peer review of the biosecurity australia’s revised draft …€¦ · · 2014-08-08prawns and...

Peer Review of the Biosecurity Australia’s Revised Draft Generic Import Risk Analysis Report for

Prawns and Prawn Products

R S Morris, N Cogger, E J Peeler, L McIntyre

February 2007

Peer Review of Prawn IRA

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Table of Contents 1: Executive Summary .................................................................................................................. 1 2: Introduction ............................................................................................................................... 2 3: Methodology Used in the IRA ................................................................................................... 4

3.1 Risk assessment framework ............................................................................................... 5 3.1.1 Quantitative and qualitative analyses ........................................................................... 5 3.1.2 Scenarios evaluated ..................................................................................................... 6 3.1.3 Representation of mutually excusive scenarios ........................................................... 7 3.1.4 Compliance with OIE risk analysis structure ................................................................ 8

3.2 Consideration of all prawn and prawn products as equivalent to uncooked whole prawns 9 3.3 Consideration of volume and nature of trade .................................................................... 10

3.3.1 Annual volume and style of frozen prawns imported into Australia ............................ 11 3.4 Determining the partial likelihood of exposure .................................................................. 14

3.4.1 Exposure through feeding prawns in hatcheries ........................................................ 15 3.4.2 Exposure through use of prawns as bait .................................................................... 16

3.5 Infectious dose of various agents...................................................................................... 16 3.6 Combining the partial risk estimates to determine annual risk.......................................... 16 3.7 Use of single qualitative value without sensitivity analysis................................................ 17 3.8 Consequence assessment ................................................................................................ 17 3.9 Evaluation of risk management strategies ........................................................................ 17

4: Hazard Identification ............................................................................................................... 17 4.1 Coverage of hazards ......................................................................................................... 17 4.2 Taura syndrome virus........................................................................................................ 18 4.3 Infectious hypodermal and haematopoietic necrosis (IHHNV) ......................................... 18

5: Available Risk Management Strategies .................................................................................. 19 5.1 Cooking ............................................................................................................................. 19 5.2 Testing............................................................................................................................... 19

5.2.1 White Spot Syndrome Virus........................................................................................ 24 5.2.2 YellowHead Virus........................................................................................................ 24 5.2.3 Infectious hypodermal and haematopoietic necrosis virus ......................................... 24

5.3 Highly processed prawns .................................................................................................. 25 6: Product-Specific Assessment of Unrestricted Risk................................................................. 25 7: Unrestricted Risk Estimate for Uncooked Prawn Cutlets........................................................ 25

7.1 Introduction........................................................................................................................ 25 7.2 Method............................................................................................................................... 26 7.3 Unrestricted risk estimate for individual hazards............................................................... 26

7.3.1 White spot syndrome virus ......................................................................................... 26 7.3.2 Yellowhead virus......................................................................................................... 27 7.3.3 Infectious hypodermal and haematopoietic necrosis virus ......................................... 28

7.4 Sensitivity analysis ............................................................................................................ 29 7.5 Conclusion......................................................................................................................... 29

8: Unrestricted Risk Estimate for Uncooked Prawn Meat........................................................... 32 8.1 Introduction........................................................................................................................ 32 8.2 Method............................................................................................................................... 32 8.3 Unrestricted risk estimate for individual hazards............................................................... 32

8.3.1 White spot syndrome virus ......................................................................................... 32

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8.3.2 Yellowhead virus......................................................................................................... 33 8.3.3 Infectious hypodermal and haematopoietic necrosis virus ......................................... 34

8.4 Sensitivity analysis ............................................................................................................ 35 8.5 Conclusion......................................................................................................................... 35

9: Unrestricted Risk Estimate for Cooked Prawns...................................................................... 35 9.1 Introduction........................................................................................................................ 35

9.1.1 White spot syndrome virus ......................................................................................... 36 9.1.2 Yellow head virus........................................................................................................ 37 9.1.3 IHHNV ......................................................................................................................... 37 9.1.4 TSV ............................................................................................................................. 38 9.1.5 Tetrahedral baculovirus - baculovirus penai (BP)...................................................... 38

9.2 Conclusion......................................................................................................................... 38 10: Risk Management for Uncooked Whole Prawns .................................................................. 39

10.1 Sensitivity analysis .......................................................................................................... 39 10.2 Risk management options............................................................................................... 40

10.2.1 Removing the head................................................................................................... 40 10.2.2 Testing ...................................................................................................................... 42 10.2.3 Licensing importer..................................................................................................... 45 10.2.4 Defined market chain ................................................................................................ 45 10.2.5 Regulation of the bait industry and recreational fishing............................................ 48 10.2.6 Regulation of feeding practices on prawn farms and hatcheries.............................. 51 10.2.7 Commercial processing of imported uncooked whole prawns in AQIS approved facilities ................................................................................................................................ 54 10.2.8 Market limitations ...................................................................................................... 56

10.3 Combination of risk management options....................................................................... 59 10.3.1 Regulation of bait industry, recreational fishing and feeding practices on prawn farms and hatcheries ..................................................................................................................... 59 10.3.2 Regulation of bait industry, recreational fishing, feeding practices on prawn farms and hatcheries and commercial processing ........................................................................ 62

10.4 Sensitivity analysis for risk management options recommended in the IRA report ........ 65 10.4.1 Cooking..................................................................................................................... 65 10.4.2 Processing ................................................................................................................ 65 10.4.3 Head and shell removal ............................................................................................ 66 10.4.4 Testing and head and shell removal......................................................................... 66 10.4.5 Other risk management options................................................................................ 66

10.5 Sensitivity analysis-risk management strategies proposed in this report........................ 67 10.5.1 Combination option ................................................................................................... 67 10.5.2 Defined market chain ................................................................................................ 67

10.6 Recommendations .......................................................................................................... 67 10.7 Compliance with the Sanitary and Phytosanitary Agreement ......................................... 68

10.7.1 Proposed risk management methods ....................................................................... 68 10.7.2 Implementation of changes in current interim measures.......................................... 68

11: Conclusion ............................................................................................................................ 68 12: References............................................................................................................................ 68 Appendix 1. Summary of species susceptibility to the identified hazards ................................. 72

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List of Tables Table 1 Volumes and styles of prawns imported by survey respondents (tonnes) .................... 11 Table 2 ABARE Statistics for Prawn Imports (tonnes)................................................................ 12 Table 3 Estimated Total Imports of Frozen Prawn Products by Category and Style (tonnes) ... 12 Table 4: OIE approved PCR tests for White Spot Syndrome Virus (WSSV), Yellow Head Virus and Infectious hypodermal and haematopoietic necrosis virus (IHHNV). Text extracted from the OIE Manual of Aquatic Animals. ................................................................................................. 21 Table 5: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when uncooked prawn cutletsa are imported without restriction. .......................................................................... 31 Table 6: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk if imported prawns are tested using PCR molecular diagnostic tests. Results presented stratified by exposure group and pathogenic agent. ...................................................................................... 44 Table 7: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk if whole uncooked prawns were imported with a defined market chain. Results presented stratified by exposure group and pathogenic agent. ...................................................................................................... 47 Table 8: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when there is regulation of the bait industry and a ban on recreational fishing in the vicinity of prawn farms. Results stratified by exposure group and pathogenic agent....................................................... 50 Table 9: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk associated with importation of uncooked whole prawns when there is regulation of feeding practices in prawn farms and hatcheries. Results presented stratified by exposure group and pathogenic agent ........................................................................................................................................... 53 Table 10: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when commercial processing of imported uncooked whole prawns is undertaken in AQIS approved facilities. Results presented stratified by exposure group and pathogenic agent...................... 55 Table 11: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when there is market limitation on the sale of imported uncooked whole prawns. Results presented stratified by exposure group and pathogenic agent.................................................................... 58 Table 12: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when these is regulation of the bait industry, a ban on recreational fishing in the vicinity of prawn farms and regulation feeding practices on prawn and hatcheries. Results presented stratified by exposure group and pathogenic agent ....................................................................................... 61 Table 13: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk associated when there is regulation of the bait industry, ban on recreational fishing in the vicinity of prawn farms, regulation of feeding practices in prawn and hatcheries and limiting commercial processing of imported uncooked whole prawns to AQIS approved facilities. Results presented stratified by exposure group and pathogenic agent.................................................................... 64

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Glossary of Abbreviations ALOP – Appropriate level of protection under SPS Agreement BP – Baculovirus penai or Tetrahedral baculovirus IHHNV – Infectious hypodermal and haematopoietic necrosis virus IRA – Import Risk Analysis LE – Likelihood of exposure LEE – Likelihood of entry and exposure LR – Likelihood of release OIE – Office International des Epizooties, now known as World Organization for

Animal Health PALEE – Partial annual likelihood of release and exposure PAR – Partial annual risk of entry, exposure, establishment and spread PLE – Partial likelihood of exposure PLES – Partial likelihood of establishment and spread SIAA – Seafood Importers Association of Australasia Inc. SPS Agreement – Sanitary and Phytosanitary Agreement of the World Trade

Organization TSV – Taura syndrome virus WSSV or WSV – White spot syndrome virus WTO – World Trade Organization YHV – Yellowhead virus

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1: Executive Summary Biosecurity Australia released its Revised Draft Generic Import Risk Analysis Report for Prawns and Prawn Products in November 2006, updating an earlier draft commenced in 1997 and issued in 2000. Interim risk management measures were put in place following the issuing of that earlier report. The revised version of the IRA proposes changes to the risk management measures which have major implications for importing arrangements, even though the measures based on the first draft report were implemented in February 2001, and have been in place ever since. The revised draft has not been subject to external review. This report provides an independent scientific peer review of the IRA, and reassesses the appropriateness of the risk management strategy proposed in the draft IRA. It is concluded that the Executive Manager of Biosecurity Australia cannot meet the four requirements specified in the Import Risk Analysis Handbook (2003) for acceptance of the IRA, and therefore cannot recommend a policy determination based on the IRA in its present form. The IRA does not comply with the terms of the Sanitary and Phytosanitary Agreement of the World Trade Organization, or with the OIE Aquatic Animal Health Code. Deficiencies are identified and described which undermine the validity of the IRA as a basis for setting risk management measures which should be applied to imported prawns and prawn products. These deficiencies relate both to the use and interpretation of the scientific evidence and factual data, and to the analytical methods used. In addition to these analytical and data quality deficiencies, the IRA has a major structural deficiency which renders the conclusions invalid. It considers all prawn products to have an unrestricted risk equivalent to whole uncooked prawns, which is inconsistent with the scientific evidence. The IRA also fails to take any meaningful account of the annual volume of trade either in total, or (as should have been done) by product categories, grouped according to their risk level. When each category of product is separately assessed, it is found that the only product which requires risk management measures is uncooked whole prawns (including headless shell-on prawns). All other prawn products achieve Australia’s appropriate level of protection (ALOP) without the need for risk management measures. The IRA puts forward a risk management strategy for future application, but does not provide justification for its proposals within a transparent science-based risk analysis framework. This review concludes that the recommendations are excessive and unnecessary in relation to all prawn products other than whole raw prawns (including headless shell-on prawns). A range of potential risk management strategies are examined for this category of products. The initial part of the peer review documents serious flaws in the Biosecurity Australia risk analysis procedure, which should be corrected before any policy decisions are made on prawn imports. However pending that in-depth reassessment of the IRA procedure, analyses have been conducted using Biosecurity Australia’s own procedure and its estimated likelihood of events, except where values are explicitly modified to represent the reviewers’ judgment of the effect of specific risk management measures. When alternative risk management strategies are evaluated on that basis, two strategies are found to be effective. The first is the use of a defined market chain operated by

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licensed importers, in which the steps of the chain are subject to audited management of the risks, to prevent introduction of the five pathogens of concern. The second is a mix of pre-border and post-border risk management measures, which would involve industry and government in working together to protect Australia’s biosecurity status, and which in combination achieve Australia’s ALOP while allowing importation of whole uncooked prawns. Some of the post-border measures recommended here were promised as immediate actions by the Australian government in February 2001, but have still not been implemented. The draft IRA indicates that it is proposed to modify current interim risk management measures following closure of the period for submissions on the draft IRA. This intent has recently been reinforced by the Executive Manager of Biosecurity Australia in evidence to a Senate Committee. Such precipitate action can only be taken under the SPS Agreement if there are urgent circumstances which require such action. This report shows that no such circumstances exist, and that the deficiencies in the IRA are so severe that such action is completely unjustified. The modifications proposed to the present interim import standard for prawns and prawn products are clearly inconsistent with Annex B Clause 2 of the WTO SPS Agreement, and fail to comply with the provisions of Article 5 of the SPS Agreement because of major deficiencies in the IRA. There are no grounds for making immediate changes to the current interim risk management measures which have been in force since 5 February 2001, and any such changes should await completion of the entire IRA process. In addition, Animal Biosecurity Policy Memorandum 2001/06 stated that post-border measures would be implemented to complement the pre-border and border measures imposed on importers. Six years later, these post-border measures are not yet fully in place, demonstrating that there is no justification for urgently imposing additional onerous requirements on importers and trading partner countries in Asia, when commitments made by the Australian government to tighten post-border measures have still not been met. In summary, the draft IRA fails to provide a sound basis for protecting Australia’s biosecurity status, yet proposes the implementation of measures which are not validly based on scientific evidence and would clearly be in breach of Australia’s obligation under the WTO Agreement and the SPS Agreement not to apply sanitary measures in a manner which would constitute a disguised restriction on international trade.

2: Introduction Biosecurity Australia released its Revised Draft Generic Import Risk Analysis Report for Prawns and Prawn Products in November 2006, updating an earlier draft commenced in 1997 and issued in 2000. The revised version proposes changes to the risk management measures which have major implications for importing arrangements, even though the measures based on the first draft report were implemented in December 2000, and have been in place ever since. Despite the ten year period for which this import risk analysis (IRA) has been in preparation, it was not sent out for independent peer review prior to its release for public consultation although the Import Risk Analysis Handbook of Biosecurity Australia makes provision for this to be done as part of the process. The document is therefore

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entirely based on the opinions of members of the panel, and has not previously been subject to outside scrutiny by either scientists or risk analysts. The Seafood Importers Association of Australasia Inc. (SIAA) has therefore commissioned Professor Roger Morris and a team based at the Massey University EpiCentre in New Zealand to conduct an independent peer review of the draft report. The team was also requested to respond to the invitation from Biosecurity Australia in the draft report, to put forward risk management strategies which might represent practical alternatives to the measures recommended in the IRA, and which would also meet Australia’s appropriate level of protection (ALOP) under the Sanitary and Phytosanitary (SPS) Agreement of the World Trade Organization. The review team consists of the following people: Professor Roger Morris MVSc, PhD, FACVSc, FAmerCE, FRSNZ, CNZM. Professor Morris is Director of MorVet Limited, which has coordinated this review process, and Co-Director of the Massey University EpiCentre, a leading global centre for research, training and consultancy in epidemiology, risk analysis, veterinary public health, food safety, and animal health economics. Professor Morris completed his BVSc (Hons) from the University of Sydney in 1965, and was appointed to the academic staff of the University of Melbourne, where he combined large animal clinical practice with epidemiological research and investigation. During 11 years there, he completed a Master of Veterinary Science of the University of Melbourne and a PhD of the University of Reading, UK. He was promoted to Senior Lecturer, and was Director of the Veterinary Preventive Medicine Unit. He then moved to Canberra, where he was Assistant Chief Veterinary Officer in the (now) Department of Agriculture, Fisheries and Forestry, and Acting Chief Veterinary Officer on various occasions. He was Head of the Epidemiology Branch, which principally involved work on disease surveillance and policy development. He was then invited to become Professor of Veterinary Medicine and Chairman of the Department of Clinical and Population Sciences at the University of Minnesota, USA and was granted leave from the Department to take up this position, which he occupied 1981-86. In 1986 he resigned from DAFF and was appointed as Gilruth Professor of Animal Health at Massey University, New Zealand. Since then he has developed the EpiCentre, which currently has around 60 staff, contractors and postgraduate students. He is the author of about 200 scientific publications, and has been a member of the Editorial Board for various journals. He has also been a reviewer for many research organizations and a wide variety of journals (including Nature and Lancet). He has undertaken well over 100 consultancies for national governments, international organizations and other bodies, and has been a member or Chairman of a range of United Nations and OIE expert groups and committees. His areas of expertise are epidemiology, animal health economics, risk analysis, and human health implications of animal disease. He is a registered veterinary specialist in both veterinary epidemiology and pig medicine. He advised the Australian National Audit Office in its review of import risk analysis procedures, and the New Zealand Auditor General in his assessment of biosecurity arrangements. Dr Naomi Cogger was awarded a BSc (Hons) from the University of Sydney in 1999. She then completed a PhD at the University of Sydney in which she investigated the epidemiology of injuries in thoroughbred racehorses. In 2003 Naomi was employed as a research officer at the EpiCentre, Massey University. Since then she has taught

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import risk analysis, epidemiology, and applied statistics to post graduate students. Her research and consulting activities have focused on application of risk analysis methods to biosecurity. Currently she is working in conjunction with co-workers to develop a risk-based surveillance system for Trichinella in the United Kingdom. Previously, Naomi completed an import risk analysis (IRA) for the importation of frozen porcine embryos into Australia using both qualitative and quantitative methods, and supervised an IRA to develop a cost-effective approach to managing the risk of Trichinella infection in consumers in countries importing New Zealand pork products. In 2006, she was a member of a team which undertook a peer review of the methodology used to quantitatively assess the BSE risk to British consumers. She has also participated in peer reviews of other risk analyses. Dr Ed Peeler qualified as a veterinarian from the University of Cambridge in 1989 (MA VetMB, MRCVS). After qualifying he spent two years in large animal practice in the UK. In 1991 he joined the associate professional officer scheme run by the Overseas Development Agency (ODA) and completed a masters degree in veterinary epidemiology in 1992. Ed was employed by the ODA to work on a UK funded epidemiology and economics research project in Kenya (1993-1997). On his return to the UK, he studied the epidemiology of clinical mastitis for which he was awarded a PhD by the University of Bristol (2001). He was employed in 2001 by the Centre for Environment, Fisheries and Aquaculture Science (a UK government science agency) to establish epidemiology within the fish disease laboratory and provide advice to government. Much of his work focused on applying import risk analysis to support the development of fish health policy. In February 2006 he joined the EpiCentre, Massey University as a Senior Lecturer. During his time at Massey he has contributed to an import risk analysis for pig embryos to Australia and a project scoping prawn and other food safety issues in Indonesia. He is a diplomate of the European College of Veterinary Public Health. Lachlan McIntyre obtained a degree in Agricultural Science and then completed a veterinary degree at Massey University in 1989. He spent ten years in veterinary practice, specialising particularly in herd and flock medicine. He then undertook a Masters degree in epidemiology, and specialised in epidemiological consulting. He operates GlobalVet Ltd, and provides consulting services to organizations, principally through Massey University EpiCentre. He has undertaken a major project in aquatic epidemiology, and a diverse range of other epidemiological consultancies, both in New Zealand and overseas. These include representing the New Zealand government on seven live sheep shipments to the Kingdom of Saudi Arabia. He has particular research interests in disease surveillance and electronic systems for capturing animal health data.

