The Central Institute of Brackishwater Aquaculture (CIBA) has achieved a breakthrough in cage-farming of sea bass, commercially one of the most sought-after fish species, in the backwaters of Vennangapattu near Mamallapuram. Earlier, CIBA had experimented with cage-farming in Adyar Creek after the creek was cleaned, but only milk fish survived in the cages.
The success in Vennangapattu has increased the prospects for sea bass culture as it has proved to be a complete model. The technical assistance for fabricating the cages came from the National Institute of Ocean Technology (NIOT). Over 200 kg of fish, with their size ranging between 1 kg and 1.5 kg, were harvested on Friday and sold to the Tamil Nadu Fisheries Development Corporation.
In India, captive breeding of sea bass was achieved in 1997.
Since then the fish has been cultivated in ponds. But the advantage with cage-rearing of sea bass in brackishwater is that it belongs to the entire community of local fishermen and helps in augmenting their income. Pond culture benefits only individuals. “The fish catch is depleting in the sea and we have not utilized the potential of brackishwater area. Now lagoons and estuaries can be used for cage-farming without affecting the environment. As far as cage-farming is concerned, we have the complete technology including the food for the fish,” said K.K. Vijayan, Director of the CIBA.
Handsome profit
In Vennangapattu, Dr A.P.J. Abdul Kalam Fish Products Self Help Group managed the cage-farming and they sold their first harvest for ₹75,900. It will cost farmers ₹190 to rear fish up to 1 kg and the market value is between ₹350 and ₹400.
CIBA has designed cage-farming as a three-tier system. In the first phase, fish fry of 1 cm length is reared in the nursery for 45 to 60 days till they weigh five to six grams. They are then shifted to the pre-grow-out cage where they grow to 100 grams. Then they are shifted to grow-out cages.
The harvest is done once they reach the marketable size of 750 grams and above.
“We have to study the requirement of the market before going for a harvest. Otherwise farmers will not make profit. Normally we can harvest the fish two times a year. Here this is the second harvest,” said M. Kumaran, Principal Scientist of the CIBA and the head of the project in Vennangapattu.
R. Kirubagaran, NIOT scientist, said his team zeroed in on Vennangapattu after studying the nature of the waves there, wind speeds, water salinity and the depth of the backwater.
“The project can be successfully replicated in other backwaters,” he said.
M. Kailasam, principal scientist at CIBA, said unlike pond-farming, cage-farming requires less maintenance. “Since water flows from the sea, we need not monitor salinity on a regular basis and the fish adapt to the changes,” he explained.
