Strategic approaches to identifying pathogens of imported ornamental fish and the risk posed to biosecurity in Australia
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1
University of Sydney, School of Life and Environmental Sciences, Faculty of Veterinary Science, Australia
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2
James Cook University, College of Marine and Environmental Sciences, Australia
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3
University of Melbourne, VIC 3010 Australia, School of Mathematics and Statistics,, Australia
Introduction
In Australia, over 18 million ornamental fish are imported annually under a policy based on an import risk analysis (IRA) published in 1999. Research has shown that the existing pre-export biosecurity measures, health certification and post-arrival quarantining of fish in Australia were insufficient to prevent entry of fish with subclinical infections of exotic viruses (Becker et al., 2014, Rimmer et al., 2015). Of note was the detection of gourami iridovirus, a megalocytivirus closely related to Infectious spleen and kidney necrosis virus (ISKNV). As a result, since March 2016, Australia requires health certification for families of gourami, cichlid and poeciliid fish to be declared free of gourami iridovirus.
Also underway, Australia is trialing a random surveillance model for managing biosecurity risks associated with imported ornamental fish by shifting the emphasis of risk management off-shore. However, there is little information available on the assortment of disease agents carried by imported ornamental fish. The objective of this project was to determine if aquatic pathogens of potential biosecurity concern on the national list are entering Australia through the trade in ornamental fish.
Methods
Repeated cross sectional surveys were undertaken in imported freshwater and marine ornamental fish. Fish under quarantine prior to entry into Australia were tested for the presence of nationally listed aquatic viral and bacterial pathogens and to identify parasite assemblages. Freshwater fish were tested to the OIE standard to detect 2% prevalence with 95% confidence assuming a test of 100% sensitivity and specificity. Marine fish were tested for specific viral pathogens with a design prevalence of 10%.
Results and Discussion:
Fish hosts were prioritized based on prior knowledge of infection with the listed pathogens, volumes of importation to Australia and current import conditions. Testing of quarterly samples identified viruses of biosecurity concern, including ISKNV-like megalocytiviruses and viral nervous necrosis virus. The parasite assemblages found on pre-import ornamental fish were diverse and abundant. Many pre-import fish, in particular goldfish (Carassius auratus) from several countries were heavily infected with freshwater dactylogyrid gill trematodes. Other putative parasite species found on ornamental fish included ciliates, coccidians, myxozoans, nematodes, other trematodes, monogeneans, and crustaceans. Species confirmation is ongoing.
Determining the range of infectious agents carried by imported fish is required so that appropriate regulations can be put in place to manage the risk to Australian biosecurity. The current import conditions require all fish to be healthy and exhibit no clinical signs of significant infectious disease or pests at time of export to Australia. For goldfish only, there is an additional requirement for an effective parasite treatment within seven days before exportation. Live ornamental fish are recognised as posing a high risk for introducing aquatic animal pathogens and parasites (Whittington and Chong, 2007) associated with the release of imported ornamental fishes into the wild by ill-informed or misguided hobbyists (Freyhof and Korte, 2005). The results of this project will be used to inform national biosecurity policy and the current trial using a random surveillance model to manage the biosecurity risks of imported ornamental fish.
References
Becker, J.A., Tweedie, A., Rimmer, A., Landos, M., Lintermans, M., Whittington, R.J., 2014. Incursions of Cyprinid herpesvirus 2 in goldfish populations in Australia despite quarantine practices. Aquaculture 432, 53-59.
Freyhof, J.; Korte, E., 2005. The first record of Misgurnus anguillicaudatus in Germany. Journal of Fish Biology 66: 568-571.
Rimmer A.E., Becker J.A., Tweedie A., Lintermans M., Landos M., Stephens F.J., Whittington R.J., 2015. Prevalence and distribution of dwarf gourami iridovirus (Infectious spleen and kidney necrosis virus) in populations of ornamental fish prior to and after importation into Australia, with the first evidence of infection in domestically farmed Platy (Xiphophorus maculatus). Preventive Veterinary Medicine 122, 181-194.
Whittington, R., Chong, R., 2007. Global trade in ornamental fish from an Australian perspective: the case for revised import risk analysis and management strategies. Preventive Veterinary Medicine, 81, 92-116.
Acknowledgements
This study was funded by the Australian Government through the Fisheries Research and Development Corporation (FRDC) (Project No. 2014/001).
Keywords:
biosecurity,
ornamental fish,
ISKNV,
Virus Diseases,
Parasitic Diseases
Conference:
AquaEpi I - 2016, Oslo, Norway, 20 Sep - 22 Sep, 2016.
Presentation Type:
Oral
Topic:
Aquatic Animal Epidemiology
Citation:
Becker
JA,
Trujillo Gonzalez
A,
Hick
PM,
Robinson
A,
Tweedie
A,
Miller
TL and
Hutson
KS
(2016). Strategic approaches to identifying pathogens of imported ornamental fish and the risk posed to biosecurity in Australia.
Front. Vet. Sci.
Conference Abstract:
AquaEpi I - 2016.
doi: 10.3389/conf.FVETS.2016.02.00042
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Received:
27 Apr 2016;
Published Online:
14 Sep 2016.
*
Correspondence:
Dr. Joy A Becker, University of Sydney, School of Life and Environmental Sciences, Faculty of Veterinary Science, Camden, NSW, 2570, Australia, joy.becker@sydney.edu.au