3: Methodology Used in the IRA This section of the review considers the extent to which the IRA complies with required procedures. As stated in the DAFF Import Risk Analysis Handbook:

In considering the recommendations in the Final IRA Report, the Executive Manager of Biosecurity Australia must be satisfied that the IRA has been

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conducted in accordance with the process described in the handbook, and the recommendations: • Are reasonable in the light of the evidence • Meet the Government’s objectives for biosecurity • Are consistent with Australian legislation • Accord with Australia’s international rights and obligations.

With regard to the fourth of these points, this requires that the IRA comply with World Trade Organization requirements, particularly the Sanitary and Phytosanitary (SPS) Agreement, and derivative requirements specified by the World Organisation for Animal Health (OIE), notably in this case the OIE Aquatic Animal Health Code. This peer review has found that the draft IRA does not meet these requirements in a number of important respects, which will now be described. As a result, it is concluded that the Executive Manager of Biosecurity Australia would not comply with the Handbook procedure if he accepted the recommendations in the IRA, since it fails to meet the requirements listed above.

3.1 Risk assessment framework

3.1.1 Quantitative and qualitative analyses An IRA may be fully quantitative, semi-quantitative, or purely qualitative. This IRA represents a significant shift in approach by Biosecurity Australia from other recent IRAs, in that it is entirely qualitative, but uses various sets of decision rules in order to categorise and then combine risk estimates. These decision rules are different from those used previously.

The acceptability of this approach depends on the qualitative evaluation being transparent (as required by the SPS Agreement) and analytically valid. To achieve transparency, the analysis must make clear what steps were followed to reach particular conclusions. The IRA uses scenario trees to specify the nature of the phases of the analysis, such as release assessment, exposure assessment, etc. However, on detailed examination of the way in which likelihood values were assigned to the various components of the analysis, the processes within each phase were not separated into a sequence of scientifically appropriate steps as required for a scenario tree approach, but rather were treated as single values, which were subjectively assigned by the IRA team. The reasoning which led to the team assigning a value of ‘moderate’ rather than ‘low’ is not provided, and hence the analyses are not transparent. In addition, no effort is made to test the robustness of conclusions to variation in crucial qualitative values, by means of sensitivity analysis. Hence not only is the estimate lacking in transparency and not adequately open to scientific scrutiny, but it is also lacking in analytical rigour, because values attributed to particularly parts of the analysis by the IRA team are treated as perfect, with no consideration of the effect of any errors of judgment. Even errors in transcription or recording may become embedded in the analysis and will not be necessarily detected, because no double-checking can reliably be done when decisions on values are purely subjective.

As one example of the problems with the way the IRA has been reported, cooking was found to be an effective risk management option for IHHNV, as it was stated to reduce the annual risk below ALOP. We agree that this is the correct conclusion. However inspection of reported results on page 177 showed that cooking was only expected to

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reduce the partial likelihood of entry and exposure associated with IHHNV to very low, whereas for white spot and YHV cooking reduced it to extremely low. The IRA does not provide all of the other values used for the restricted risk estimate, but from the values we have worked out that Biosecurity Australia was using in these restricted risk estimates to get the results they have reported, the annual risk for IHHNV following cooking would only be evaluated as low, and therefore above Australia’s ALOP. While, it would appear that this was an oversight (we assume they meant to write extremely low), this highlights the serious lack of transparency in the IRA, and leaves the informed reader with serious doubts about the accuracy of results which cannot be checked (due to failure to report the results in sufficient detail that the analyses can be reproduced). An essential feature of scientific evaluation is that it must be possible to reproduce the method, and this IRA fails on this crucial feature. It is therefore impossible to know whether there are any cases (other than the above one) where a setting does not match the actual decision of the IRA Panel, and hence the results reported in the IRA are incorrect.

3.1.2 Scenarios evaluated The problems with the analytical approach are substantially compounded by the fact that the only two scenarios evaluated as possible outcomes of an incursion were either:

Scenario 1 – the agent establishes and spreads to wild and farmed populations of susceptible species in Australia, to its natural limits

Scenario 2 – the agent does not establish Scenario 2 is effectively not an incursion, since establishment fails and therefore it has no long-term consequences. Since it is stated that the release is not even detected before infection is spontaneously eradicated, there are not even any short term trade consequences, and the incursion is a ‘non-event’ in every respect. Hence results reported for Scenario 2 have no realistic meaning in relation to the assessment of disease risk associated with importation of prawns. It is therefore totally inappropriate to use this as one of only two scenarios.

Therefore only one realistic scenario is considered, in which all agents are equally considered to spread to their natural limits, without effective control and with maximum adverse consequences. In other Australian IRAs, successful detection and control is assumed to occur in accordance with AusVetPlan response strategies, thus limiting the impact of an incursion. Yet in this IRA, no consideration is given to the possibility that an incursion into one of the 24 prawn farms in the country would be detected and eradicated before it can spread to other farms or to the wild prawn population.

This is inconsistent with Australia’s official control plan for exotic prawn disease, AQUAVETPLAN.

AQUAVETPLAN deals with white spot syndrome virus, considered the most serious of the agents, and states the following:

Based on overseas experience, an outbreak of WSD in Australia is most likely to occur and be detected in farmed penaeid prawns, although the possibility of occurrence in other farmed crustaceans cannot be ruled out. It is unlikely that an outbreak of WSD will occur in wild crustacean populations, but WSV infection could be detected. This section provides background information to enable the choice of the most appropriate control measures following either the occurrence of a WSD outbreak or detection of subclinical WSV. It focuses on the prawn farming industry, since most available information is derived from this sector, although the principles can be applied to other crustacean

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aquaculture enterprises or wild populations. In the following discussion, the term WSD will be used to refer to both an outbreak of the disease and to confirmed WSV infection. The basic principles of eradication and other control responses are described in the AQUAVETPLAN Enterprise Manual and Control Centres Management manual. See the Enterprise Manual for state and territory legislation relating to disease control and eradication. There are essentially three broad control options for WSD in Australia: • Eradication — eradication of WSV from Australia (highest level of control measure and likely to be highest cost). • Containment, control and zoning — containment of the virus to areas with endemic infection, prevention of further spread and protection of uninfected areas. • Control and mitigation of disease — implementation of management practices that decrease the incidence and severity of clinical outbreaks (lowest level of control measure and likely to be lowest cost). Within these overall options, the general principles for the control and eradication of WSV include: • rapid detection and identification of infection; • rapid definition of the nature and extent of the problem; • rapid definition and implementation of control measures; • prevention of viral spread, by controlling stock and water movement within and between farms or other infected sites; and • maintenance of good management practices and high hygienic standards.

Thus it is clear that a range of incursion scenarios has already been considered, and could have been evaluated in the IRA. The one chosen is inconsistent with the expected nature of an outbreak, as described in AQUAVETPLAN.

This choice of only unrealistically extreme scenarios, one of which results in spontaneous eradication, seriously biases the evaluation process, since effectively all incursions are considered to produce endemic infection in both farmed and wild prawns throughout the entire geographical range of wild and farmed prawns.

The evaluation should have considered 4 to 5 incursion scenarios across a range from localised establishment in a single prawn farm and subsequent eradication, through intermediate outcomes to the outcome described as Scenario 1. Given that the analysis was qualitative, this would not have involved a significant increase in analytical load, but would have provided a realistic spectrum of outcomes.

3.1.3 Representation of mutually excusive scenarios The two outbreak scenarios considered in this analysis could not occur simultaneously – so they are mutually exclusive events. In a quantitative risk assessment, this would mean that the probability of outbreak scenario 1 is one minus the probability of outbreak scenario 2, and vice versa. Thus for the case where only two outcomes are possible, if you know the probability of one event you can deduce the probability of the second event occurring. Although the IRA used a qualitative framework, these basic probability rules cannot be ignored, as they appear to have been in the evaluation. The decision rules for assessing consequences in Table 3.4 and the following un-numbered Table (pp. 36-37) are very heavily influenced by the number and nature of the scenarios chosen for evaluation, and cannot be considered an unbiased method of deciding the weighting to be given to the consequences of an incursion.

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3.1.4 Compliance with OIE risk analysis structure The IRA for prawn and prawn products divides the steps of the analysis up in a way which does not comply with the OIE Aquatic Animal Health Code, and the deviations have implications for the validity of the analysis.

The release assessment correctly considers the likelihood that an identified hazard would enter an importing country in the product to be imported. However, the exposure assessment determines only the likelihood that a susceptible animal in the importing country would be exposed to an identified hazard. The likelihood of establishment, spread and the biological and economic consequences of introduction are jointly considered in the consequence assessment. Finally, the unrestricted risk estimate for each of the identified hazards is determined by combining the likelihoods and consequence in a risk estimation step.

The scope of the exposure assessment does not comply with the OIE Aquatic Animal Health Code, because it excludes the likelihood of spread or establishment of the hazard. The Code states that the exposure assessment must consist of an evaluation of:

the biological pathway(s) necessary for exposure of humans and aquatic and terrestrial animals in the importing country to the hazards and estimating the likelihood of these exposure(s) occurring, and of the spread or establishment of the hazard.

Instead, the IRA considers the likelihood of spread or establishment in the consequence assessment. It has been suggested by Biosecurity Australia personnel that this deviation from the required procedure is because Australian IRAs all follow the procedure in the Terrestrial Code. However a comparison of the two codes shows that in both cases the likelihood of establishment and spread belongs in exposure assessment, but the Aquatic Code is simply more explicit in the wording used to express this requirement.

The effect of not considering the likelihood of spread or establishment in the exposure assessment is that the partial likelihoods of exposure for each of the at-risk groups are substantially overestimated, since mere presence of the agent in Australia is called exposure, even if no prawns are ever in fact infected or infection fails to establish and become self-maintaining.

By combining the likelihood of spread and establishment with the consequences of an incursion, and then limiting the incursion scenarios to two quite extreme cases at opposite ends of the scale of spread, the structure of the analysis is distorted and fails to adequately represent the true expected consequences. The evaluation process is biased by this non-compliance with the OIE Code. This is likely to have inflated the unrestricted risk estimates for individual hazards.

Therefore, it is possible that the unrestricted risk for some hazards exceeds ALOP purely because the framework used to assess the risk was biased and incorrectly constructed.

The IRA does not therefore meet a basic and analytically important requirement which it must satisfy in order for the Executive Manager of Biosecurity Australia to approve it.

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3.2 Consideration of all prawn and prawn products as equivalent to uncooked whole prawns

The title of the report suggests that the IRA was conducted for prawn and prawn products, but the evaluation of the disease risk was conducted only for non-viable, farm-sourced, frozen, uncooked, whole prawns intended for human consumption, and no separate evaluation was conducted for the various lower risk products to determine whether these products met ALOP without risk management measures.

Thus, the unrestricted risk estimate made for uncooked, whole prawns (including headless shell-on prawns) has also been applied to all imported prawn and prawn products including prawn cutlets1, prawn meat2, cooked prawns and highly processed prawn products (collectively referred to in this review as ‘processed products’). The scientific evidence shows that the disease risk associated with each of the products which have undergone some degree of processing will differ from whole uncooked prawns in the risk they pose, and must be considered separately in the analysis.

The likelihood of release for these products will be less than uncooked prawns because a considerable proportion of the high-risk material has been removed and/or the pathogen deactivated by the cooking process.

The partial likelihood of exposure for these processed products will also be less than for whole uncooked prawns for several reasons. Firstly, prawn cutlets, prawn meat, cooked prawns and highly processed prawn products are extremely unlikely to undergo commercial processing for human consumption within Australia, but will be processed in the source country. Therefore, the volume of untreated waste produced in Australia (and hence hypothetically available to expose domestic prawns) would be much less for these products than for whole uncooked prawns, thereby reducing the likelihood that farmed, hatchery and wild crustaceans will be exposed to an identified hazard. Secondly, the proportion of product entering retail outlets is different for each of the products, as described in 3.3.1.

According to the IRA, retail outlets supply prawns for use as feed to condition broodstock in hatcheries and for use as bait or berley by recreational fishers. Therefore, reducing the volume of product entering the retail outlet should reduce the likelihood of exposure in the hatchery and wild groups. Thirdly, as discussed below, feeding of prawns to broodstock in prawn hatcheries is not considered an acceptable or useful practice, and even if it did occur any individuals who might conceivably engage in this practice would not use any form of processed prawns since any perceived benefit is associated with the shell.

Therefore, the partial likelihood of exposure for the hatchery group will be less for raw cutlet, raw meat and cooked products than for whole, uncooked prawns. Finally, likelihood of crustaceans being exposed to disease as a result of recreational fishermen will be reduced because raw cutlets, raw meat and cooked prawns are less suitable and far less likely to be used as bait or berley than whole prawns.

Because the IRA fails to adequately distinguish between different types of products, with different risk levels, it cannot adequately weight quantities of various products by their risks to produce product-specific annual risk estimates. The discussion of risks in the report fails to make clear that the quantities of different products are markedly different, and that the annual risk as stated fails to take any account of this. 1 Prawn with head and shell removed, leaving the last tail segment in place. 2 Prawn with entire head and shell removed

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For these reasons it is considered that separate unrestricted risk estimates should have been conducted for:

Non-viable, farm-sourced, frozen, uncooked, whole prawns intended for human consumption;

Non-viable, farm-sourced frozen, uncooked prawns with head and shell (excluding the last tail segment) removed (i.e. prawn cutlet);

Non-viable, farm-source, frozen, uncooked prawns with head and shell (including the last tail segment) removed (i.e. prawn meat); and

Non-viable, farm-source, cooked prawns and prawn products.

It is shown later in this report that by failing to distinguish different risk categories of products, invalid conclusions have been drawn in the IRA.

3.3 Consideration of volume and nature of trade The IRA states that it:

looked at the likelihood of entry and exposure of a pathogenic agent over a period of a year. As such, the release and exposure assessments for each agent were based on expected annual volume of trade in the commodity.

Consideration of the annual volume of trade by product type (grouped in different risk categories) is essential when investigating the annual likelihood of entry and exposure. However, the report does not provide any explanation of how the volume of trade was incorporated into the risk estimates. Nor are there details of what value was used for the expected annual volume of trade under the substantially changed policies proposed in the recommended future risk management strategy. The only information about the volume of trade was derived from ABARE commodity statistics for all prawn and prawn products combined, and the data did not distinguish between whole uncooked prawns, prawn cutlets, prawn meat, cooked prawns and highly processed prawn products.

