Prawn health management and disease control to sustain hatchery and pond production systems

• Research Institute for Freshwater Fisheres, Indonesia
• Central Research Institute for Fisheries, Indonesia
• Bureau of Fisheries and Aquatic Resources, Philippines
• Agency for Agricultural Research and Development, Indonesia
• James Cook University, Australia

Total world harvest of prawns in the Asia Pacific region was 2.1% in 1981. In 1989 it had risen to 26%. However, disease and pond environment problems are causing difficulties. During the early 1990s, total production dropped in China, Taiwan, the Philippines and Indonesia. Losses due to disease in Indonesia have been estimated at US$300 million, and in the Philippines only 65% of prawn hatcheries are operative.

Bacteria in the genus Vibrio have been implicated as a major cause of the problem. An outbreak of vibriosis can kill 70-90% of juvenile prawns, and significant production losses can result from low-level chronic mortalities and growth depression.

Most hatcheries rely on antibiotics to achieve acceptable survival levels. This encourages the emergence of resistant strains of bacteria, and therefore, is not sustainable. Also, aerosols containing antibiotic-resistant bacteria or antibiotics themselves pose health hazards to hatchery workers, and disposing medicated water presents environmental risks.

This project arose from discussions between ACIAR and CRIFI, with both seeing a need to develop collaborative research links in a number of aspects of prawn disease. Its main objectives are to:

develop practical, cost-effective, environmentally acceptable control and prevention methods for the bacterial diseases in prawn hatcheries; and

identify environmental and management factors which influence prawn growth and the occurrence of bacterial diseases in prawn ponds.

The research on disease prevention in hatcheries will include work on manipulation of the culture water and container, disinfection of larvae and food organisms, and the use of beneficial bacteria and immuno-stimulants. The second project objective will be addressed through studies of: the impact of various water quality parameters on the functional immunity of prawns; the value of 'vaccination' of prawns with bacterins; the importance of sulpha-bacteria and luminescent bacteria to the growth, survival and disease status of juvenile prawns; and potentially beneficial bacteria in pond water.