Devdatta Lad
Abstract
Invasive species are ânon-indigenous species that spread from the point of introduction and become abundant.â The invasive species cause damage to the endemic species in the ecosystem. The invasive fish species cause direct and indirect harm to the native species. The direct harm includes the predation of the native species, competing with the native species for food and other resources, causing or carrying diseases, and preventing native species from reproducing or killing the young ones. The indirect threat of invasive species includes changing the food web in an ecosystem by destroying or replacing native food sources. Invasive species can also alter the abundance or diversity of species that are important in the habitat for native wildlife. The Zoological Survey of India reported that inland wetlands alone support 1027 species of fish with more biological, nutritional, and economic value. The National Biodiversity Authority of India has recognised 14 freshwater invasive species in Indian freshwater ecosystems. The invasive fish species are Clarias gariepinus, Cyprinus carpio, Gambusia affinis, Gambusia holbrooki, Mylopharyngodon piceus, Oreochromis mossambicus, Oreochromis niloticus, Poecillia reticulata, Pterygoplichthys disjunctivus, Pterygoplichthys multiradiatus, Pterygoplichthys pardalis, Pterygoplichthys anisitsi, Pygocentrus nattereri, Aristichthys nobilis. These 14 freshwater invasive species recognised by the National Biodiversity Authority of India in Indian freshwater ecosystems are exhibiting invasiveness elsewhere, rapid multiplication and spread in different ecosystems, multiple modes of reproduction, and multiple modes of dispersion. These are leading to effects on ecosystem functions and services, biodiversity loss, economic loss, health hazards, and also range extension. Looking into the seriousness of the issues, control and remedial measures should be implemented. Regulation must be brought on unauthorised culture. Aquaculturists and aquarists should take measures so that cultivable exotic food fish cannot enter the open water body. For the same, awareness programmes to educate aquaculturists and aquarists need to be conducted to educate them about not releasing the cultivable exotic food fish into natural waterbodies. Proper quarantine is urgently needed before introducing new species for any purpose, like aquaculture, ornamental, sports, or to control mosquito populations. These control measures will surely protect the Indian freshwater fish biodiversity against the detrimental effects of invasive freshwater fish species.