In discussion with Biosecurity Australia staff, it was apparent that the total volume of trade had not been considered in any realistic way, and that no account whatever had been taken of the fact that the total volume of trade was made up of multiple different product categories with different inherent risk levels. This should have been taken into account in the release assessment. In addition, products which go into different distribution systems (retail or food-service) and different end-uses (home-cooked, processed prior to wholesale distribution, etc) have very different exposure risks and none of these factors were included in the exposure and consequence assessments, as they should have been.

On this basis alone, the unrestricted risk estimates are totally misleading and unsuitable as the starting point for consideration of risk management strategies.

The IRA provides very little information on the nature and scale of imports, and what it provides is entirely based on very crude statistics provided by the Australian Bureau of Agricultural and Resource Economics (ABARE). Given the issues raised above, the ABARE statistics alone are quite inappropriate to use in determining the likelihood of entry and exposure for either whole uncooked prawns or for processed products.

More detailed information is readily available from importers, and could have been provided voluntarily on request. In order to illustrate that such data is readily available

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and provides far better insights into the true risk of introduction of prawn diseases into Australia, a very rapid survey was conducted of major importers by Phillip Walsh of Food Factotum. It is summarized below, because it provides very valuable guidance on quantities of different products imported. The majority of importers (representing 60% of imports) responded within the very tight return time available (three days), and with additional response time coverage could be raised significantly further.

3.3.1 Annual volume and style of frozen prawns imported into Australia SIAA commissioned Food Factotum on 8th February to carry out a brief survey of members to identify tonnages of the various styles of prawns imported over the previous 12 months and report back by 13th February. Food Factotum carried out a similar survey for SIAA in October 2000 in response to the earlier Draft Import Risk Analysis Paper, prawn and prawn products (2000/41). A comparison of the two surveys is included in the discussion. In 1999 Food Factotum prepared a report for the Australian Quarantine and Inspection Service on Imports of Non-Viable Marine Finfish Products. The Draft IRA clearly identifies the farming of L vannamei in Asia as the reason for the decrease in the retail price of prawns and the increase in volume of prawn imports since the 2000 Draft IRA was published. Therefore, in this survey, importers were asked to identify L vannamei separated from ‘all other species’ of prawns and to identify for all frozen prawn imports the tonnage (last available full year’s figures) of each style of prawn imported. To ensure confidentiality, all results were aggregated and only the total tonnage for each style of prawn reported. Table 1 summarises results for L vannamei prawns versus all other types on an annual basis. Table 1 Volumes and styles of prawns imported by survey respondents (tonnes) L.vannamei All Other Species Total Raw (Green) Prawns Whole 71 624 695Headless 18 1 19Cutlets* 356 3140 3496Prawn Meat 763 927 1690Breaded/Battered 165 1037 1202Other (eg marinated)# 213 60 273Total Raw 1585 5790 7375 Cooked Prawns

Whole 5147 341 5488Headless 0 0 0Cutlets* 1023 44 1067Prawn Meat 308 1013 1321Other# 7 0 7Total Cooked 6485 1398 7883 Total All styles 8071 7187 15258

* Cutlets are prawns with head removed and shell peeled to the last segment, tail shell remains. # Includes prawns marinated in sauces, garlic butter prawns, marinated on skewers, breaded on skewers etc. The total annual tonnages can be obtained from ABARE’s Australian Fisheries Statistics 2005 and shown in Table 2.

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Table 2 ABARE Statistics for Prawn Imports (tonnes) Year Fresh, Chilled, Frozen Canned and Preserved

2002/3 13,086 5,032 2003/4 18,860 5,584 2004/5 22,590 7,247

Relatively few prawns are imported fresh chilled, but the canned and preserved statistic also includes a proportion of the ‘cooked & peeled’ frozen prawn imports. Therefore, 25,000 tonnes is taken as the current best estimate of frozen prawn imports. Assuming 25,000 tonnes of frozen prawn imports per annum and applying the same ratios as in the survey, annual tonnages by style of prawns can be estimated as shown in Table 3. Table 3 Estimated Total Imports of Frozen Prawn Products by Category and Style (tonnes) L vannamei All Other Species Total Raw (Green) Prawns Whole 117 1030 1147Headless 29 2 31Cutlets* 587 5182 5768Prawn Meat 1259 1530 2788Breaded/Battered 272 1711 1983Other (eg marinated)# 352 99 451Total Raw 2615 9553 12168 Cooked Prawns Whole 8493 563 9056Headless 0 0 0Cutlets* 1688 72 1760Prawn Meat 508 1672 2180Other# 12 0 12Total Cooked 10701 2306 13007 Total All styles 13316 11859 25176

* Cutlets are prawns with head removed and shell peeled to the last segment, tail shell remains. # Includes prawns marinated in sauces, garlic butter prawns, marinated on skewers, breaded on skewers etc. Although the survey captured over 60% of all frozen prawn imports, the extrapolation from the survey to total annual tonnage must be treated with considerable caution, and more complete data collection would reduce the uncertainty. However, a number of comments can be made with some confidence:

• L vannamei prawns dominate the cooked prawn component comprising over 80% of total cooked and over 90% of whole cooked frozen prawn imports.

• By contrast, very few whole raw L vannamei are imported. This is consistent with the current ban on whole raw prawn imports less than 15g and the extra cost of growing large vannamei prawns. Importers also comment that the darker colour of raw whole vannamei prawns makes them less appealing for retail sale.

• Total imports of whole raw prawns remain at relatively low levels, comprising 4.5% of total imports. In a similar 2000 survey, 6.4% of all prawn imports were whole raw prawns.

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• There is an approximate 50:50 split between raw and cooked prawn imports, unchanged from the 2000 survey. However, the ratio of whole cooked to meat (cooked and peeled) is now 80:20, whereas in 2000 the ratio was 60:40

• The survey confirms the Biosecurity Australia comment that L vannamei now dominates total imports by species, but 80% are cooked, and only 1.1% are whole raw or headless prawns. For other species of prawns, 8.7% were whole raw or headless, but imported raw prawns make only a modest contribution to total raw prawn consumption. The IRA report does not provide information on the proportion of domestic prawn production which is sold raw, but the bulk of prawns supplied in this form are of Australian origin.

The survey of importers in 2000 identified 70% of all prawn imports (10,000 tonnes out of 14,000 tonnes total) of which there was roughly a 50:50 split between uncooked and cooked prawns. Raw whole prawns comprised 6.4% of the total imports, of which 65% were farmed (4.2% of total imports). This short 2007 survey gathered data on 60% of the estimated 25,000 tonnes of imported frozen prawns and prawn products currently entering Australia per year. It confirms the 50:50 split between raw and cooked prawn imports is still valid, confirms that whole raw imports remain at low levels (<5% of the total) and confirms that large volumes of L vannamei are now being imported, most of which are pre-cooked. The increase from 14,000 to 25,000 tonnes over the seven year period is concentrated in the ‘value added’ raw prawn products (cutlets, breaded, marinated) and cooked whole prawn categories, with a very low proportion imported as whole raw prawns or headless prawns. A problem highlighted in the 2000 survey was the lack of specificity in the customs tariff codes. At that time, code 306130003 covered frozen raw whole prawns, frozen raw peeled prawns and frozen cooked whole prawns. Changes were subsequently made to the codes by separating cooked from raw and separating farmed from ‘not farmed’, but the separation of whole from peeled recommended in the report was not carried out. Neither was the recommendation to specify a code for all cooked product implemented. Thus frozen whole prawns are captured by tariff code 0306130040 together with some peeled prawns, whilst the remaining cooked and peeled prawns are captured under a ‘prepared or preserved code’ 1605200019. This latter code appears in ABARE’s Australian Fisheries Statistics 2005 as ‘Canned and preserved prawns’. Food Factotum in their report to AQIS from the 1999 survey of finfish imports noted a number of errors in the recording of customs tariff codes and a general lack of specificity in the harmonised tariff code system. Whilst applying international codes is essential for international trade there is room for sub-categories to ensure that the categories of produce of particular concern for biosecurity or food safety are readily identified. For imported prawn biosecurity it is important to be able to identify whole raw (green) prawns separately from the various ‘value added’ forms such as cutlets, meat and breaded prawns. However tariff code 0306130041 covers both frozen farmed whole and frozen farmed peeled prawns. Moreover, tariff code 0306130042 is intended to identify ‘not farmed’ prawns separately from ‘farmed’ product yet the statistics provided by ABARE to SIAA and forwarded to Food Factotum appear to show over 5,000 tonnes per annum imports of ‘non farmed’ product. This is clearly not the case and no reliance has been placed on the individual tariff codes in this report. It is recommended that a further review of tariff codes be undertaken with a view to ensuring the codes capture the statistics of relevance, followed by an education campaign to ensure that the correct codes are applied when import documents are lodged.

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These findings demonstrate that only a small proportion of imports are in whole raw form, and that any evaluation of risk must take account of the annual quantity of prawns imported in each style, grouped into products which have similar risk levels. Thus there is no validity to the claim that the risk has increased substantially because imports have risen, since little of the increase has been in products which would represent a risk. Since it is shown below that the risk is quite different for various product groups, both the risk level and the scale of importation must be taken into account for a valid risk analysis. As discussed above, neither of these elements of a valid analysis has been dealt with correctly or accurately in the draft IRA.

3.4 Determining the partial likelihood of exposure According to the report, the IRA considered volumes of potentially infected or contaminated prawns, and associated wastes, likely to be directed toward each exposure group when determining the partial likelihood of exposure in each group. We agree this is a very important consideration, and the structure of the procedure followed in the IRA (discussed earlier) means that this partial likelihood has a very strong influence on the results of each evaluation.

However, there is no explanation of how the relative contribution from each exposure pathway was assessed and incorporated, nor the data sources that were used. Some of the information that should have been provided includes:

• Number of hatcheries in Australia (actually 14);

• Number of prawn farms (actually 24);

• Proportion/Volume of imported product that is commercially processed within Australia;

• Proportion/Volume of imported product that is sold through retailers.

• Proportion/Number of hatcheries that are known or believed to feed fresh/frozen prawns to broodstock; and

• Volume of imported prawns that would be fed to broodstock.

• Current data on the scale of use of imported prawns as bait and berley by fishers3, which is available in the updated Kewagama report, but which was not used in the IRA and has been withheld from us by Biosecurity Australia in the preparation of this report.

We do not believe it would be possible to determine the relative volume of product directed towards each risk pathway without this information.

The issue of the scale of risk attached to each pathway will now be evaluated. There are some very fundamental differences between terrestrial animals and prawns in relation to the operation of transmission pathways and the realistic likelihood that if a disease agent was present in Australia it would result in infection of domestic stock.

3 The IRA quotes from an unpublished report by ADVS (1999) on the use of prawns as bait; but the relative importance of imported and domestic prawns in bait use is not considered. In this study most of the ‘human consumption’ prawns used as bait were wild caught by the consumers, and are not representative of the pattern of use in the wider community.

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Terrestrial species of commercial significance are located on very large numbers of properties, with varied skill levels and attitudes between owners. Some species (such as pigs) are likely to seek out food items which could be of higher risk than other food items, and may initiate an infection which is then passed on to other species. Transmission networks involve movement of animals and fomites, sometimes over long distances, in complex social networks. In contrast, there are only 24 prawn farms in Australia, which are highly specialised and aware of the risks to their businesses, including biosecurity risks.

Their biosecurity risks are not limited to imported prawns, but may arise from a number of sources. Global experience is that transmission of prawn diseases occurs almost entirely through movement of breeding stock, rather than diversion of dead prawns intended for human consumption (Flegel and Fegan 2002; Flegel 2006).

Of the exposure mechanisms considered in the IRA, only two are of sufficient importance to influence the results significantly, and they will now be evaluated. The third mechanism considered, infection from processing waste, is extremely unlikely because almost all processing is undertaken in the country of origin, and very little risky waste is produced by processing plants in Australia.

3.4.1 Exposure through feeding prawns in hatcheries The IRA treats this as an important risk, and no risk management strategy can be effective within the Biosecurity Australia risk analysis structure unless it substantially reduces the importance of this pathway. However the analysis provides no evidence to support the claim that raw prawns are currently fed to hatchery breeding stock. Discussions undertaken during the preparation of this report cast serious doubt on the unsupported assumption in the IRA that this is a common or accepted practice. Given that there are only 14 hatcheries in Australia, it should have been easy for Biosecurity Australia to have gathered information directly from each of these hatcheries about feeding practices, and to have determined whether the statements in the IRA about this risk were valid, or were mere conjecture. Advice from experienced people involved in prawn science and in practical prawn production is that this is not a practice adopted by commercial operators because it is unnecessary with modern feeds and it is risky with respect to endemic pathogens as well as exotic ones.

Much is made in the IRA of the ‘Darwin incident’, in which a research centre was diagnosed as infected with white spot virus. A number of aspects of this particular incident deserve independent scrutiny to test the validity of the conclusions which were drawn, but the issues are not central to this report and will not be considered further here. Suffice to say that the practices followed do not appear to accord with commercial farming practice, and it is most surprising that a research centre would follow the practices described briefly in the IRA. This incident is certainly not sufficient to justify rating the feeding of prawns to commercial broodstock as a common practice. The IRA provides no factual evidence to support its assessment of the importance of this pathway.

Given that there are only 14 hatcheries in the country, that they have a very large amount to lose if they become infected with exotic viruses, and that there is no nutritional justification for inclusion of raw prawns in rations based on modern feeding practices, if the practice is as risky as claimed then legislative control equivalent to the Australian swill feeding ban for pigs should have been introduced, especially since prawn farming is so geographically limited, and States which have been vocal about the

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risks posed by imported prawns should have used their existing powers to ban risky practices, then police the bans. The fact that no control measures have been introduced after some ten years of debate about prawn imports suggest strongly that this is not in fact seen as a significant practice in Australia, and hence no protective measures are considered by State governments to be required. It would appear from the evidence that the risk level attributed to this pathway is seriously over-stated.

3.4.2 Exposure through use of prawns as bait This is the other exposure pathway considered to be important in the IRA. In this case, quantitative evidence has been gathered through the first and second Kewagama reports titled National Survey of Bait and Berley Use by Recreational Fishers. The first of these reports has been reviewed, but the second has been withheld from us by Biosecurity Australia, although it is available to personnel within BA. A Freedom of Information Act request for release of the report has not been complied with prior to submission of this report. It is believed that the second report provides findings broadly similar to the first. Evaluation of the data in the first report shows that the quantity of imported prawns used as bait is small, the risks of exposure of both farmed and wild prawns is very low, and adoption of a 15 g minimum weight for imported prawns in 2001 will have made imported prawns less likely to be used as bait. In Policy Memorandum 2001/06 Biosecurity Australia committed to undertaking an education campaign to minimise use of prawns as bait, and to work with States and Territories towards imposing post-entry controls to prevent diversion of imported prawns for bait. The failure to implement an effective post-entry risk management system in accordance with that commitment within six years of officially undetaking to do so suggests that this is not seen as a significant biosecurity risk by the Australian government, although it is given considerable emphasis in the IRA.

3.5 Infectious dose of various agents The various mechanisms of exposure for the agents of concern include some for which exposure levels would be very low. All disease agents have a minimum infectious dose which is necessary to initiate infection of a host, and some of the exposure methods given considerable weight in the report (such as use of prawns as bait) are likely to very rarely if ever provide sufficient exposure to cause infection, even if the agent is present. The IRA gives inadequate consideration to whether material is likely to contain an infectious dose, as distinct from simply containing the agent.

3.6 Combining the partial risk estimates to determine annual risk The partial risk estimates were combined using a series of rules that assumed that each exposure group contributed an equal amount to the overall risk. This approach would be valid if the partial estimates of entry and exposure had been weighted by the relative volumes of potentially infected or contaminated prawns, and associated wastes, likely to be directed toward each exposure group and consequences had been weighted. However, as discussed above the method for assessing the relative volume of product did not provide information on how this was done, in a transparent manner. Therefore, we cannot assess if the combination of partial risk estimates was valid.

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3.7 Use of single qualitative value without sensitivity analysis Throughout the assessment a single qualitative value estimated by the Panel was selected to represent an often complicated pathway. In the unrestricted risk estimates for the hazards it was difficult to determine how the information was used to determine the final outcome(s) for the release, exposure and consequence assessments. No sensitivity analysis was conducted to show how robust the conclusions were, given the very subjective method by which values were assigned. This approach has resulted in a lack of transparency.

3.8 Consequence assessment The way in which the three quite different elements (likelihood of establishment, likelihood of exposure and biological/economic consequences ‘measured’ on a categorical scale) have been combined is not considered to provide a sound representation of the impact of exposure to each of the five agents of concern. Since Scenario 2 is a ‘non-event’ (since the agent disappears before its presence has even been discovered), this further complicates the interpretation of the evidence and its summarisation using Tables 3.3 and 3.4 and the associated decision rules (pp. 35-37).

