Scientists and conservationists have raised concerns over the efforts undertaken by the State Fisheries Department to introduce common carp into riverine ecosystems in the Nilgiris that host critically endangered species of fish like the hump-backed mahseer, arguing that introducing potentially invasive species could have catastrophic consequences for local ecology that inhabit the Nilgiris’ pristine rivers.
The carp are being introduced to restock rivers under the Pradhan Mantri Matsya Sampada Yojana, said N. Jothilakshmanan, Assistant Director of Fisheries (Nilgiris district). The fish were being introduced to the Kamaraj Sagar Dam, Pykara Lake and Glenmorgan in the Nilgiris, added Mr. Jothlakshmanan.
However, scientists and conservationists working on preserving river ecosystems have criticised such efforts, arguing that the introduction of species like the carp, which had become invasive in many parts of the world, could threaten highly endemic, endangered aquatic flora such as the Nilgiri danio, Nilgiri barb, Bowany barb and the critically endangered hump-backed mahseer.
The Kamaraj Sagar Dam, Pykara and Glenmorgan are all part of river systems that eventually flow into the Moyar River, home to a huge variety of native and endemic biodiversity, which, many fear could be impacted if it became overrun with invasive species.
Dr. Vidyadhar Atkore, scientist at the Salim Ali Center for Ornithology and Natural History, who has been working on studying freshwater biodiversity along the Moyar River over the last few years, told The Hindu there had been multiple instances when common carp had become invasive species in river ecosystems across the world. “The proliferation of these fish could be catastrophic if they escape downstream and into the Moyar,” said Dr. Atkore, stating that in most cases, the Fisheries Department released fishlings in rivers and dams without the approval of the Forest Department if the streams or dams were under their jurisdiction, which would make putting a stop to such initiatives difficult.
“These common carp grow rapidly, proliferate in large numbers and forage heavily. So wherever you release them, they have the potential to create havoc. So, studies are required to understand the damage that they wreak on the local flora and fauna,” he added.
“The Moyar is a highly endemic-species rich river in Tamil Nadu. There are critically endangered species like the mahseer, and the population of such species are already highly fragmented because of dams along the river ecosystems they inhabit and pollution. Introducing other non-native, potentially invasive species that could out-compete native fish could pose an additional risk to their survival,” added Dr. Atkore.
Another conservationist, working on conserving the hump-backed mahseer, who requested anonymity, said there had been a surge in releasing species like carp and catla in rivers and dams across India. “Though these species do compete with native fish species, they aren’t as dangerous as other introduced species like the African catfish or the armored catfish,” he said, adding that the Moyar was one of the last untouched habitats for the mahseer, and that the Fisheries Department should set up isolated ponds or dams where there was no potential for species to escape into native river ecosystems.
Responding to the concerns raised by conservationists, Collector M. Aruna said neither the Forest Department nor Fisheries Department had informed her of these concerns of the restocking of carp into dams in the Nilgiris. “I will order a review into the programme and look into it,” said Ms. Aruna when contacted by The Hindu.
