Illegal breeding of exotic marine species a threat to local varieties

Thinking that they have bought the fish at a reasonable price, they walk away, ignoring the actual sea catch. This is becoming common with illegal fish breeders dumping pangasius (freshwater sharks raised by breeders) and the pacu (mild reddish fish with piranha-like teeth) in the fish markets in and around Chennai. With pollution level increasing in the water bodies in South India, particularly along the Cauvery riverine and TN reservoirs, marine experts and scientists associated with the National Bureau of Fish Genetic Resources are concerned over the depleting freshwater biodiversity of Tamil Nadu and Kerala, and opine that more invasive species like the pacu and pangasius have made deep inroads into the country’s fish market. As a result, the indigenous varieties like kenda (carp), aiyira (spiny loaches) and veral (murrel) are affected and face habitat destruction.

“Several exotic marine species have encroached into the waterbodies across India and there is a need for baseline data and studies in this matter. There is also a lack of awareness and coordination between the stakeholders,” said Kuldeep K Lal, director, ICAR-National Bureau of Fish Genetic Resources.

Since the British era, as many as 463 fish species have been introduced and there are predators and omnivore categories threatening the survival of indigenous varieties. There is nothing wrong when these are raised for consumption, but releasing them into the wild is stated to be a serious offence that impacts the fish diversity and the economy around it. Tank cleaner (suckerfish) and Clarias gariepinus (African catfish) are classic examples of how they have entered our waterbodies and pose threat to the local fish varieties.

There is a need for eradication of these invasive species and the issues are at policy levels, explains Kuldeep Lal, who has close to three decades of experience in fish genetic resources.

There is a need for long-term solutions and public awareness about these fishes is very minimal. At present, NBFGS with the government is working on studies that explain the adverse effect these species pose and will soon give recommendations in this regard.

“Tank cleaners have completely made the Vaigai and Cauvery river bed devoid of fishes and freshwater fishermen are suffering a daily loss due to low catch, and it is very hard to eliminate these exotic fishes from Africa, Thailand and South America,” said a marine professor with the Tamil Nadu Dr. J. Jayalalithaa Fisheries University.