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Alien Fish Species Threaten India’s Freshwater Ecosystems

Alien Fish Species Threaten India’s Freshwater Ecosystems

Is an alien invasion underway in India? Experts are worried not only about the impact of exotic fish species on the native aquatic ecosystems into which they have been introduced, but also the over-harvesting of native fish for the ornamental fish trade. Unfortunately, a ‘Green Certification’ programme introduced in 2008 to promote and regulate aquarium fishtrade in the country has failed to address these concerns.

African Catfish Clarias gariepinus (for representational purposes only) Photo: Bernard Dupont/Public Domain.

S. Sandilyan, an expert on invasive alien species with the Centre for Biodiversity Policy and Law, notes in a review article in the journal Current Science that India has limited laws geared at the preservation of aquatic life - particularly in relation to the ornamental fish trade. As a result, there has been a proliferation of alien species that have negatively impacted native aquatic wildlife. Alien species diminish resources available to native fish, and can introduce unfamiliar pathogens into the ecosystems to which they have been introduced, which can cause disease among native wildlife.

The impact of alien invasive species is especially visible in the Yamuna riverine basin, where exotic species like the African catfish and the tilapia are proliferating. Worryingly, exotic ornamental fish have even been reported from the Chalakudy river in the Western Ghat, home to 16 endangered and four critically endangered species.

Sandilyan notes that alien species enter native ecosystems either through intentional release by hobbyists or during monsoon floods when they are swept out of their artificial breeding sites into natural water bodies. It is thus a matter of concern that over 200 alien fish species are bred in the country by local, untrained vendors.

A major loophole exists in that there is limited research in understanding the full effects of the damage caused by alien species. Currently, little legislation exists to prevent this damage, and existing laws can easily be bypassed. In 2008, a Green Certification (GC) was introduced to ensure that the alien species that were brought in did not carry diseases, and that the trade was sustainable in nature.  However, a commentary published in the June issue of Current Science notes that the current GC has “only very little constructive and positive suggestions and recommendations for the industry”. The problems include inconsistencies and contradictions within the guidelines, as well as discrepancies in terms of taxonomy and prioritization of species, which enables exploitative practices instead of preventing them.

The need of the hour is an immediate introspection into the arena of aquatic conservation, to prevent the devastation of the inland aquatic diversity of native breeds and species.

Sources: Current Science.


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