Adding the further problem that products with quite widely different risk levels have been treated as a single product and all assigned the highest risk level, using volume of trade data in a way which is unclear, it can only be concluded that the unrestricted risk estimate provided in the IRA is not a balanced or accurate assessment of the true risk of establishment of the various agents, and that the unrestricted risk should be redone using a more appropriate analytical structure.

3.9 Evaluation of risk management strategies The structured risk analysis (as reported in the IRA) is limited to consideration of the unrestricted risk. The risk management strategies are not evaluated in an equivalent way within the same structure to determine whether their implementation would bring the risk below ALOP, or if this was done it is not reported and available for scrutiny. It appears to be simply assumed that the measures proposed are both necessary and sufficient to achieve ALOP. As shown below, this is invalid. The analysis should have included a pathogen-by-pathogen examination of the impact of potential risk management procedures on the overall risk and whether the managed risk fell below ALOP. It also appears that some risk management measures were discarded without proper evaluation, since when we evaluate them they are effective alone or in combination.

4: Hazard Identification

4.1 Coverage of hazards The hazard identification process is considered to be comprehensive. This section is essentially a series of tables. No text or scientific citations are provided to justify the conclusion that the identified hazards would be expected, or not expected, to cause significant disease in Australia. Whilst much of the necessary information is contained in Appendix 1, it is not possible to evaluate the reasoning underlying the assessment of impact.

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We conclude that retaining Taura syndrome virus (TSV) for risk assessment is debatable and further justification is required. Secondly, we consider that more detailed scrutiny of IHHNV is needed to determine whether it is justified to conclude that IHHNV is exotic to Australia, and, secondly whether evidence exists to conclude that disease would be significant. No additional hazards are proposed for consideration, beyond those identified in the IRA.

4.2 Taura syndrome virus TSV is a serious pathogen of P vannamei (Hasson et al., 1995). It is known to infect a range of penaeid species (Lightner, 1996) but has only caused serious commercial losses for juvenile to adult stages of P vannamei. In appendix 1 of the IRA, results of research commissioned by Biosecurity Australia into the susceptibility of several Australian crustacean species are briefly reported. Infection was only achieved by injection and not by oral challenge. Infections established by injection were not associated with significant mortality. P vannamei, the only species in which significant, commercial losses occur, is not cultured in Australia. On the basis of this evidence, it difficult to understand how a conclusion that TSV would be expected to cause significant disease in Australia is justified.

The agent will be considered in this report as eligible for risk management, but its eligibility requires further assessment for the final IRA, because its inclusion in the list for risk management is very questionable.

4.3 Infectious hypodermal and haematopoietic necrosis (IHHNV) IHHNV has an uncertain status as a hazard to Australian penaeid species. Australia is recognised as having IHHNV virus (Krabsetsve et al., 2004), however it is claimed that it is not the same strain that is present in New Caledonia, SE Asia and the Americas. The New Caledonian strain is thought to have originated from Mexican stock used to establish P stylirostris in the region in 1981. The Australian strain is considered to be relatively benign with few reports of epidemic disease associated with it. One report is given in Krabsetseve et al. (2004) of an epidemic of disease in a research facility where mortalities reached almost 100%. The SPS Agreement does not allow restriction in trade because of a disease unless the disease is either absent from a country or a disease control program is in place. The evidence that the Australian strain is different appears compelling when considering only the work of Owens et al. (1992), but when considered in the light of the findings of Tang and Lightner (2006), who demonstrated IHHNV sequences within the genotype of Australian and African prawns (Tang and Lightner, 2006), there is greater uncertainty as to the true meaning of these findings. There are other reports of PCR positive prawns from Thailand in the absence of clinical and histological signs of disease (Flegel et al., 2004). Therefore, it is at present unresolved whether Australia can adopt risk management measures for IHHNV, within the terms of the SPS Agreement.

Evidence is presented in Appendix 1 of the IRA to indicate that some Australian crustacean species are susceptible to IHNNV infection. However, recent papers (quoted in the Appendix) indicate that infection does not cause production losses in cultured P monodon (1986). No other evidence is cited to support the conclusion in Table 4.1 that IHNNV would be expected to cause significant disease.

The agent will be considered in this report as eligible for risk management, but its eligibility requires further assessment, as its inclusion is questionable.

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5: Available Risk Management Strategies The SPS Agreement expects that sanitary measures will be applied to reduce the assessed level of risk to below the country’s ALOP, but also requires that the measures chosen should be the least trade restrictive available.

The IRA states that ‘the least trade restrictive risk measures that could be applied to achieve Australia’s ALOP are evaluated’. No evidence is offered to support this claim, and it would appear that the evaluation was less than comprehensive, although measures evaluated were not documented adequately in the IRA, so this cannot be fully assessed. We have identified risk management options (discussed elsewhere in this report) that are less trade restrictive and more effective than those proposed in the IRA.

Furthermore, qualitative estimates for all the risk management strategies that were considered are not reported. For the selected strategies, a subjective judgement was made by the IRA Team as to whether the risk was reduced to ALOP. The change in LEE and LR was not estimated.

Inadequate consideration was given to the extent to which the various processed products might enter each of the identified exposure pathways and reach the various exposure groups, although a very high proportion of imported products are in processed form. The likelihood of exposure for processed products is even lower than whole prawns because they are of little value for bait or feeding to hatchery prawns, yet this is apparently not taken into account. However the section of the report dealing with agent-specific risk management is so brief that it cannot be evaluated in detail.

5.1 Cooking The report references work by Winkel (1998) in support of cooking to a core temperature of 85oC, although the work was totally unrelated to virus survival issues and did not consider that aspect. It is not an appropriate reference to cite in this context. There is evidence that cooking to this temperature produces an unmarketable product. In an industry survey of processors a core temperature of 70-75oC was found to be used. No evidence is presented to show the temperature/time combination required to kill the various viruses of interest, and the temperature of 85oC was seemingly chosen simply because it was considered (incorrectly) to be the industry standard. The requirement should be changed to reflect current practice. Cooking time and temperature are discussed further in relation to the unrestricted risk estimate for cooked prawns.

5.2 Testing Biosecurity Australia proposes a requirement for testing on arrival in Australia each batch of uncooked prawn meat or cutlets for White Spot Syndrome Virus (WSV), Yellow Head Virus and IHHNV by an AQIS approved laboratory, using PCR. Under this regimen only those batches that tested negative would be released for retail sale. The authors of the IRA concluded that there was considerable uncertainty in the sensitivity of the tests for prawn pathogens. Thus, this measure alone could not be relied upon to reduce the likelihood of release to a level that would sufficiently reduce the overall risk to an acceptable level.

The IRA states that a PCR molecular diagnostic test as recommended in the most current version of the OIE manual of diagnostic tests for aquatic animals (1996) should be used and the number of samples tested should provide 95% confidence of detecting

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20

the agent if present at 5% prevalence. The PCR diagnostic tests currently recognised by the OIE are outlined in Table 4.


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Table 4: OIE approved PCR tests for White Spot Syndrome Virus (WSSV), Yellow Head Virus and Infectious hypodermal and haematopoietic necrosis virus (IHHNV). Text extracted from the OIE Manual of Aquatic Animals. Pathogen Description of test Reference WWSV A positive result in the first step of this standard protocol implies a serious WSSV

infection; when a positive result is obtained in the second amplification step only, a latent or carrier-state infection is indicated. [It yields a first-step PCR amplicon of 1441 bp and a nested PCR amplicon of 941 bp].

Alternative assays have been described but are not recommended for use unless they have been compared with the protocol described here.

Lo et al (1997). Detection of baculovirus associated with white spot syndrome (WSBV) in penaeid shrimps using polymerase chain reaction. Dis. Aquat. Org., 25, 133-141

YHV Three RT-PCR methods are described. The first protocol is a 1-step RT-PCR adapted from Wongteerasupaya et al. (2004)that can be used for confirmation of YHV in shrimp collected from suspected YHD outbreaks. This protocol will detect only YHV and not GAV or other genotypes. The second protocol is a more sensitive multiplex RT-nested PCR procedure adapted from Cowley et al. (2003). It can be used for differential detection of YHV and GAV in disease outbreak shrimp or for screening of healthy carriers. This test will not detect all known genotypes in the yellowhead complex, and genotype 3 may react as GAV.

Wongteerasupaya C., et al. (1997). Detection of yellow-head virus (YHV) of Penaeus monodon by RT-PCR amplification. Dis. Aquat. Org., 31, 181-186 Cowley J.A., Cadogan L.C., Wongteerasupaya C., Hodgson R.A.J., Spann K.M., Boonsaeng V. & Walker P.J. (2004). Differential detection of gill-associated virus (GAV) from Australia and yellow head virus (YHV) from Thailand by multiplex RT-nested PCR. J. Virol. Methods, 117, 49-59.

IHHNV Several single step PCR methods are available for IHHNV detection. A number of commercial PCR kits are available for IHHNV detection. A nested method is also

Tang K.F.J. & Lightner D.V. (2001). Detection and quantification of infectious


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available, but only as a kit from a commercial source.

There are multiple geographical variants of IHHNV, some of which are not detected by all of the available methods for IHHNV. Two primer sets 392F/R and 389F/R appear to be the most suitable for detecting all the known genetic variants of IHHNV.

Hence, confirmation of unexpected positive and/or negative PCR results for IHHNV with a second primer set, or use of another diagnostic method (i.e. real time PCR, bioassay, ISH) is advisable).

hypodermal and hematopoietic necrosis virus in penaeid shrimp by real-time PCR. Dis. Aquat. Org., 44, 79-85. Tang K.F.J., Poulos B.T., Wang J., Redman R.M., Shih, H.H. & Lightner D.V. (1996) Geographic variations among infectious hypodermal and hematopoietic necrosis virus (IHHNV) isolates and characteristics of their infection. Dis. Aquat. Org., 53, 91-99.


Appendix 1 of the IRA briefly describes the diagnostic tests approved by OIE. Neither the main report nor the appendix makes any attempt to assess the test characteristics. However, uncertainty about test specificity and sensitivity is acknowledged (page 174):

Given uncertainty about the sensitivity of available tests for prawn pathogens, this option alone is not expected to reduce the likelihoods of entry and exposure sufficiently to reduce the overall risk to an acceptable level, but may be effective in combination with other measures.

The Australian AQUAVETPLAN for WSV gives considerable cautionary advice on the limitations of the PCR test, and states that it is hypersensitive and prone to misdiagnosis due to occurrence of false positives, and should always be confirmed by additional tests. The IRA reports but does not fully discuss the findings from a study by Claydon et al. (2004) which showed non-specific reactions to the WSV PCR test in native Australian crustacea, possibly due to a reaction with crustacean protein. It is unclear whether this can happen with overseas crustacea as well. AQUAVETPLAN states:

Polymerase chain reaction test

Although several different PCR protocols have been described for WSV, the OIE recommended technique is the nested PCR test of Lo et al. (1996) and Lo and Kou (1998). Details of the technique can be found in the original publications and in the OIE Aquatic Manual (OIE 2003a). Commercial PCR kits for the detection of WSV are also available from several suppliers.

Note: Eyes from prawns older than 10-day-old post-larvae must be excluded from tissue for analysis, as they are known to contain a PCR inhibitor. Care should be taken with the interpretation of results obtained with PCR, particularly when the test has been conducted on clinically normal animals. Repeat tests on a known infected specimen have resulted in both positive and negative results in some instances (Lo et al. 1997, Hsu et al. 1999), which may have been due to the concentration of WSV in the samples being close to the limit of the assay’s detection sensitivity. Furthermore, PCR-based assays cannot distinguish between live and dead virus.

Since Biosecurity Australia plans to require imported prawns to be tested for WSSV, YHV and IHHNV, it is a surprising omission that the tests have not been more fully evaluated in relation to both sensitivity and specificity, since use of a poorly specific test under the protocol proposed by Biosecurity Australia will almost certainly produce substantial numbers of rejections of batches which are not in fact infected. Under the SPS agreement, Australia is obliged to identify the least trade restrictive sanitary measures which will reduce the assessed risk to an acceptable level. The use of tests with poor specificity will result in consignments being incorrectly identified as infected, with consequent loss of trade. Testing may restrict trade in other ways. Neither the cost of testing nor the number of tests required (i.e. the number of imported batches) has been estimated, but high costs of dealing with false positive results may restrict trade. The report does not attempt to assess whether the physical and human resources required to test the current volume of imported prawns exists, or can be scaled up in a reasonable time frame, especially since the IRA proposes immediate implementation of the testing requirement. There are major doubts about whether sufficient testing resources could be put in place quickly, and trade may be severely restricted if testing capacity cannot meet the need in the short term. The proposed change in definition of a lot for testing purposes will exacerbate this problem.

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Considerable economic losses to the importer will result from any batch which yields a positive test result on arrival in Australia, and the testing requirement as proposed is likely to produce many false positive results and hence be highly trade restrictive, without necessarily reducing the risk of an incursion. Many PCR tests are recognized as very prone to false positives. These may be due to cross-reactions, to very small quantities of non-viable agent and to test repeatability issues. Therefore, the use of PCR tests in the regimen proposed by Biosecurity Australia may be very trade restrictive without being protective.

5.2.1 White Spot Syndrome Virus The reliability of the OIE approved PCR described by Lo et al. (2004), has been questioned by Claydon et al. (2006). Claydon et al. (2004) found that the nested amplicon, purportedly specific to WSSV, can be obtained from DNA abstracted from Cherax quadricarinatus (redclaw crayfish). They conclude that there is a lack of primer specificity for WSSV in the OIE test.

A comparison of PCR techniques for the detection of WSSV has been reported by Sritunyalucksana et al. (Cowley et al., 2004). The sensitivity of four tests (including that described by Lo et al, 1996) was compared against the Taqman quantitative PCR. However, the specificity of the PCR, and the question of cross-reaction with crustacean protein was not investigated.

PCR tests can detect as few as five copies of WSSV (Sritunyalucksana et al, 2006). It is therefore quite possible that the tests may detect a level of WSSV contamination that would be too low to result in the establishment of infection.

5.2.2 YellowHead Virus YHV is genetically closely related to GAV which is endemic in wild prawns (P monodon) in Queensland. It is important that the PCR used is able to distinguish YHV and GAV (Melena et al., 2006). Testing of prawns by an AQIS approved laboratory was proposed as a risk management strategy in the IRA. Under this regime only those batches that tested negative would be released for retail sale. The authors of the report concluded that there was considerable uncertainty in the sensitivity of the tests for prawn pathogens. Thus, this measure alone could not be relied upon to reduce the likelihood of release to a level that would sufficiently reduce the overall risk to an acceptable level.

5.2.3 Infectious hypodermal and haematopoietic necrosis virus There are numerous reports of test methodologies for testing of prawns for IHHNV. These all appear to be experimental, used in research projects, rather than validated commercial testing regimens. Furthermore, Tang and Lightner (2006) found that the black tiger prawn Penaeus monodon may in some instances contain sequences from the virus in the genome of the prawn. As the report correctly concludes:

Screening by current PCR methods, such as those recommended by the World Animal Health Organisation, will yield false positives for samples containing type A and B IHHNV related sequences; because the commonly used primers cannot differentiate between these and the actual virus.

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It is vitally important to distinguish between the infectious and non infectious types of IHHNV as the latter are of no consequence to trade. Indeed they may even be useful, as various authors have identified that prior exposure of prawns (e.g. P vannamei) to IHHNV or inactivated WSSV can induce a level of immunity to infection by WSSV (Durand et al., 2003)

The IRA makes the briefest mention in passing about the finding of IHHNV sequences in the genome of P. monodon and no mention of the implications for large scale testing as proposed.

5.3 Highly processed prawns The report does not consider that marinated prawns are ‘highly processed’. The volume of highly processed prawns entering any of the exposure routes identified will be negligible. The arguments applied to the highly processed products identified (e.g. breaded, battered etc.) apply equally to marinated prawns (for example, their higher prices will mean that they are unlikely to be purchased by recreational fishermen for bait or berley). Therefore, we consider that marinated prawns should be included in the definition of ‘highly processed’.

6: Product-Specific Assessment of Unrestricted Risk As indicated earlier, it is inappropriate to consider all prawn products to have an unrestricted risk equivalent to whole uncooked prawns. Therefore, the unrestricted risk for processed prawn products will now be considered to determine their individual unrestricted risks, and whether any risk management measures are necessary.

