnaissance of the area, parkstaff, rickshaw pullers and members of Life Line for Nature Society, a local NGO, were trained to identify and differentiate between indigenous and invasive species of fish within the infested water bodies. Native species were then temporarily relocated to a separate site, while the infested waters were pumped out in order to expose the catfish. Then, by fixing iron mesh gates, manually removing the invasive species with fishing nets, and isolating ponds, the catfish were removed. The collected catfish were either dumped at different points in the Park, away from water bodies, or buried. As the law bans the commercial exploitation of any produce from a National Park, the disposal of all African catfish was carried out within the Protected Area. Authorities observed the dumped fish being eaten by jackals, hyenas, vultures and other wild scavengers.

The skeletal remains of a bird were found in the stomach of catfish, revealing the severe threat they pose to Keoladeo, a bird haven. Photo Courtesy: Forest Department, Keoladeo National Park.

Operation Mangur is not a one-off attempt. The current action plan is devised for ten years in order to completely eliminate catfish from re-entering the water bodies, and will continue till 2026. This long-term effort is critical as the catfish is a superbly adaptable and stubborn species that can easily survive half-hearted eradication attempts. Therefore, post- operation information and follow-up is necessary. Alongside interventions such as the installation of sluice gates to prevent the catfish from moving from one block to another, other measures such as the annual tilling of dried wetlands have to be taken. Bijo Joy, Field Director of Keoladeo National Park and the man who is spearheading Operation Mangur, asserts the seriousness of the problem. He says, “This year's activities under Operation Mangur ended on June 23, 2016. As per the State Wildlife Board, our team treated every waterbody in the park, including D block which was left out last year. In Keoladeo, we have recorded the catfish eating birds like moorhens, bee-eaters etc. As per the directives of the Government of India, the rearing and import of African catfish is banned, and we hope that with our sustained efforts will be able to completely eradicate this exotic, carnivorous fish from the park.”

Eliminating the African Catfish is crucial to the health of Keoladeo National Park, which despite being just 28.7 sq. km. in size, is recognized as a World Heritage Site, Ramsar Site, and Important Bird Area. While the threat of the catfish invasion still looms large, battling ‘alien invasives’ is not new to the park management, which has earlier successfully removed the invasive plant Prosopis juliflora from the park – a comforting thought for the nature-lovers who consider Keoladeo a mecca for birding.

Stuti Pachisia, a wildlife enthusiast, studies English at Lady Shri Ram College for Women. She is currently an editorial intern at Sanctuary Asia.

Read more on the issue here: Alien Fish Species Threaten India’s Freshwater Ecosystems


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