Training is needed, for fish farmers, technicians & veterinarians in all Australian States, for increased vigilance with respect to early disease detection, diagnosis, control and eradication of newly emerging endemic and exotic fish diseases. Northern States of Australia (NT, Qld) are at greatest risk for disease incursions, via the vast expanse of the States & Territories, remoteness of farms, illegal trade of fish, fish products, shipping movements (over 13 ports in Qld), people movement and the proximity of northern Australia to Indonesia, PNG and Asia. Early fish disease detection and eradication is necessary to protect the Biosecurity of the Australian Fish Farming industry, and prevent disease spread within and between States.

The continued annual growth of the barramundi & freshwater fish industries in all Australian States precipitates the need for farmer training for disease detection at the grass-roots level for farm workers to detect, control and treat fish disease, and thereby reducing disease risk to aquaculture enterprises and fisheries resources.

A specific training workshop is needed to train fish farmers, technicians, fisheries officers, vets, with hands-on, practical, technical skills & knowledge by Aquatic Animal health Professionals, so skills can be practically applied on farms during disease epizootics, investigations, and disease emergencies. This is needed to support continued growth, productivity, & sustainability of the Australian Fish farming Industry, disease being a limiting factor. This Workshop is needed to support on-going disease reporting activities by all States to DAFF, OIE and NACA, allowing continuation of Australian trade in fish and disease-free status.

Australian prawn production at around 22 kilotonnes is valued in excess of $250 million. Clearly, the prawn fishery is an important natural resource for Australia that is also the basis for a significant export industry. In addition, prawn aquaculture is a significant industry in northern Australia and accounts for around 14% of the total volume of Australian prawn production. Infectious myonecrosis is a viral disease that has caused significant disease outbreaks and mortalities in farmed Penaeus vannamei in Brazil and South-East Asia, including Indonesia. While P. vannamei is considered the principal host, experimental infection of P. stylirostris (Pacific blue shrimp) and P. monodon (black tiger shrimp) has been reported. The susceptibility of other shrimp/prawn species is unknown. Information on the susceptibility of prawn species important to Australia, including banana prawns (Fenneropenaeus merguiensis), brown tiger prawns (P. esculentus) is lacking. This project would provide information on the susceptibility of two important species of Australian prawns to exotic IMNV. Such information is important to policy-makers, regulators and primary producers with respect to relevant biosecurity issues at all levels of government.

1) TO REINFORCE THE TRANSLOCATION POLICY
Western Australia has approved a number of applications to farm prawns and there is increasing pressure to import postlarvae from Queensland. Also, prawn farms using local stock are being developed in areas adjacent to wild stock fisheries.

The disease risks are, therefore, two-fold: from introduced diseases and from endemic diseases which may be amplified through aquaculture hatchery and growout operations. Both situations can pose increased risks to wild stocks in adjacent waters and to the aquaculture ventures themselves.

There is almost no data available on the health status of existing prawn stocks within WA on which to base translocation decisions and disease management plans, other than the knowledge that virus diseases do occur. Whether aquaculture of prawns in WA is economically viable or not, the translocation of prawns from Queensland will result in the introduction of diseases with potential to affect both the disease status of the State and impact on the wild fishery. The prawn trawl industry was worth ca. $30 million in 1993-94.

However, the Fisheries Department of WA does not wish to hamper the development of farms by imposing unnecessary restrictions on translocation and further, under international and domestic guidelines, movements can only be prevented on disease grounds if surveys have actually confirmed a disease-free status. Absence of information is not a valid reason to prevent movements.

2) TO PROTECT THE DISEASE STATUS OF THE WILD STOCK FISHERY
Stocks of prawns off the north coast of Western Australia have not yet been exposed to introductions of prawns from other states or from overseas. They are, therefore, of great value commercially both for the production of specific pathogen free and for high-salinity stock. This potential market is being put at risk by the importation of prawn postlarvae for ongrowing with its potential to also import prawn viruses. Though steps are taken to minimise the risk of inadvertent spread of diseases to the local wild populations, overseas experience has shown that disease spread eventually occurs. We also know very little about the existing virus diseases and their impact on the wild fishery, and relationship to viruses elsewhere in Australia.

Disease, particularly Perkinsus disease, is seen as the fourth major risk to the sustainability of the abalone fishery in SA (SA Fisheries & Aquaculture Five Year Research and Development Strategy). Perkinsus disease causes ongoing losses to the industry, losses that are expected to increase with global warming unless some action is taken to curb the disease. This project will explore one approach that may be feasible to control Perkinsus and thus reduce its impact on the industry.

A recent project in California (Culver and Kuris, in press) successfully eradicated a species of mudworm from abalone by removal of the most susceptible shell (N. Bax, CSIRO, pers. com.)