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Determination of the disease status of Western Australia commercial prawn stocks

Jones, J.B.ORCID: 0000-0002-0773-2007 (2003) Determination of the disease status of Western Australia commercial prawn stocks. Australian Government. Fisheries Research and Development Corporation

Abstract

There is little published information on the disease status of the prawns on the north-west shelf, yet these prawns ( Fenneropenaeus merguiensis, Metapenaeus endeavouri, Penaeus esculentus and Melicertus latisulcatus ) form the basis of a commercial fishery worth in excess of A$42 million in 2001-2002. There are also stocks of P. monodon on the shelf which form an important source of broodstock for the developing aquaculture industry in Western Australia, and potentially also for the Northern Territory and Queensland.

Unfortunately, prawns are infected with a variety of viral diseases, many of which have been translocated to new areas with movements of the host prawn – mainly for aquaculture but in some cases through frozen product destined for human consumption.

There is a zoogeographic barrier at the Torres Strait so there is no reason to expect that the prawns in Queensland and New South Wales will have the same diseases as those in Western Australia. This is particularly so since the northwest shelf has had little, if any, exposure to other areas through translocations. This presents a unique opportunity to study the viruses and other diseases that may have co-evolved in the area with the prawns. This isolation is already under threat, with, for example, the movement for aquaculture purposes of Gill Associated Virus (GAV) infected post-larvae from Queensland into the Northern Territory.

Thus, there are two disease risks for which this project provides background data. The first is the importation into Western Australia of prawns from other states and from the Northern Territory. To assess adequately the disease risk posed by the imports, we need to understand the local disease status and this has been achieved. The second risk is that diseases endemic in Western Australia may pose a risk to aquaculture establishments in other States. This report provides a basis on which those states can assess the risk to their own industries.

During the five years of the project over 2500 prawns have been examined for disease, mainly by histology, but also by molecular techniques for White Spot Syndrome, Yellow Head Virus, and Gill Associated Virus. Most of the prawns were sourced from the wild fishery, but both P. monodon and P. esculentus are now being spawned and on-grown in Western Australia under pilot scale or commercial conditions. The disease investigations associated with these nursery or grow-out operations have also been used in compiling this report. The two problems so far encountered in these prawns under aquaculture conditions are Monodon baculovirus-like virus (MBV-like virus) (in P. esculentus only) and bacterial problems (both species).

Overall, Western Australian prawns are exposed to MBV-like virus and Hepatopancreatic parvo-virus (HPV). Based on limited electron microscopy, an eosinophilic virus-like inclusion in epithelial cells particularly in the midgut, and similar to HPV but with different staining characteristics, may be a fixation artefact. There are a number of syndromes that may be associated with un-recognised viruses but could equally be due to autolysis and fixation artefacts. Further work is clearly required on these. There is also a rich fauna of metazoan parasites in most of the wild prawns. These are of little concern for aquaculture but probably deserve some taxonomic attention. The lack of MBV-like virus and HPV in P. monodon and the absence of GAV in any species are of particular note.

Item Type: Report
Series Name: FRDC Project No. 1998/212
Publisher: Australian Government. Fisheries Research and Development Corporation
Publishers Website: http://www.frdc.com.au/Archived-Reports/FRDC%20Pro...
URI: http://researchrepository.murdoch.edu.au/id/eprint/43200
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