Impact of diseases on aquaculture in the Asia-Pacific region as exemplified by epizootic ulcerative syndrome (EUS)

Traditional production systems rely on extensive management regimes that in volve low stocking densities and input levels. In recent years, however, th e aquaculture industry has evolved into a major force in the regional aquat ic economy. As a consequence, a major structural change has occurred, leadi ng to capital intensive production systems with high stocking densities and high operating costs. While this structural change has enabled many Asian countries to increase their aquaculture production multifold, it has not be en without environmental and socio-economic impacts; among the most importa nt are increasing fish health issues. Fish diseases are the major risk fact or in commercial aquaculture, with millions of dollars lost annually. There is a tendency for epizootic outbreaks to spread to other areas; lack of kn owledge on the aetiology and spread of these fish diseases requires much re search. A case in point is epizootic ulcerative syndrome (EUS). Despite reg ional collaborative research efforts from Australia to India over the last 6 years, scientists have still not been able to establish the primary facto r behind this disease. As this example shows, the lack of knowledge in fish health remains a major constraint in the development of the regional aquac ulture industry. This paper identifies long-term measures that producing co untries must implement to ensure the sustainability of the industry. These include quarantine systems to prevent the spread of exotic pathogens, toget her with diagnostic services. There is also an urgent need to improve husba ndry techniques to reduce fish stress, and to train operating personnel ade quately.