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Use of "green water" technology boosts shrimp farming

by Don P. Lejano



After three years of research, shrimp producers are now enjoying the benefits of using green water technology as biocontrol agent in prawn grow-out culture.

Spearheaded by Dr. Jesse D. Ronquillo of the National Institute of Molecular Biology and Biotechnology and Prof. Valeriano L. Corre, Jr. of the Institute of Aqualculture (IA), College of Fisheries and Ocean Sciences from the University of the Philippines in the Visayas, the biotechnology effort on the green water technology was started in 1999.

The project was aimed to develop a technology which will help prevent and control aquaculture diseases like the spread of vibrio or luminous bacteria. An outbreak of this disease occurred in 1993 which caused high mortalities and termination of grow-out activities in many shrimp farms in the Visayas.

Different solutions have been identified to control the outbreak of the luminous bacteria in the prawn grow-out ponds.

Chlorination has long been used a means of reducing pathogens in the water but it was proven to have a short-term effect and rapid repopulation of seawater occurred upon dechlorination. Another identified method of controlling diseases in the water was the use of vaccines and antibiotics. However, vaccines are not available for most diseases in aquaculture and the use of antibiotics is rather controversial due to the effects these could have when consumed by humans.

Modifications in management techniques were even suggested to address the issue of the luminous bacteria outbreak. The use of semi-intensive farming method and the use of modular ponds were some of the suggestions but they were proven to be rather expensive and laborious.

Since the completion of Dr. Ronquillo and Prof. Corre's project in 2002, shrimp production has been enhanced due to the development of a farmer-friendly technology.

The new developed technology is the use of green water to culture shrimps. Green water technology is a technique that uses phytoplankton-rich water. In this system, saline tilapia is also propagated in fish cages in the ponds to produce green water which contributes in controlling the growth of luminous bacteria that is harmful to the shrimps.

Among the methods of combating aquaculture diseases, the use of green water technology was proven to be the most functional. Through this technique, pathogen growth can be inhibited, water quality can be improved and the immune system of the cultured species can be stimulated.

The use of biocontrol agents like living microorganisms, aside from being a biological method is said to be a very low-cost means to improve the shrimp farming industry in the country.

The green water technology is funded by the Bureau of Agricultural Research through its biotechnology R&D program.