MANGALURU: Release of nearly 10,000 non-native fishlings into the Kumaradhara river in the ecologically sensitive Western Ghats has drawn flak from aquatic experts, who fear the move could threaten the region’s native and endangered fish species.
Common Carp and Major Indian Carp (Catla) were released into the river on November 4 by a group of political activists in the presence of gram panchayat officials. This move is aimed at improving fish stocks and supporting local fishermen.
Experts point out that Kumaradhara, a tributary of the Netravathi, supports nearly 90 species of fish, including several that are endemic to the Western Ghats such as dwarf puffer fish (Carinotetraodon imitator), Canara pearlspot (Etroplus canarensis) and Harobagrus brachysoma catfish. The introduction of non-native species may gradually alter the ecological balance and threaten native biodiversity.
The Fisheries Department, which supplied those fishlings, defended its action. However, aquatic scientists warned that such interventions may disturb the natural riverine ecosystem.
Dr Shivakumar Magada, professor, Aquatic Biology, College of Fisheries, Mangaluru, said the release of exotic or non-native species into the natural water systems is not advisable.
“Common Carp and Major Indian Carp may not prey on native species, but they compete for food and space, disrupting the food chain in a low-productive system,” he added.
He said instead of non-native fish species, indigenous ones such as ‘Carnaticus’ and ‘Mahseer’ could be released under the guidance of fisheries officials. “What has been done is not condemnable. It is not ecologically advisable,” Dr Magada added.
Expressing concern over such issues across the country, conservationists and environmentalists said the authorities should frame scientific guidelines for fish rearing in rivers. Only native species bred in approved centres should be released, particularly in biodiversity-rich regions such as the Western Ghats.
Joint director of Fisheries, Mangaluru, Siddaiah, said there is no harm in releasing Common Carp and Catla into rivers. “Both are freshwater, herbivorous species and do not compete for food or space with native species,” he added. “We have been releasing them into rivers and reservoirs across the state, including KRS and Almatti, to improve fish catch and help local fishermen. The department routinely undertakes such stocking programmes in inland water bodies,” he said.