The Rajiv Gandhi Centre for Aquaculture (RGCA) has produced the first-ever neo-female scampi, which can produce 100 per cent male progeny

A low-profile scampi – giant freshwater prawn -- research centre has achieved a ground-breaking result that promises doubling of the output of this prawn variety in farmers' ponds.

Scientists at the Rajiv Gandhi Centre for Aquaculture (RGCA) are overjoyed over the success of the production of the first-ever proven neo-female scampi, which can produce 100 per cent male progeny from the majestic animal.

Project Manager S. Vijay Kumar and Assistant Project Manager D.V.S.N. Raju told The Hindu that they did not stop at that and went on to produce another couple of neo-females that were giving all-male progeny, but before they announced to the world that they could handle it on a commercial scale, a lot more dedicated work by a team of biologists has to go into the effort.

Researchers at the facility set up in 2006-07 to work on production of scampi (Macrobrachium rosenbergii) brood stock achieved success in the third week of April 2011, but were reluctant to give it publicity lest farmers mistake them to be suppliers of scampi seed. Commercial availability could take yet another two years.

Partners

“The Ministry of Commerce and MPEDA are partners in this effort and propose to register the Intellectual Property Rights over this invention and later decide on a business model to transfer the technology to some hatcheries, which could produce 100 male seeds for supply to farmers,” said Mr. Vijay Kumar. The only other country that could produce successfully is Israel with field trials in Vietnam.

Farmers now painstakingly resort to hand-segregation of male prawns at the farm level to rear them on a mass scale as each male scampi grows to 150 gm in a season of eight to nine months, compared with 50 gm for female.

Sex reversal

Normally, on an average, 50 per cent are female, but with microsurgical intervention robust freshwater prawn strains were chosen from West Bengal, Kerala and Gujarat and sex reversal was achieved on healthy males into ‘functional females' also called neo-females at 35 to 45 days of post-larval stage. These neo-females are crossed with normal males to get 100 per cent male progeny.

Researchers

Leading the research at the laboratory is Mr. Raju along with Johny T. Varghese and at the field level B. Appalanaidu takes care of rearing them. Removal of androgynous glands forms the key to the process and stringent post-surgery quality control. Laying of eggs (spawning) takes place 10 to 15 times in controlled conditions, compared with 12 to 15 times in their lifespan of six years.