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New aeration technology for shrimp aquaculture at NIO
Who would not like to have sustainable shrimp yields while maintaining the optimum water quality conditions and keeping surrounding environment clean. Systematic research, new tools and techniques, field experiments, have now improved the situation and the industry and the stakeholders have now better opportunities to make best use of all these environmental management strategies for sustainable production from small-scale aquaculture systems. Like many other developing countries, pond-based coastal aquaculture, particularly of shrimps, gained considerable momentum in India due to rapid returns from both national and international markets. Today, India occupies the fourth position amongst the major shrimp farming countries in the world. During the last decade, there has been a remarkable increase in annual shrimp production from 35,500 (1990-91) to about 113,000 tonnes with an export value of US $ 800 million.
Traditionally, the aerators are used to mix the air with water. The purpose is to increase the oxygen content of the water. Most of the aerators employed in aquaculture today, mix water with air either after the pump (e.g. Ejector base aeration) or with a propeller in open water (eg. Aire O2, Paddle-wheels etc). An innovative aeration technology developed in recent past by HOBAS water Engineering has many improved features. The project was taken up under the aegis of Indo-Norwegian Institutional co-operation programme by the National Institute of Oceanography (NIO), Goa from India and RF-Rogaland Research, Stavanger, Norwegian Institute for Water Research (NIVA) and HOBAS Tropical Aquaculture, Sola from Norway, to develop and demonstrate how the new technology could improve the water quality and in turn result in sustainable production under Indian conditions. The HOBAS aeration technology mechanically mixes air and water in order to replace oxygen deficits, and flushes the excreted, potential toxic, carbon dioxide and ammonia. The pump also creates horizontal physical water current in the pond when sufficient numbers of aerators are employed and implementation is done correctly.
A team of NIO scientists conducted various experiments for water quality, environment, bacteriology and production in commercial shrimp ponds along the Coastal Karnataka with the HOBAS aeration technology and noticed that it is capable of maintaining optimum water quality conditions, particularly the dissolved oxygen, healthy bacterial counts and maintain sustainable shrimp growth and resulting in lower Food Conversion Ratio (FCR). This technology, along with other Best Management Practices (BMPs), seeks to help improve conditions in the pond for better utilization of nutrients. Adoption of these technologies will result in increasing the yields by about 20-25% for two reasons: Due to the optimal environmental conditions in the pond during the production cycle and the increased phytoplankton production due to re-suspension of available nutrients. The HOBAS aerator also showed a strong ability and high capacity in flushing the possible toxic gases such as Ammonia and Hydrogen sulphide. This technology may be replaced or could be used in conjunction with the existing aeration technology for improvement in environmental conditions in the pond.
Few more trials of HOBAS technology, particularly along the east coast of India to generate data under different environmental conditions with the active involvement of stakeholders so that farmers gain confidence in this new technology is proposed. NIO would be providing R & D support to commercialize the HOBAS technology in India.
Scientists from NIO - Dr. D. Chandramohan, Mr. R.A. Sreepada, Drs. P.A. Lokabharathi, S.G. Dalal, X.N. Verlecar, B.S. Ingole and a group of young project assistants were involved in evaluating this technology and developing other Best Management Practices (BMPs) for sustainable aquaculture for last 3 years.
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