Project number: 2017-190
Project Status:
Budget expenditure: $220,000.00
Principal Investigator: Stephen J. Wesche
Organisation: Department of Agriculture and Fisheries EcoScience Precinct
Project start/end date: 24 Feb 2018 - 30 May 2019


Achieving the mandated dose rate of 50 kGy for prawns harvested from the White Spot Disease control zone in SE QLD is proving to be problematic and industry are requesting a reduction in the permitted irradiation dose rate for prawns sourced from Moreton Bay to somewhere between 15 and 25 kGy. A reduction in treatment dose, if successful, would provide a viable option for industry to continue trade in uncooked prawns sourced from Moreton Bay.

There appears to be only three scientific papers relevant to the subject of using gamma irradiation for inactivation of WSSV (Heidareh et al. 2014, Kakoolaki et al. 2015, Motamedi-Sedeh et al. 2017). The studies were conducted with the aim of determining the doses required to inactivate the Iranian isolate of WSSV with gamma irradiation for the purposes of vaccinating cultured prawns. While the listed scientific papers suggest gamma irradiation at a dose of around 13-15 kGy is effective at inactivating WSSV, their experimental protocols and results are not clearly transferable. In these studies aliquots of free virus were exposed to different gamma irradiation doses. Irradiation of WSSV inside infected host tissues was not performed, and data on whether the surviving prawns were infected with WSSV were not presented. None of these papers are therefore directly applicable to the situation relating to irradiation treatment of WSSV in-situ inside infected prawns.

Given the absence of information on irradiation doses for inactivation of WSSV in the Department of Agriculture (2014) review document, and the absence of research in Australia or overseas to validate alternative irradiation doses that completely inactivate WSSV, new research is urgently required to determine the minimum safe irradiation dose for inactivation of WSSV in prawns with the results verified by controlled challenge trials in a bio-secure facility.


1. To determine minimal effective dose of gamma irradiation to render WSSV non-infectious in prawns.

Final report

ISBN: 978-0-7345-0470-8
Authors: Stephen Wesche Kerrod Beattie Nicholas Moody
Final Report • 2021-07-01 • 2.54 MB


White spot syndrome virus (WSSV) was detected in diseased farmed prawns by Biosecurity Queensland’s Biological  Sciences  Laboratory  and  confirmed  by  the  CSIRO  Australian  Centre  for  Diagnostic  Preparedness (ACDP) Fish Diseases Laboratory in November/December 2016. This exotic aquatic disease incursion resulted in the infection of all prawn farms, under production, along the Logan River, Queensland. Subsequent WSSV detections in prawns and crabs in northern Moreton Bay resulted in the issuing of a Movement Control Order and  subsequent  WSSV  biosecurity control order  under  the  Biosecurity  Act  2014,  which  prohibited  the movement of potential carriers (e.g. polychaete worms and decapod crustaceans) from Moreton Bay. These restrictions  included  wild  caught  prawns  from  Moreton  Bay  which  were  distributed  nationally  as  bait  for recreational  fishing.  Industry  established  protocols  to  treat  these  prawns,  for  distribution  as  bait,  using gamma  irradiation to  a  dose  of  50 kilogray (kGy).  However,  this  treatment  understandably  resulted  in increased costs of the final product, raising concerns that this would make imported commodity prawns a more likely source of bait for recreational fishing and consequently a biosecurity risk for introduction of exotic diseases.
The  primary  objective  of  this  project  was  to  determine whether gamma  irradiation treatment of WSSV infected prawns at a dose lower than 50 kGy would inactivate the virus as the bait wholesale industry indicated that a reduction in treatment dose to 25 kGy or lower would be required to provide meaningful cost benefits. Given  the  absence  of  information  on  irradiation  doses  for inactivation  of  WSSV, this collaborative project involving Department of Agriculture and Fisheries, Queensland, CSIRO ACDP, Steritech and industry, conducted research to evaluate the effect of reduced doses of gamma irradiation (10 kGy, 15 kGy, 20 kGy and 25 kGy) on inactivation of WSSV in infected prawns. 

Related research


Prawn White Spot Disease Response Plan

1. Deliver a Prawn Industry WSD Response Plan covering actions that can be implemented on individual farms by the whole of industry and government.
Seafood CRC Company Ltd