While the aquaculture scene in the State is flourishing, fish species introduced for the purpose may pose a serious threat to indigenous biodiversity. Fish escaping from enclosures to open systems, mainly due to damaged netting or extreme climatic events like floods, often invade the habitat of native species, causing a dip in their population.
According to experts, many exotic species were released to Kerala waterbodies during the floods of 2018 and their numbers must have soared over the years. Farmed for their impressive growth rate, these fish can alter the aquatic ecosystem by competing with the native species and displacing them. Post-flood field surveys carried out by Kerala State Biodiversity Board had revealed the presence of alien species in the State’s major river systems and associated backwaters. It included high-risk species like Arapaima ( Arapaima gigas) and Alligator gar ( Atractosteus spatula) along with some aquarium varieties that are not permitted to be imported to the country.
A variety of anabas is now very popular among aquaculturists and inland fishers complain that the extensive cultivation is affecting the native stock. “It’s not the local variety as the authorities claim and they are changing our fishery pattern. They are also invading our wetlands depleting the stock of species like snake head and pearl spot,” says Gopi, a fisher from Alappuzha.