7: Unrestricted Risk Estimate for Uncooked Prawn Cutlets

7.1 Introduction Prawn cutlets are defined for the purpose of this risk analysis as having the head removed and the shell removed to the last tail segment, but with the tail still present. Some prawn cutlets may have been butterfly cut thus removing their vein. These cutlets are considered lower risk (by a significant margin) than whole uncooked prawns because the high risk organs and shell have been removed during processing. It is important to recognise that during processing, the uncooked whole prawn and the resulting cutlets have been inspected for signs of disease (with rejection of unsuitable product) and washed with chlorinated water (at least 10 ppm)

Biosecurity Australia considered head and shell removal as a risk mitigation strategy. They concluded that it was adequate for managing the risk of TSV and necrotising hepatopancreatitis bacterium, but not for WSSV, IHHNV and YHV. It was acknowledged that head and shell removal reduces both the amount of pathogen released and the likelihood of exposure. However, the report does not provide the restricted risk estimates for release or exposure (i.e. the estimates after risk management is applied). There is no evidence of detailed consideration of how prawn cutlets (i.e. prawns with the head and shell removed) could enter any of the three exposure pathways identified, and thus lead to exposure of either farmed, hatchery or wild crustaceans. Similarly the volume of trade in cutlets is not mentioned, although figures are available. In this respect the report clearly fails to meet the criterion of transparency. It is therefore impossible to evaluate how Biosecurity Australia arrived at

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the conclusion that ALOP was still exceeded for WSSV, IHHNV and YHV but not for TSV and necrotising hepatopancreatitis bacterium.

Since it is inappropriate to consider all prawn products to have an unrestricted risk equivalent to whole uncooked prawns, we have estimated the unrestricted risk for uncooked prawn cutlets. The risk estimate for uncooked prawn cutlets is effectively equivalent to examining head and shell removal as a risk mitigation strategy. Only WSSV, IHHNV and YHV are considered since these pathogens potentially require further risk management.

7.2 Method The unrestricted risk was estimated for the annual likelihood of release and the partial likelihood of exposure for farm (exposure group 1), hatchery (exposure group 2) and wild crustaceans (exposure group 3). Using the methodology described in the IRA for prawn and prawn products these values were combined to calculate the partial annual likelihood of entry and exposure (PALEE) for each of the exposure groups. The PALEE was then combined with the ‘likely consequences’ of exposure in each group. This information was then used to calculate the unrestricted risk for uncooked prawn cutlets.

7.3 Unrestricted risk estimate for individual hazards

7.3.1 White spot syndrome virus

Release assessment Removal of the cephalothorax reduces the viral load by approximately 50% compared with whole raw green prawns (1999). The virus is highly stable in the in the fresh or frozen product. The amount of virus released will be lower than whole uncooked prawns. The reduction in virus will reduce the levels of released virus, which will reduce the probability of exposure and establishment.

Exposure assessment The IRA identified three significant exposure pathways: (a) use of prawns as bait or berley; (b) use of prawns as feed to condition broodstock; and (c) untreated waste disposal following commercial processing of prawns for human consumption.

As acknowledged in the IRA, head (i.e. the cephalothorax) and shell removal would reduce the unintended end use of prawns both as bait or berley and as feed to condition broodstock. Prawn cutlets are not suitable as broodstock feed because (a) the head and shell contain valuable nutrients for broodstock; and (b) cutlets are more expensive that unprocessed prawns. Similarly, due to a preference for whole uncooked prawns and price considerations, little of the product, destined for human consumption, will be diverted for use as bait. Susceptible species of crustaceans can become infected orally (Flegel et al., 1995a). However, prawns are used as bait for finfish and therefore the likelihood that an infectious dose will be ingested by a susceptible crustacean is very low. The likelihood of transmission via seawater, from prawns used as bait, is negligible due to dilution.

The IRA stated that processing could include removal of the head, removal of head and shell and further processing such as coating, marinating or crumbing. Given that the

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head and shell have already been removed from uncooked prawn cutlets, further processing would be extremely limited. The IRA quotes ADVS (Boonsaeng et al., 2000) where it is concluded that very little processing of imported prawns takes place in Australia. Only low volumes of untreated waste would be generated. Furthermore, any waste (solid or liquid) would contain a very low level of contamination since a large portion of the pathogen load is located in the cephalothorax and shell. The amount of WSSV released into the environment following processing of uncooked prawn cutlets poses a negligible risk.

Given these considerations, the PLE of WSSV from the unrestricted importation of frozen, uncooked prawn cutlets is negligible, extremely low and negligible for farmed, hatchery and wild crustaceans, respectively.

Determination of the partial annual likelihood of entry and exposure The PALEE for the farmed, hatchery and wild crustacean exposure groups were negligible, extremely low and negligible, respectively.

Conclusion The unrestricted risk associated with WSSV is determined to be negligible. The unrestricted risk estimate achieves Australia’s ALOP, no risk management strategy is considered necessary.

7.3.2 Yellowhead virus

Release assessment Removal of the cephalothorax reduces the viral load compared with whole raw green pawns, however, no data is available to estimate the reduction The IRA provides no information on the tissue titre of yellowhead virus; but the lack of data was not identified as an issue in the report. The virus is highly stable in the fresh or frozen product. The probability of release, on a consignment basis, will be reduced since the amount of virus released will be reduced in comparison with green prawns. The likelihood of exposure and establishment is positively correlated with the amount of virus released.

Exposure assessment The discussion of exposure for WSSV applies equally to YHV, notably that (a) there will be only very limited processing of prawn cutlets; (b) prawn cutlets are not suitable as broodstock feed; and (c) due to preference for whole green prawns and price considerations, very little of the product, destined for human consumption, will be diverted for use as bait.

Some evidence exists to concluded that susceptible species of crustacean may become infected per os (van de Braak et al., 2002) (though susceptibility of P monodon is age dependent). The susceptibility of large crustaceans (e.g. crabs), to per os infection has not been tested (only experimental infections have been successful (Tang and Lightner, 2002)). However, since prawns are used a bait for finfish, the likelihood that an infectious dose will be ingested by a susceptible crustacean is very low. The likelihood of transmission via seawater, from prawns used as bait, is negligible due to dilution.

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Based on these considerations the PLE to YHV from the unrestricted importation of uncooked prawn cutlets (with head and shell removed) is negligible for both farmed and wild crustaceans and extremely low for hatchery crustaceans.

Determination of the partial annual likelihood of entry and exposure The PALEE for the farmed, hatchery and wild crustacean exposure groups was negligible, extremely low and negligible, respectively (Table 5). Therefore, the partial risk was negligible for each farmed and wild crustaceans and very low for the hatchery exposure group.

Conclusion Therefore, the unrestricted risk associated with YHV is determined to be very low. As the unrestricted risk estimate achieves Australia’s ALOP, no risk management strategy is considered necessary.

7.3.3 Infectious hypodermal and haematopoietic necrosis virus

Release assessment Removal of the cephalothorax reduces the viral load compared with whole raw green prawns, however, no data are available to estimate the reduction. In the absence of information regarding the titre of various tissues, and how these relate to an infectious dose, likelihood of release can be considered lower for prawns with a proportion of tissue(s) removed which could reasonably be considered more highly infectious because of the role of the lymphoid organ within the head in removing foreign material (Lightner et al., 1983). On this basis we consider the likelihood of release is moderate (i.e. an even probability). The amount of virus released will be reduced (compared with uncooked whole prawns). Lower levels of released virus will reduce the probability of exposure and establishment. The virus is highly stable in the fresh or frozen product (OIE, 2006a).

Exposure assessment The discussion of exposure for WSSV and YHV applies equally to IHHNV, notably that (a) there will be only very limited processing of prawn cutlets; (b) prawn cutlets are not suitable as broodstock feed; and (c) due to preference for whole green prawns and price considerations, very little of the product, destined for human consumption, will be diverted for use as bait. In addition, prawns are used a bait for finfish and, therefore, the likelihood that an infectious dose will be ingested by a susceptible crustacean is very low. The likelihood of transmission via seawater, from prawns used as bait, is negligible due to dilution. Furthermore, research has demonstrated that prolonged exposure to high doses of IHHNV is required to achieve infection during co-culture (Durand et al., 2003). It is effectively impossible for these conditions to be met via the exposure pathways identified.

Based on these considerations the PLE to IHHNV from the unrestricted importation of uncooked prawn cutlets with head and shell is negligible for both farmed and wild crustaceans and extremely low for hatchery crustaceans.

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Determination of the partial annual likelihood of entry and exposure PALEE was negligible for farmed and wild crustaceans and extremely low for the hatchery exposure group. When combined with the likely consequence the partial annual risk was negligible for farmed and wild crustaceans and extremely low for the hatchery exposure group.

Conclusion Therefore, the unrestricted risk associated with IHHNV is determined to be very low. As the unrestricted risk estimate achieves Australia’s ALOP, no risk management strategy is considered necessary.

7.4 Sensitivity analysis The annual risk associated with the importation of prawn cutlets was found to be below ALOP (i.e., negligible) based on the following estimates for likelihood of release (LR) and partial likelihood of exposure (PLE) for WSSV, IHHNV and YHV:

LR: moderate

PLE farm exposure group (1): negligible

PLE hatchery exposure group (2): negligible

PLE wild exposure group (3): very low

If we assume that the likelihood of release, after head and shell removal, remained high, the risk associated with WSSV, IHHNV and YHV would still be very low. Therefore, altering the likelihood of release, while holding all others constant, does not impact on the final assessment (i.e. ALOP is not exceeded and no risk management is required). In contrast, altering the partial likelihood of exposure in each of the groups, while holding the other values constant, would alter the annual risk. Sensitivity analysis found that if the PLE for either the farm and hatchery crustacean groups was very low (rather than negligible) that the annual risk (calculated by combining the three exposure groups) would be low, and, therefore exceed ALOP. Similarly, if the PLE for the wild group was moderate rather than very low, then the annual risk would be low, and, therefore exceed ALOP.

7.5 Conclusion The risk assessment method used by Biosecurity Australia has been applied in this section to importation of prawn cutlets (non-viable, farm sourced, frozen, uncooked prawns with head and shell removed, excluding the last tail segment). This is broadly equivalent to the restricted risk assessment Biosecurity Australia presumably conducted for head and shell removal. Our results show that risk management strategies are not required for the importation of prawn cutlets since the annual risk for all the hazards considered in this assessment was below Australia’s ALOP. While the other hazards identified in the IRA were not specifically considered in our unrestricted risk for reasons discussed in the introduction, we contend that the unrestricted risk for these agents would also fall below ALOP. Therefore, prawn cutlets should be imported without any risk management strategy.

Compared with whole green prawns, cutlets are clearly a considerably less risky product. The removal of head and shell reduces the amount of pathogen released (by at least 50%). The risk of exposure is also greatly reduced. Demonstrating that routes

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exist for the hazard to gain entry to the aquatic environment is only the first step in the exposure assessment. The infectious dose and availability of susceptible hosts have to be considered to determine if exposure will lead to infection, and (according to the OIE Aquatic Animal Health Code) spread and establishment of the hazard (Flegel et al., 1995a). Cutlets will lead to negligible exposure via waste water or as prawn feed. The use of bait and berley presents a potential route of exposure, but it has not cited as route of spread of crustacean disease. In addition, very low volumes of imported cutlets might be used as bait or berley. The probability that a susceptible crustacean could ingest an infectious dose from a cutlet, through its use as bait or berley, is extremely small

Biosecurity Australia’s IRA concluded that head and shell removal did not reduce the annual risk to ALOP, their analysis is, therefore, at variance with our results. Since Biosecurity Australia did not provide any information on the restricted risk estimations for release and exposure (i.e following head and shell removal), it is not possible to determine why they concluded head and shell removal did not reduce the annual risk to ALOP. It is likely that the difference is because we consider that head and shell removal will reduce the likelihood of exposure by reducing the amount of material going through the major risk pathways, whereas we assume that Biosecurity Australia did not allow for this reduction, despite the evidence that there would be a reduction.

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Table 5: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when uncooked prawn cutletsa are imported without restriction.

Agent Exposure group Variable WSSVb IHHNVc YHVd

Farm LR Moderate Moderate Moderate PLE Negligible Negligible Negligible PALEE Negligible Negligible Negligible Likely Consequences High High High Partial Risk Negligible Negligible Negligible Hatchery LR Moderate Moderate Moderate PLE Extremely low Extremely low Extremely low PALEE Extremely low Extremely low Extremely low Likely Consequences High High High Partial Risk Very low Very low Very low Wild LR Moderate Moderate Moderate PLE Negligible Negligible Negligible PALEE Very low Very low Very low Likely Consequences Low Low Low Partial Risk Negligible Negligible Negligible All Annual Risk Very low Very low Very low

a Prawn with head removed and the shell up to but not including the last tail segment removed b White spot syndrome virus c Yellowhead virus d Infectious hypodermal and haematopoietic necrosis virus

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8: Unrestricted Risk Estimate for Uncooked Prawn Meat

8.1 Introduction Prawn meat is defined for the purpose of this risk analysis as having the head and shell removed, including the tail segment. It is therefore a similar product to prawn cutlets, except that since cutlets retain the last tail segment, they are a very slightly higher risk product. Some prawns may have been butterfly cut, thus removing their vein. This meat is considered lower risk (by a substantial margin) than whole green prawns because the high risk organs have been removed during processing. It is important to recognise that during the processing, the whole green prawn and the resulting meat have been inspected for signs of disease (with rejection of unsuitable product) and washed with chlorinated water (at least 10 ppm).

Unrestricted risk estimates were not undertaken in the IRA for TSV and necrotising hepatopancreatitis bacterium because Biosecurity Australia found that head and shell removal reduced the PALEE for farmed and hatchery groups to negligible and that of the wild group to at least very low, thus reducing the annual risk to below ALOP. The risk associated with hepatopancreatic parvovius, infectious myonecrosis virus, Baculovirus penaei, and Vibrio penaecidia via the unrestricted importation of uncooked whole prawns meat intended for human consumption was below ALOP. Given that whole uncooked prawns are a higher risk product that uncooked prawn meat, it is reasonable to expect that the risk estimates for these hazards associated with the unrestricted importation of uncooked prawn meat would also be below ALOP. Therefore, we limited our analysis to the risk of introduction of WSSV, IHHNV and YHV, as a result of unrestricted importation of uncooked prawn meat.

8.2 Method The unrestricted risk was estimated for the annual likelihood of release and the partial likelihood of exposure for farm (exposure group 1), hatchery (exposure group 2) and wild crustaceans (exposure group 3). Using the methodology described in the Biosecurity Australia IRA for prawn and prawn products these values were combined to calculate the partial annual likelihood of entry and exposure (PALEE) for each of the exposure groups. The PALEE was then combined with the ‘likely consequences’ of exposure in each group. This information was then used to calculate the unrestricted risk for uncooked prawn cutlets.

8.3 Unrestricted risk estimate for individual hazards

8.3.1 White spot syndrome virus

Release assessment Removal of the cephalothorax and the tail shell reduces the viral load by approximately 77% compared with whole green prawns (Boonsaeng et al., 2000). The virus is highly stable in the in fresh or frozen product. The probability of release, on a consignment basis, will be reduced since the amount of virus released will be reduced (compared with green prawns). The likelihood of exposure and establishment is positively correlated with the amount of virus released.

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Exposure assessment The IRA identified three significant exposure pathways: (a) use of prawns as bait or berley; (b) use of prawns as feed to condition broodstock; and (c) untreated waste disposal following commercial processing of prawns for human consumption.

Firstly, prawn meat will not be further processed in Australia. Secondly, prawn cutlets are not suitable as broodstock feed because (a) the head and shell contain valuable nutrients for broodstock; and (b) prawn meat is more expensive that unprocessed prawns. Similarly, due to a preference for whole uncooked prawns and price considerations, little of the product, destined for human consumption, will be diverted for use as bait. Susceptible species of crustacean can become infected per os (van de Braak et al., 2002); however, prawns are used as bait for finfish and therefore the likelihood that an infectious dose will be ingested by a susceptible crustacean is very low. The likelihood of transmission via seawater, from prawns used as bait is negligible due to dilution.

The IRA stated that processing could include removal of the head, removal of head and shell and further processing such as coating, marinating or crumbing. Given that the head and shell has already been removed from uncooked prawn meat, further processing would be extremely limited, and for this reason the volume of untreated waste would be substantially reduced. In addition, a large portion of the viral load is located in the head and shoulders so the amount of WSSV released into the environment following processing of uncooked prawn meat would be significantly less than for uncooked whole prawns.

Given these considerations the PLE of WSSV from the unrestricted importation of frozen, uncooked prawn meat is negligible, extremely low and negligible for farmed, hatchery and wild crustaceans, respectively.

Determination of the partial annual likelihood of entry and exposure The PALEE for the farmed, hatchery and wild crustacean exposure groups were negligible, extremely low and negligible, respectively (Table 5).

Conclusion The unrestricted risk associated with WSSV is determined to be negligible. The unrestricted risk estimate achieves Australia’s ALOP, no risk management strategy is considered necessary when importing uncooked prawn meat.

8.3.2 Yellowhead virus

Release assessment Removal of the cephalothorax reduces the viral load compared with whole raw green pawns, however, no data is available to estimate the reduction The IRA provides no information on the tissue titre of yellowhead virus; the lack of data was not identified in the report. The virus is highly stable in the in the fresh or frozen product. The probability of release, on a consignment basis, will be reduced since the amount of virus released will be reduced (compared with green prawns). The likelihood of exposure and establishment is positively correlated with the amount of virus released.

