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.

Diagnostic laboratories across the country vary in their diagnostic capability for aquatic animal pathogens. Due to their individual needs, many diagnostic laboratories have developed their own reagents and procedures for the identification of bacterial pathogens. This lack of standardisation can be problematical, for example, when reporting on aquatic animal health status. Using Vibrio identification as an example, it is likely that diagnostic laboratories would be capable of identification to the genus level (i.e. Vibrio sp.). However, due to differences in the various laboratories, identification to the species level would be difficult, and different laboratories are likely to use different procedures for identification.

There is a clear need for diagnostic scientists working in this area to compare and standardise protocols between States. A series of workshops aimed at providing training in the diagnosis of bacterial disease in aquatic animals for those new to the area, and at the same time providing an opportunity to evaluate the various diagnostic protocols used in Australia for their ability to identify both enzootic and exotic pathogens is overdue.

Development of Standard Diagnostic Techniques will require three logical steps:

1. Comparison and evaluation of the tests currently used by diagnostic laboratories;
2. Development of, and agreement on, the most sensitive, accurate and reproducible methods;
3. Adoption and publication of the agreed method for each pathogen as the Standard Diagnostic Technique.

Thus development of SDTs in aquatic animal bacteriology may include an SDT on general methods for aquatic animal bacteriology followed by SDTs for specific diseases such as Vibriosis. Vibriosis, due to its widespread occurence in vertebrate and invertebrate aquatic animal species in tropical and temperate regions of Australia, was identified as a disease of particular importance with respect to standardisation of diagnostic methods [1].

In order to ensure that the SDTs incorporate the latest technologies and information on exotic, as well as enzootic, bacterial pathogens, and that the SDTs will be recognised internationally as state-of-the-art, an international expert on the specific disease will be invited to participate in each of the respective workshops.

References

1. Fish Health Management Committee (1998). Report of the Fish Health Management Committee and the Fish Health Coordinating Group: Workshop on Aquatic Animal Health: Technical Issues, 7-9 December 1998, Melbourne, Victoria.