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Exposure assessment The discussion of exposure for WSSV applies equally to YHV, notably that (a) prawn meat will not be further processed in Australia; (b) prawn meat is not suitable as broodstock feed; and (c) due to preference for whole green prawns and price considerations, very little of the product, destined for human consumption, will be diverted for use as bait. Some evidence exists to conclude that susceptible species of crustacean may become infected per os (Lightner et al., 1983) (though susceptibility of P monodon is age dependent). The susceptibility of large crustaceans (e.g. crabs), to per os infection has not been tested (only experimental infections have been successful (Winkel, 1986)). However, since prawns are used a bait for finfish, the likelihood that an infectious dose will be ingested by a susceptible crustacean is very low. The likelihood of transmission via seawater, from prawns used as bait, is negligible due to dilution.

Based on these considerations the PLE to YHV from the unrestricted importation of uncooked prawn meat (with head and shell removed) is negligible for both farmed and wild crustaceans and extremely low for hatchery crustaceans.

Determination of the partial annual likelihood of entry and exposure The PALEE for the farmed, hatchery and wild crustacean exposure groups was negligible, extremely low and negligible, respectively (Table 5). Therefore, the partial risk was negligible for each farmed and wild crustaceans and very low for the hatchery exposure group.

Conclusion Therefore, the unrestricted risk associated with YHV is determined to be very low. As the unrestricted risk estimate achieves Australia’s ALOP, no risk management strategy is considered necessary when importing uncooked prawn meat.

8.3.3 Infectious hypodermal and haematopoietic necrosis virus

Release assessment In the absence of information regarding the titre of various tissues, and how these relate to an infectious dose, likelihood of release can be considered lower for prawns with a proportion of tissue(s) removed which could reasonably be considered more highly infectious because of the role of the lymphoid organ within the head in removing foreign material (Chang et al., 1998). On this basis we consider the likelihood of release is moderate (i.e. an even probability).

Exposure assessment The discussion of exposure for WSSV and YHV applies equally to IHHNV, notably that (a) prawn meat will not be further processed in Australia; (b) prawn meat is not suitable as broodstock feed; and (c) due to preference for whole green prawns and price considerations, very little of the product, destined for human consumption, will be diverted for use as bait. In addition, prawns are used a bait for finfish and, therefore, the likelihood that an infectious dose will be ingested by a susceptible crustacean is very

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low. The likelihood of transmission via seawater, from prawns used as bait, is negligible due to dilution. Furthermore, research has demonstrated that prolonged exposure to high doses of IHHNV is required to achieve infection during co-culture (Flegel et al., 1995b). It is effectively impossible for these conditions to be met via the exposure pathways identified.

Based on these considerations the PLE to IHHNV from the unrestricted importation of uncooked prawn meat (with head and shell removed) is negligible for both farmed and wild crustaceans and extremely low for hatchery crustaceans.

Determination of the partial annual likelihood of entry and exposure For PALEE was negligible for farmed and wild crustaceans and extremely low for the hatchery exposure group. When combine with the likely consequence the partial annual risk was negligible for farmed and wild crustaceans and extremely low for the hatchery exposure group.

Conclusion Therefore, the unrestricted risk associated with IHHNV is determined to be very low. As the unrestricted risk estimate achieves Australia’s ALOP, no risk management strategy is considered necessary.

8.4 Sensitivity analysis Given that the input values for prawn meat were the same as those selected for prawn cutlets, the results of the sensitivity analysis described for cutlets applies equally to prawn meat. In summary, altering the likelihood of release will not impact on the final assessment. In contrast, if the PLE for either the farm and hatchery crustacean groups was very low (rather than negligible) then the annual risk would be low, and, therefore exceed ALOP. Similarly, if the PLE for the wild group was moderate rather than very low then the annual risk (calculated by combining the three exposure groups) would be low, and, therefore exceed ALOP.

8.5 Conclusion The results of this section are identical to the analysis presented in section 7, and the same conclusions can be drawn. Prawn meat is a slightly lower risk product than prawn cutlets since the last tail segment is retained in the latter. However, this difference was not sufficient to change any of the qualitative risk estimations. Therefore, in addition to prawn cutlets, it is also concluded that risk management strategies are not required for control of any of WSSV, YHV and IHHNV when importing uncooked prawn meat. While, the other hazards identified in the IRA were not specifically considered in our unrestricted risk for reasons discussed in the introduction, we agree with Biosecurity Australia that the unrestricted risk for these agents would also fall below ALOP. Therefore, prawn meat should be imported without any risk management strategy.

9: Unrestricted Risk Estimate for Cooked Prawns

9.1 Introduction Biosecurity Australia indicated that prawns could be permitted entry subject to:

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cooking off-shore in a premises approved by, and under the control of, the Competent Authority to ensure inactivation of the pathogenic agent of concern, and subject to verification by the overseas Competent Authority. Alternatively, prawns could be cooked post-arrival at quarantine approved premises.

The report proposes that a core temperature of 85oC be required during cooking. No evidence is provided to support the necessity to achieve this temperature, and no time/temperature combinations are provided, although these are far more relevant than simple core temperatures. Experience from industry (in contrast to the Winkel report (Leblanc and Overstreet, 1991)) is that cooking to a core temperature of 85oC results in a product that is not marketable. There appears to be no basis for raising the temperature above the current recommendations for those required by USFDA requirements for elimination of L monocytogenes. These guidelines recommend that the prawns are cooked for 17 minutes at 63oC or one minute at 72oC. It is worth noting that the times are highly dependent on the size of the prawn. The current common practice in Asia for whole prawns and the only practice for peeled prawns is steam cooking or boiling. Core temperature is checked routinely, and the minimum core temperature ranges from 700C to 750C. Thus the following combinations are proposed as providing marketable product, while still expected to achieve deactivation of prawn pathogens:

Size 16/20 3.00 min at 75oC Size 20/30 2:15 min at 75oC. Size 30/40 2:00 min at 75oC.

Specific information by disease agent is as follows.

9.1.1 White spot syndrome virus Cooking for 5 minutes at 70oC in sterile water inactivates WSSV in a sterile solution . There is considerable uncertainty about the effect of cooking on the inactivation of WSSV virus in biological material. Due to this uncertainty, the AQUAVETPLAN recommends cooking for 20 minutes at 60oC to ensure inactivation of WSSV. The required cooking temperature of 85oC required in the risk mitigation measure is not based on sound evidence that this temperature inactivates WSSV (or other pathogens).

Cooking does not need to completely eliminate WSSV for the likelihood of entry and exposure of WSSV to be reduced to an acceptable level (i.e. very low). Cooking at 700C to 750C will undoubtedly reduce the viral load and therefore the amount of released pathogen. Cooked prawns are very unlikely to be diverted down any of the three exposure pathways identified in the IRA in significant quantities. They are highly unlikely to go for further processing (and any processing would not produce contaminated waste), or be fed to farmed broodstock. A very low volume of cooked prawns may be used as bait and result in a very low level of exposure. Cooking will reduce the pathogen load, and the likelihood of ingestion of an infectious dose of cooked product is greatly reduced.

Likelihood of release: Moderate Likelihood of exposure wild: Extremely Low Likelihood of exposure hatchery: Negligible Likelihood of exposure farmed: Negligible

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9.1.2 Yellow head virus Research in Thailand has shown that YHV extracts are inactivated by heating at 60oC for 15 minutes. There is a lack of data on which to estimate the effect of cooking on the inactivation of YHV in biological material. The required cooking temperature of 85oC required in the risk mitigation measure is not based on sound evidence that this temperature inactivates yellowhead virus (or other pathogens). Currently the evidence does not exist on which to estimate the reduction in viral titre that may be achieved at different cooking temperatures. Other factors such as the size of the prawn and the method of cooking are also important.

Cooking does not need to completely eliminate YHV for the likelihood of entry and exposure to be reduced to an acceptable level (i.e., very low). Cooking at 700C to 750C will undoubtedly reduce the viral load and therefore the amount of released pathogen. Cooked prawns are very unlikely to be diverted down any of the three exposure pathways identified in the IRA in significant quantities. They are highly unlikely to go for further processing (and any processing would no produce contaminated waste), or be fed to farmed broodstock. A very low volume of cooked prawns may be used as bait and result in a very low level of exposure. Cooking will reduce the pathogen load and the likelihood of ingestion of an infectious dose is greatly reduced.


9.1.3 IHHNV There is a lack of data on which to estimate the effect of cooking on the inactivation of IHHNV in biological material. The cooking temperature of 85oC required in the risk mitigation measure is not based on sound evidence that this temperature inactivates IHHNV (or other pathogens). Currently the evidence does not exist on which to estimate the reduction in viral titre that may be achieved at different cooking temperatures. Other factors such as the size of the prawn and the method of cooking are also important.

Cooking does not need to completely eliminate IHHNV for the likelihood of entry and exposure to be reduced to an acceptable level (i.e. very low). Cooking at 700C to 750C will undoubtedly reduce the viral load and therefore the amount of released pathogen. Cooked prawns are very unlikely to be diverted down any of the three exposure pathways identified in the IRA in significant quantities. They are highly unlikely to go for further processing (and any processing would not produce contaminated waste), or be fed to farmed broodstock. A very low volume of cooked prawns may be used as bait and result in a very low level of exposure. Cooking will reduce the pathogen load and the likelihood of ingestion of an infectious dose is greatly reduced.


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9.1.4 TSV There is a lack of data on which to estimate the effect of cooking on the inactivation of TSV in biological material. The required cooking temperature of 85oC required in the risk mitigation measure is not based on sound evidence that this temperature inactivates TSV (or other pathogens). Currently the evidence does not exist on which to estimate the reduction in viral titre that may be achieved at different cooking temperatures. Other factors such as the size of the prawn and the method of cooking are also important.

Cooking does not need to completely eliminate TSV for the likelihood of entry and exposure to be reduced to an acceptable level (i.e. very low). Cooking at 700C to 750C will undoubtedly reduce the viral load and therefore the amount of released pathogen. Cooked prawns are very unlikely to be diverted down any of the three exposure pathways identified in the IRA in significant quantities. They are highly unlikely to go for further processing (and any processing would not produce contaminated waste), or be fed to farmed broodstock. A very low volume of cooked prawns may be used as bait and result in a very low level of exposure. Cooking will reduce the pathogen load and the likelihood of ingestion of an infectious dose is greatly reduced.


9.1.5 Tetrahedral baculovirus - baculovirus penai (BP) BP can become inactivated by heating for 10 minutes in water baths at 60oC to 90oC. Cooking, therefore, to a core temperature of 70oC, the current standard will achieve a considerable decrease in the pathogen load. Cooking does not need to completely eliminate BP for the likelihood of entry and exposure to be reduced to an acceptable level (i.e. very low). Cooking at 700C to 750C will undoubtedly reduce the viral load and therefore the amount of released pathogen. Cooked prawns are very unlikely to be diverted down any of the three exposure pathways identified in the IRA in significant quantities. They are highly unlikely to go for further processing (and any processing would no produce contaminated waste), or be fed to farmed broodstock. A very low volume of cooked prawns may be used as bait and result in a very low level of exposure. Cooking will reduce the pathogen load and the likelihood of ingestion of an infectious dose is greatly reduced.


9.2 Conclusion It is concluded that no risk management measures are required for cooked or other highly processed prawn products.

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10: Risk Management for Uncooked Whole Prawns The only product category for which risk management measures are considered necessary is whole uncooked prawns, (including head-off shell-on uncooked prawns). Various alternative risk management measures will now be evaluated, after first examining to which factors the outcome is sensitive.

10.1 Sensitivity analysis According to the rules for combining partial risks in order for the annual risk to be at least very low, and, therefore below ALOP the partial risk in two of the three exposure groups must be very low and the partial risk in the third group must negligible. This means ALOP can only be achieved if the:

Partial risk in farmed and hatchery crustaceans is reduced to very low and the partial risk in the wild crustacean exposure group is negligible; or Partial risk in farmed and wild crustaceans is very low and the partial risk in the hatchery crustacean exposure group is negligible; or Partial risk in hatchery and wild crustaceans is very low and the partial risk in the farmed crustacean exposure group is negligible; or Partial risk in farmed, hatchery and wild crustaceans exposure groups is negligible.

If we assume that all risk management strategies will do nothing to alter the consequences in each exposure group, the only option is to reduce the PLEE. The reduction that is required depends on the pathogenic agent. Given that the likely consequences are hazard dependent the minimum change in PLEE will differ between the pathogenic agents. For WSSV, YHV and IHHNV the combination that would require the least changes to the unrestricted risk would be to reduce the partial risk in the wild group to negligible and the risk in the hatchery and farmed to very low. In the farm and hatchery crustacean exposure groups the likely consequences associated with each of these agents was high, and, as such to reduce the partial risk in these exposure groups to very low the PLEE would have to decrease to at least extremely low. This could be achieved by:

reducing the likelihood of release to extremely low; or reducing the partial likelihood of exposure to extremely low; or reducing the likelihood of release and partial likelihood of exposure to very low.

To reduce the partial risk in the wild crustacean group from low to negligible the PALEE would need to decrease to at least very low. This could be achieved by:

reducing the likelihood of release to very low; or reducing the partial likelihood of exposure to very low; or reducing both the likelihood of release and partial likelihood of exposure to low.

For TSV the annual risk would be below ALOP if the risk for any of the three exposure groups decreased from very low to negligible. This could be achieved by reducing the PLEE in one of these groups to at least extremely low. This could be done by:

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reducing either the likelihood of release to extremely low; or reducing the partial likelihood of exposure to extremely low; or reducing both the likelihood of release and partial likelihood of exposure to very low.

For NHPB the combination that would require the least modification from the unrestricted risk estimate is to reduce the partial risk to very low in the farmed and hatchery groups and to negligible in the wild crustacean group. In the farm and hatchery crustacean exposure group the likely consequences associated with each of these agents was moderate, and, as such to reduce the partial risk in these exposure groups to very low the PLEE would have to decrease to at least very low. This could be achieved by:

reducing the likelihood of release to very low; or reducing the partial likelihood of exposure to very low; or reducing both the likelihood of release and partial likelihood of exposure to low

Given that IRA estimates the ‘likely consequences’ associated with NHNB in the wild crustacean group to be low to reduce the partial risk in this group to negligible the PALEE would need to decrease to at least very low. This could be achieved by:

reducing the likelihood of release to very low; or reducing the partial likelihood of exposure to very low; or reducing both the likelihood of release and partial likelihood of exposure to low.

10.2 Risk management options

10.2.1 Removing the head Under this strategy uncooked prawns could only be imported if the head was removed prior to arrival at an Australian port. Figure 1 shows the parts of a Penaeid prawn body. The ‘head’ of the prawn contains the lymphoid organ which is where a significant proportion of phagocytosed virus material is located. Thus, removal of the head is a simple risk mitigation that results in no loss of edible product.

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Figure 1: Parts of the body of Penaeid prawn.

Release assessment Removal of the head of a prawn will result in removal of the lymphoid organ. Van de Braak et al. (2002a) presented information showing that the lymphoid organ plays an important role in removing a variety of foreign material including viral and bacterial materials, aflatoxin and carbon particles from the haemolymph before it travels from the arterial system into the open circulatory system. Thus, removal of the head is extremely likely to result in a reduction in the viral load in imported prawns. It will, however, not completely remove the viral load from the imported products as the virus may still be present in the meat and shell. Given this information the annual likelihood of release for each of the pathogens was not altered from the values used in the unrestricted risk estimate (i.e., the likelihood of release was high for each of the five pathogens).

Exposure assessment Removal of the head could alter the volume of contaminated product that is diverted down exposure pathways. Firstly, removal of the head prior to importation would significantly reduce the volume of waste produced in commercial processing of imported prawns, thereby reducing the likelihood of the wild group being exposed to prawn pathogens. Secondly, the viral load in infected uncooked prawns with heads removed would be less than in uncooked whole prawns. Therefore, if any of crustaceans were exposed to an imported prawn they would be less likely to receive an infectious dose. Thirdly, the volume of imported prawns used as bait and berley may be less because uncooked prawns with heads removed could be less popular with recreational fisherman. Finally, head-off prawns are unlikely to be fed to broodstock, and, therefore head removal may also reduce the likelihood of imported prawns are used for this purpose.

Use of prawns to feed broodstock, use of prawns as bait and berley and untreated waste disposal from the commercial processing of imported prawns were the three significant

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exposure pathways identified in Biosecurity Australia’s IRA. It is possible that the partial likelihood of exposure for the farmed, hatchery and wild groups is reduced if imported prawns had their head removed prior to entry. However, there is considerable uncertainty around the potential reduction. Therefore, the partial likelihood exposure of farmed, hatchery and crustacean broodstock was not altered from the unrestricted risk estimate for each of the pathogens.

Determination of the annual risk Head removal did not alter the partial annual likelihood of entry and exposure (PALEE) and as such there annual risk did not differ from the unrestricted risk estimates for each of the pathogens.

Conclusion Removal of the head did not reduce the risk associated with WSSV, IHHNV, YHV, NHPB and TSV below ALOP, and, therefore can not be considered as a suitable risk mitigation opinion.

10.2.2 Testing Biosecurity Australia’s IRA team considered testing of whole uncooked prawns for WSSV, YHV, NHPB, IHHNV and TSV by and concluded that

Given uncertainty about the sensitivity of available tests for prawn pathogens, this option alone is not expected to reduce the likelihood of entry and exposure sufficiently to reduce the overall risk to an acceptable level, but may be effective in combination with other measures.

While the authors of this report concur that there is uncertainty about the tests for prawn pathogens, the IRA team provided no evidence that this conclusion was reached in a systematic and transparent manner. Therefore, we have undertaken to evaluate testing as a risk mitigation strategy using the same framework that the IRA team used to complete the unrestricted risk estimates for each pathogen. Under a testing strategy each batch 4 of import uncooked whole prawns would be tested on arrival for WSSV, YHV, IHHNV, NHPB and TSV using the PCR molecular diagnostic tests5 at an AQIS approved laboratory. Batches with samples that tested positive would be destroyed.

Release assessment Testing for the presence of WSSV, YHV, IHHNV, TSY and NHPB will reduce the likelihood of release. However, as noted early in this report and by Biosecurity Australia’s IRA team, there is considerable uncertainty surrounding the sensitivity of tests used for prawn pathogens. Based on this uncertainty and the reported prevalence of pathogens in import prawn products the annual likelihood of release following testing would be reduced from high to low for WSSV, YHV, IHHNV, TSV and NHPB.

4 A batch is defined as a population from a different pond population or fishing period population. 5 PCR molecular diagnostic tests used are those recommended in the most current version of the OIE manual. Test may only differ from that described in the manual following appropriate validation in an AQIS approved laboratory.

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Exposure assessment The estimates for the partial likelihood of exposure for each of the exposure groups would be the same as those used in the unrestricted risk estimate.

Determination of the annual risk The partial annual risk for each group was determined by combining the partial likelihood of exposure and the consequences in each exposure group using the matrix rules provided in the Draft revision of the IRA for prawn and prawn product. Table 6 shows the results by pathogen. Application of the rules for combining partial annual risk found that the annual risk when uncooked whole prawns were tested and positive batches rejected is moderate for WSSV, YHV and IHHNV; low for NHPB; and negligible for TSV.

Conclusion Testing only reduced the risk associated with TSV below ALOP, and, therefore testing is not a suitable strategy for the control of the risk associated with WSSV, IHHNV, YHV and NHPB. Based on these results, current interim measures of testing uncooked whole prawns for WSSV does not reduce the risk associated with WSSV below ALOP. Furthermore, these interim measures do nothing to reduce the risk associated with IHHNV, YHV, and TSV. Thus, interim measures for the importation of uncooked whole prawns are inadequate.


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Table 6: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk if imported prawns are tested using PCR molecular diagnostic tests. Results presented stratified by exposure group and pathogenic agent.

Pathogenic agent Exposure group Variable WSSVa YHVb IHHNSc TSVd NHBPe

Farm LR Low Low Low Low Low PLE Low Low Low Low Low PALEE Very low Very low Very low Very low Very low Consequence High High High Low Moderate Partial annual risk Low Low Low Negligible Very low Hatchery LR Low Low Low Low Low PLE High High High Low High PALEE Low Low Low Low Low Consequence High High High Low Moderate Partial Risk Moderate Moderate Moderate Very low Low Wild LR Low Low Low Low Low PLE High Moderate Moderate Moderate Moderate PALEE Low Low Low Low Low Consequence Low Low Low Very low Low Partial Risk Very low Very low risk Very low Negligible Very low Combined Annual risk Moderate Moderate Moderate Very low Low

a White spot syndrome virus b Yellowhead virus c Infectious hypodermal and haematopoietic necrosis virus d Taura syndrome virus e Necrotising hepatopancreatitis bacterium


10.2.3 Licensing importer Licensing of importers is proposed as a risk mitigation strategy. Under this risk management options, importers of uncooked whole prawns would be required to hold a licence issued by an appropriate authority.

Release assessment Licensing of importers would prevent involvement of people who are unfamiliar with the industry and are more likely to import uncooked whole prawns that are contaminated with WSSV, YHV, IHHNV, TSV and NHPB. However this reduction is expected to be small, as this strategy does not include any requirement that the importer has a risk management plan in place. Therefore the annual likelihood of release for each of the pathogens would remain the same as the unrestricted risk estimates (i.e. the likelihood of release would be high).

Exposure assessment Licensed importers are not likely to influence the distribution of whole uncooked prawns and, as such, this risk management option would not alter the partial likelihood of exposure for the farm, hatchery or wild groups.

Determination of the annual risk Licensing of importers did not alter the partial annual likelihood of entry and exposure (PALEE) and as such the annual risk did not differ from the unrestricted risk estimates for each of the pathogens.

Conclusion Licensing of importers did not reduce the risk associated with WSSV, IHHNV, YHV, NHPB and TSV below ALOP, and, therefore can not be considered as a suitable risk mitigation opinion.

10.2.4 Defined market chain Risk associated with importation of uncooked whole prawns could be managed by the introduction of an audited risk management plan. Under an audited risk management plan the importers would be certified by an appropriate authority and must ensure that all imported product is:

Sourced from a farm that: - is free of WSSV, YHV, IHHNV, NHPB and TSV; - maintains a high level of biosecurity around the farm; and - has an active disease surveillance system.

Processed and packaged under conditions that minimise cross contamination.

Under this system the appropriate authority in Australia must:

Certify importers of uncooked whole prawns; Conduct regular spot audits of certified importers periodically to ensure the

integrity of the system. Importers should be obliged to inform the appropriate authorities if their imported product does not fulfil the above criteria for importation; and

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Conduct regular spot testing of imported product from certified importers to verify absence of disease.

Release assessment A defined market chain would ensure that imported product is sourced from disease free stocks. Furthermore, processing would ensure that there was no cross-contamination. Based on this information it is the authors’ opinion that importation of prawns with a defined market chain reduced the likelihood of release for WSSV, YHV, IHHNV, TSV and NHPB from high to extremely low.

Exposure assessment A defined market chain does not require certified importers to alter their distribution of whole uncooked prawns and, as such, this risk management options would not alter the partial likelihood of exposure for the farm, hatchery or wild groups.

Determination of the annual risk The likelihood of release was combined with the partial likelihood of exposure and the likely consequences in each exposure group to determine the partial risk using the matrix rule provided in the IRA. Table 7 shows the results by pathogen. Application of the rules for combining partial annual risk found that the annual risk when uncooked whole prawns were imported with a defined market chain was very low for WSSV, YHV and IHHNV and negligible for NHPB and TSV.

Conclusion The risk estimates for each of the five pathogens is below ALOP. Therefore, a defined market chain should be considered as a strategy to mitigate the risks associated with WSSV, IHHNV, YHV, NHPB and TSV. Suitable suppliers can be identified in at least some of the source countries.


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Table 7: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk if whole uncooked prawns were imported with a defined market chain. Results presented stratified by exposure group and pathogenic agent. Pathogenic Agent Exposure group Variable WSSVa IHHNVb YHVc TSVd NHPBe

Farm LR Extremely low Extremely low Extremely low Extremely low Extremely low PLE Low Low Low Low Low PALEE Extremely low Extremely low Extremely low Extremely low Extremely low Consequence High High High Low Moderate Partial Very low Very low Very low Negligible Negligible Hatchery LR Extremely low Extremely low Extremely low Extremely low Extremely low PLE High High High Low High PALEE Extremely low Extremely low Extremely low Extremely low Extremely low Consequence High High High Low Moderate Partial Risk Very low Very low Very low Negligible Negligible Wild LR Extremely low Extremely low Extremely low Extremely low Extremely low PLE High Moderate Moderate Moderate Moderate PALEE Extremely low Extremely low Extremely low Extremely low Extremely low Consequence Low Low Low Very low Low Partial Risk Negligible Negligible Negligible Negligible Negligible All Annual risk Very low Very low Very low Negligible Negligible



10.2.5 Regulation of the bait industry and recreational fishing The risk associated with the importation of uncooked whole prawns could be mitigated by regulating the bait industry. Regulation of the bait industry would ensure that all prawns sold in bait shops were either Australia farmed prawns or wild caught. To assist with compliance, imported uncooked whole prawns would:

• only be available for sale in one kilogram bags

• be labelled ‘for human consumption only’ and/or ‘unsuitable for bait’; and

• be greater than 15 g.

There would also be a campaign to educate the public about the dangers of using imported prawns as bait and berley. Gamma irradiation of all prawns to be sold as bait would be effective in eliminating infectivity from the material, if this was considered feasible.

To further reduce the risk to farmed prawns, new regulations would need to be implemented to ban fishing within 200 metres of an inlet pipe to a prawn farm. It is also recommended that all water intake pipes to prawn farms have a screen with 120 micron fine mesh. This would prevent solid material (e.g. prawns used as bait) that may harbour exotic pathogens from entering the farm. Most farms already filter water intake, and this could be enhanced through regulation or an industry code of practice. The advantage of these measures is that they not only reduce the risk of exposure to exotic pathogens, but will also reduce the likelihood of introduction of endemic prawn diseases to the farm from wild prawns. Release assessment Regulation of the bait industry and recreational fishing in the vicinity of prawn farms would not impact on the likelihood of release. Therefore, the likelihood of release for WSSV, YHV, IHHNV, TSV, and NHPB would be high.

Exposure assessment Biosecurity Australia’s IRA team identified the use of imported prawns for bait and berley as a significant exposure pathway for both wild and farmed crustaceans. Presently, imported prawns are only intended for human consumption but there is a real possibility that they could be diverted to bait retailers. Regulation of the bait industry coupled with labelling of products and education of staff in wholesale operations would substantially reduce the likelihood of this occurring. Be that as it may, a small but significant number of recreational fisherman purchase prawns intended for human consumption from seafood outlets. Estimates by Biosecurity Australia’s IRA team suggest that between 35 and 117 tonnes, or less than one percent6, of prawns purchased from seafood outlets were used for bait or berley. Size minimums on imported prawns, labelling and public education campaigns could be expected to reduce the likelihood of imported prawns being used for bait or berley. However, it would not be reasonable to expect these measures to completely prevent imported uncooked whole prawns being used for bait or berley. Given the issues with compliance, the partial likelihood of exposure in the wild group was considered to be low and the partial likelihood of exposure in farmed prawns was reduced to very low.

6 Based on estimates of prawn sales in 2002-03 and 2004-05 presented in Biosecurity Australia IRA for prawn and prawn products.

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Use of imported prawns as bait or berley was not identified as exposure pathway for hatchery crustaceans. Therefore, the partial likelihood of exposure in this group for each pathogen was not altered from the unrestricted risk estimate (i.e. the partial likelihood of exposure was high for WSSV, YHV, IHHNV and NHBP and low for TSV).

Determination of the annual risk For each pathogen the partial annual risk for each group was determined by combining the partial likelihood of exposure in this report with the likelihood of release and consequences in each exposure group using the matrix rules provided in the Draft revision of the IRA for prawn and prawn product. Table 8 shows the results by pathogen. The annual risk when uncooked whole prawns were imported without restriction and there was regulation of the bait industry and recreational fisherman is high for WSSV, YHV and IHHNV; moderate for NHPB; and very low for TSV.

Conclusion Despite significant reductions in the partial annual risk for farmed and wild crustaceans only the risk associated with TSV is below ALOP. Therefore, regulation of bait industry and a ban on recreational fishing within the vicinity of prawn farms is not a suitable option to manage the risk associated with WSSV, YHV, IHHNV, and NHPB. However, it could be used in conjunction with options that lower the partial risk in the hatchery exposure group.


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Table 8: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when there is regulation of the bait industry and a ban on recreational fishing in the vicinity of prawn farms. Results stratified by exposure group and pathogenic agent.

Pathogenic Agent Exposure group Variable WSSVa IHHNVb YHVc TSVd NPHBe

Farm LR High High High High High PLE Very low Very low Very low Very low Very low PALEE Very low Very low Very low Very low Very low Consequence High High High Low Moderate Partial Risk Low Low Low Negligible Very low Hatchery LR High High High High High PLE High High High Low High PALEE High High High Low High Consequence High High High Low Moderate Partial Risk High High High Very low Moderate Wild LR High High High High High PLE Low Low Low Low Low PALEE Low Low Low Low Low Consequence Low Low Low Very low Low Partial Risk Very low Very low Very low Negligible Very low All Annual risk High High High Very low Moderate



10.2.6 Regulation of feeding practices on prawn farms and hatcheries Hatchery broodstock cannot be sustained on dry feed alone, they have a requirement for fresh feed including fish, squid and prawns. Prawns are currently only used as feed by a minority of the prawn hatcheries. Not only do fresh prawns as a feed source to prawns present a risk of exposure to exotic pathogens, they will also increase the likelihood of disease spread of pathogens already present and the emergence of new diseases. In short, it is bad practice. There is, therefore, a strong argument to mitigate the exposure of hatchery broodstock through a ban on the use of prawns as feed, not only to minimise the risk of exotic disease establishment but also to improve biosecurity more generally. Only 14 hatcheries are currently operating in Australia. Thus enforcement of a ban on prawn feeding is not logistically demanding. It is understood that such a ban would be supported by the prawn farming industry. The regulation could be further strengthened though a ban on the sale of prawns as feed for prawns. Regulation of the industry would be coupled with an education program advising farmers of the disease risk associated with feeding prawn products to farms, labelling imported uncooked whole prawns for ‘human consumption only’ and packaging uncooked whole prawns in one kilogram packages.

Release assessment Regulation of feeding practices would not impact on the likelihood of release. Therefore, the likelihood of release for WSSV, YHV, IHHNV, TSV, and NHPB would remain high.

Exposure assessment The use of feed to condition broodstock was the only significant exposure pathway for hatchery stock identified by Biosecurity Australia’s IRA team. Thus, prohibiting the feeding of prawns to broodstock would remove the opportunity for hatchery stock to be exposed to prawn pathogens. Given that are only fourteen hatcheries in Australia, and feeding of prawns is not considered ‘appropriate practice’ it would reasonable to expect good compliance with the regulation. Therefore, the partial likelihood of exposure in the hatchery group would be reduced from high to extremely low for WSSV, YHV, IHHNV and NHIBP and from low to negligible for TSV.

The use of feed to condition broodstock was one of two significant exposure pathways for farmed crustaceans. Therefore, prohibiting the feeding of prawns to broodstock will not totally remove the opportunity for exposure in farmed crustaceans. This notwithstanding, for each of the pathogens, it would be reasonable to expected a reduction in the partial likelihood of entry for farmed crustaceans from low to very low.

The IRA team did not consider the use of imported prawns as feed to condition broodstock as a significant exposure pathway for wild crustaceans. Consequently, for each of the pathogens the partial likelihood of exposure in the wild crustaceans was not altered from that selected by the IRA team when completing their unrestricted risk estimates.

Determination of the annual risk For each pathogen the partial annual risk for each group was determined by combining the partial likelihood of exposure in this report with the likelihood of release and consequences in each exposure group using the matrix rules provided in the Draft revision of the IRA for prawn and prawn product. Table 9 shows the results by pathogen. The annual risk when

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there was regulation of feeding practices in hatcheries and prawn farms was low for WSSV, YHV, IHHNV; and NHPB; and very low for TSV.

Conclusion Despite significant reductions in the partial annual risk for hatchery and farmed crustaceans only the risk associated with TSV was below ALOP. Therefore, regulation of feeding practices in hatcheries and prawn farms is not a suitable option to manage the risk associated with WSSV, YHV, IHHNV, and NHPB. However, it could be used in conjunction with options that lower the partial risk in the wild exposure group.


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Table 9: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk associated with importation of uncooked whole prawns when there is regulation of feeding practices in prawn farms and hatcheries. Results presented stratified by exposure group and pathogenic agent

Pathogenic agent Exposure group Variable WSSVa IHHNVb YHVc TSVd NHPBHe

Farm LR High High High High High PLE Very low Very low Very low Very low Very low PALEE Very low Very low Very low Very low Very low Consequence High High High Low Moderate Partial Risk Low Low Low Negligible Very low Hatchery LR High High High High High PLE Extremely low Extremely low Extremely low Negligible Extremely low PALEE Extremely low Extremely low Extremely low Negligible Extremely low Consequence High High High Low Moderate Partial Risk Very low Very low Very low Negligible Negligible Wild LR High High High High High PLE High Moderate Moderate Moderate Moderate PALEE High Moderate Moderate Moderate Moderate Consequence Low Low Low Very low Low Partial Risk Low Low Low Very low Low All Annual risk Low Low Low Very low Low



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10.2.7 Commercial processing of imported uncooked whole prawns in AQIS approved facilities

Under this option whole uncooked prawns could only be processed on-shore in Australia under quarantine control, where all waste is treated as quarantinable. Processing in these facilities could include, but it not limited to, removal of the head, removal of the head and shell, coating, marinating and crumbing. Disposal of solid and liquid waste from the processing would be required to be undertaken in a bio-safe manner which eliminated infection.

Release assessment Regulation of commercial processing of imported prawns will not impact on the likelihood of release. Therefore, the likelihood of release for WSSV, YHV, IHHNV, TSV, and NHPB would high.

Exposure assessment Biosecurity Australia’s IRA team identified disposal of untreated solid and liquid waste from the commercial processing of imported prawns as one of two significant exposure pathways for the wild crustacean group. Consequently, limiting processing on the whole uncooked prawns would reduce the partial likelihood of exposure in this group. However, there is still opportunity for exposure in this group via the use of imported uncooked whole prawns as bait or berley. Following consideration of these issues, the partial likelihood of exposure in the wild crustaceans was reduced to low for each of the five pathogens.

According to the IRA team, untreated liquid and solid waste from commercial processing imported prawns is not a significant exposure pathway for either the farmed or hatchery crustacean groups. Therefore, for each of the pathogens the likelihood of exposure was not changed from that used in the unrestricted risk estimate completed by Biosecurity Australia.

Determination of the annual risk For each pathogen the partial annual risk for each group was determined by combining the partial likelihood of exposure in this report with the likelihood of release and consequences in each exposure group using the matrix rules provided in the Draft revision of the IRA for prawn and prawn product. Table 10 shows the results by pathogen. The annual risk when uncooked whole prawns were imported without restriction and there was regulation of the commercial processing was high for WSSV, YHV and IHHNV; moderate for NHPB; and low for TSV.

Conclusion Despite reductions in the partial risk in the wild crustacean group the risk associated with WSSV, YHV, IHHNV, NHPB and TSV exceed ALOP. Therefore limiting commercial processing of imported uncooked whole prawns to AQIS approved facilities is not a suitable risk mitigation strategy. However, it could be used in conjunction with other measures that reduce the partial risk in the hatchery and farm crustacean groups.


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Table 10: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when commercial processing of imported uncooked whole prawns is undertaken in AQIS approved facilities. Results presented stratified by exposure group and pathogenic agent.

Pathogenic Agent Exposure group

Variable WSSVa IHHNVb YHVc TSVd NHPBHe

Farm LR High High High High High PLE Low Low Low Low Low PALEE Low Low Low Low Low Consequence High High High Low Moderate Partial Risk Moderate Moderate Moderate Very low Low Hatchery LR High High High High High PLE High High High Low High PALEE High High High Low High Consequence High High High Low Moderate Partial Risk High High High Very low Moderate Wild LR High High High High High PLE Low Low Low Low Low PALEE Low Low Low Low Low Consequence Consequence Low Low Low Very low Low Partial Risk Very low Very low Very low Negligible Very low All Annual risk High High High Very low Moderate



10.2.8 Market limitations There are only 24 prawn farms and 14 hatcheries in Australia. As a result, the risk associated with the importation of uncooked whole prawns could be managed by restricting the sale of imported prawns around prawn farms and hatcheries. Under this strategy importers of uncooked whole prawns would have to be certified by the appropriate authority. In addition to certifying importers of uncooked whole prawns, the appropriate authority in Australia must conduct regular spot audits of certified importer to ensure the integrity of the system. Importers should be obliged to inform the appropriate authorities if imported product has been distributed in a restricted area.

Market limitation is possible under Article 6 of the SPS agreement that allows importing countries to adapt risk mitigation strategies to the area from which the product originates or to which it is destined. Article 6 has been used by Australian authorities to restrict the sale of New Zealand apples in Western Australia. The sale of imported salmon has also be been banned in Tasmania. However, this restriction was imposed by the state government and its compatibility with international trade law is unresolved.

Release assessment Market limitation of imported prawns will not impact on the likelihood of release. Therefore, the likelihood of release for WSSV, YHV, IHHNV, TSV, and NHPB would be high.

Exposure assessment Market limitation would reduce the volume of imported uncooked whole prawns around prawn farms and hatcheries. It would be reasonable to expect that limiting sale in retail outlets would reduce the likelihood that imported prawns would be used as feed to condition broodstock or as bait and berley by recreational fishermen in these regions.

For farmed crustaceans, the significant exposure pathways identified by Biosecurity Australia’s IRA team were the use of imported prawns as feed to condition broodstock and the use of imported prawns for bait or berley by recreational fisherman. Market limitation would reduce the likelihood of exposure via both these pathways. However, it is still possible that recreational fisherman would buy imported prawns from an area outside of the restricted sale area, and, therefore, market limitation may still allow imported prawns to be used rarely for bait or berley in the vicinity of farmed prawns. Consequently, the partial likelihood of exposure in the farmed group is estimated to be very low.

The only significant exposure pathway for hatchery crustaceans identified by Biosecurity Australia’s IRA team was feeding imported prawns to condition broodstock. Market limitation could be expected to reduce the likelihood that imported prawns are fed in this way as retailers in the restricted area would not sell imported prawns. Hatcheries could conceivably buy prawns for feed outside the restricted areas, and therefore the partial likelihood of exposure in the hatchery group was reduced from high for WSSV, YHV, IHHNV and NHPB to low and from low to extremely low for TSV.

Market limitation would only be operational in areas with prawn farms or hatcheries and as such would do little to reduce the likelihood that imported prawns would be used for bait or berley in areas with wild stocks of crustaceans. Thus, market limitation would not reduce the partial likelihood of exposure in the wild group.

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Determination of the annual risk The partial likelihood of release was combined with the likelihood of release and the likely consequences in each exposure group to determine the partial risk using the matrix rule provided in the Draft revision of the IRA for prawn and prawn product. Table 11 shows the results by pathogen. Application of the rules for combining partial annual risk found that the annual risk when there was market limitations on the sale of imported uncooked whole prawns is moderate for WSSV, YHV and IHHNV; low for NHPB; and very low for TSV.

Conclusion Despite reducing the partial risk in the hatchery and farmed groups, market limitation reduces only the risk associated with TSV virus below ALOP. Therefore, market limitation alone is not a suitable strategy to mitigate the risk associated with WSSV, IHHNV, YHV and NHPB.


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Table 11: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when there is market limitation on the sale of imported uncooked whole prawns. Results presented stratified by exposure group and pathogenic agent.

Pathogenic Agent Exposure group

Variable WSSVa IHHNVb YHVc TSVd NHPBHe

Farm LR High High High High High PLE Very low Very low Very low Very low Very low PALEE Very low Very low Very low Very low Very low Consequence High High High Low Moderate Partial Risk Low Low Low Negligible Very low Hatchery LR High High High High High PLE Low Low Low Extremely low Low PALEE Low Low Low Extremely low Low Consequence High High High Low Moderate Partial Risk Moderate Moderate Moderate Negligible Low Wild LR High High High High High PLE High Moderate Moderate Moderate Moderate PALEE High Moderate Moderate Moderate Moderate Consequence Low Low Low Very low Low Partial Risk Low Low Low Very low Low All Annual risk Moderate Moderate Moderate Very low Very low



10.3 Combination of risk management options

10.3.1 Regulation of bait industry, recreational fishing and feeding practices on prawn farms and hatcheries

Analysis present earlier in this report showed that:

• regulation of the bait industry, a ban on recreational fishing in the vicinity of prawn farms and installation of a filter on all water inlets to prawn farms and hatcheries significantly reduced the partial annual risk for the wild and farm crustacean exposure groups; and

• regulation of feeding practices on prawn farms and hatcheries would greatly reduce the partial risk for the hatchery and farmed crustacean exposure groups.

Consequently, the combined effects of these two strategies should be considered as an option to mitigate the disease risk associated with the importation of uncooked whole prawns.

Release assessment Regulation of the bait industry, recreational fishing and feeding practices on prawn farms would not impact on the likelihood of release. Therefore, the likelihood of release for WSSV, YHV, IHHNV, TSV, and NHPB would high.

Exposure assessment Biosecurity Australia’s IRA team identified the significant exposure pathways for farmed crustaceans as use of imported prawns for bait or berley and use of imported prawns as feed to condition broodstock. Therefore, regulation of the bait industry, a ban on recreational fishing near prawn farms and regulation of feeding practices would remove the opportunity for exposure, making the likelihood of exposure in farmed prawn negligible. However, there is a real risk of non-compliance with the regulation and as such the partial likelihood in this group was reduced from low to extremely low.

The use of prawns as feed to condition broodstock was the only significant exposure pathway for hatchery stock identified by Biosecurity Australia’s IRA team. For reasons described in the previous section the partial likelihood of exposure in the hatchery group would be reduced from high to extremely low for WSSV, YHV, IHHNV and NHIBP and from low to negligible for TSV.

Biosecurity Australia’s IRA team identified the use of imported prawns as bait and berley as one of two significant exposure pathways for wild crustaceans. For reasons described in an earlier section the partial likelihood of exposure in the wild group was considered to be low for each of the five pathogens.

Determination of the annual risk For each pathogen the partial annual risk for each group was determined by combining the partial likelihood of exposure in this report with the likelihood of release and consequences in each exposure group using the matrix rules provided in the Draft revision of the IRA for prawn and prawn product. Table 12 shows the results by pathogen. The annual risk when there was regulation of the bait industry, fishing practices and feeding practices is low for WSSV, YHV and IHHNV; very low for and NHPB; and negligible for TSV.

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Conclusion The restricted risk when regulation of the bait industry, fishing practices and feeding practices exceeds ALOP for WSSV, YHV and IHHNV, and therefore can not considered a suitable risk management strategy for the risk associated with these pathogens. In contrast, the restricted risk for NHPH and TSV was below ALOP indicating that these measures could be used to mitigate the risks associated with the NHPH and TSV.


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Table 12: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk when these is regulation of the bait industry, a ban on recreational fishing in the vicinity of prawn farms and regulation feeding practices on prawn and hatcheries. Results presented stratified by exposure group and pathogenic agent

Pathogenic Agent Exposure group Variable WSSVa IHHNVb YHVc TSVd NHPBe

Farm LR High High High High High PLE Extremely low Extremely low Extremely low Extremely low Extremely low PALEE Extremely low Extremely low Extremely low Extremely low Extremely low Consequence High High High Low Moderate Partial Risk Very low Very low Very low Negligible Negligible Hatchery LR High High High High High PLE Extremely low Extremely low Extremely low Negligible Extremely low PALEE Extremely low Extremely low Extremely low Negligible Extremely low Consequence High High High Low Moderate Partial Risk Very low Very low Very low Negligible Negligible Wild LR High High High High High PLE Low Low Low Low Low PALEE Low Low Low Low Low Consequence Low Low Low Very low Low Partial Risk Very low Very low Very low Very low Very low All Annual risk Low Low Low Very low Very low



10.3.2 Regulation of bait industry, recreational fishing, feeding practices on prawn farms and hatcheries and commercial processing

Analysis present earlier in this report showed that:

• regulation of the bait industry and a ban on recreational fishing in the vicinity of prawn farms significantly reduced the partial annual risk for the wild and farm crustacean exposure groups;

• regulation of feeding practices on prawn farms and hatcheries would greatly reduce the partial risk for the hatchery and farmed crustacean exposure groups; and

• limiting commercial processing of imported uncooked whole prawns in AQIS approved facilities reduced the partial likelihood of exposure in wild stock.

Consequently, the combined effects of these three strategies should be considered to mitigate the disease risk associated with the importation of uncooked whole prawns.

Release assessment Regulation of the bait industry, recreational fishing, commercial processing and feeding practices on prawn farms and hatcheries would not impact on the likelihood of release. Therefore, the likelihood of release for WSSV, YHV, IHHNV, TSV, and NHPB would be high.

Exposure assessment Biosecurity Australia’s IRA team identified the significant exposure pathways for farmed crustaceans as use of imported prawns as bait or berley and as feed to condition broodstock. Therefore, regulation of the bait industry, recreational fishing and feeding practices would remove the opportunity for exposure, making the likelihood of exposure in farmed prawn negligible. However, there is a real risk of non-compliance with the regulation and as such the partial likelihood of exposure in the farmed group was reduced from low in the unrestricted risk estimate to extremely low.

The use of feed to condition broodstock was the only significant exposure pathway for hatchery stock identified by Biosecurity Australia’s IRA team. For reasons described in the previous section the partial likelihood of exposure in the hatchery group would be reduced from high to extremely low for WSSV, YHV, IHHNV and NHIBP and from low to negligible for TSV.

Biosecurity Australia’s IRA team identified the use of imported prawns as bait and berley and untreated commercial waste as the two significant pathways. Therefore, the combination of regulations proposed would effectively remove the potential exposure pathways. However, there is a real risk of non-compliance with the regulation of the bait industry and as such the partial likelihood of exposure in the wild group was only reduced to very low.

Determination of the annual risk For each pathogen the partial annual risk for each group was determined by combining the partial likelihood of exposure in this report with the likelihood of release and consequences in each exposure group using the matrix rules provided in the Draft revision of the IRA for prawn and prawn product. Table 13 shows the results by pathogen. The annual risk when there was regulation of the bait industry, fishing practices and feeding practices was low for WSSV, YHV and IHHNV; very low for and NHPB; and negligible for TSV.

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Conclusion The risk estimates for each of the five pathogens is below ALOP. Therefore, regulation of the bait industry, a ban on recreational fishing in the vicinity of prawn farms, requirement for a filter on water intakes of prawn farms, regulation of feeding practices in prawn farms and hatcheries and limiting commercial processing to AQIS approved facilities is effective as a strategy to mitigate the risks associated with WSSV, IHHNV, YHV, NHPB and TSV. It is noteworthy that the measures listed here which would take time to implement were stated in Biosecurity Policy Memorandum 2001/06 to be about to be implemented, while the remaining measures could be implemented quickly. Therefore this risk management strategy is clearly feasible, if there is a commitment to implement it as part of an integrated national risk management program for prawn diseases.


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Table 13: Likelihood of release (LR), partial likelihood of exposure (PLE), partial annual likelihood of entry and exposure (PALEE), likely consequence and partial annual risk associated when there is regulation of the bait industry, ban on recreational fishing in the vicinity of prawn farms, regulation of feeding practices in prawn and hatcheries and limiting commercial processing of imported uncooked whole prawns to AQIS approved facilities. Results presented stratified by exposure group and pathogenic agent.

Pathogenic Agent

Exposure group Variable WSSVa IHHNVb YHVc TSVd NHPBe

Farm LR High High High High High PLE Extremely low Extremely low Extremely low Extremely low Extremely low PALEE Extremely low Extremely low Extremely low Extremely low Extremely low Consequence High High High Low Moderate Partial Risk Very low Very low Very low Negligible Negligible Hatchery LR High High High High High PLE Extremely low Extremely low Extremely low Extremely low Extremely low PALEE Extremely low Extremely low Extremely low Extremely low Extremely low Consequence High High High Low Moderate Partial Risk Very low Very low Very low Negligible Negligible Wild LR High High High High High PLE Very low Very low Very low Very low Very low PALEE Very low Very low Very low Very low Very low Consequence Low Low Low Very low Low Partial Risk Negligible Negligible Negligible Negligible Negligible All Annual risk Very low Very low Very low Negligible Negligible



10.4 Sensitivity analysis for risk management options recommended in the IRA report

10.4.1 Cooking The IRA estimated that cooking would reduce the PLEE for WSSV and YHV to at least extremely low for each of the exposure groups. If the estimate for PLEE in either the farmed or hatchery group was increased to very low, then the annual risk would increase to low, and, therefore exceed ALOP. In contrast, the PLEE associated with WSSV or YHV for the wild crustacean group could increase to low before the annual risk associated with WSSV or YHV would exceed ALOP (i.e. very low).

The IRA estimated that cooking would decrease PLEE associated with NHPB to negligible for each of the exposure groups. Given that the ‘likely consequence’ in the farmed and hatchery groups was estimated to be low, if the PLEE in either of these groups increased to low then the annual risk associated with NHPB would increase to low, and, therefore exceed ALOP. The ‘likely consequences’ associated with NHBP in the wild exposure group was very low, and, therefore the PLEE associated with this agent could increase to moderate before the annual risk would exceed ALOP.

Cooking was estimated to reduce the PLEE associated with TSV to at least very low. The likely consequences of TSV in the farm and hatchery exposure groups is low; therefore the PLEE associated with TSV in either of these exposure groups could be increased to moderate before the annual risk would increase to low (and therefore exceed ALOP). In contrast, in the wild group the PLEE associated with TSV could increase to high without the annual risk exceeding ALOP.

Sensitivity analysis was not conducted for cooking as a risk mitigation option for IHHNV because the estimated value for PLEE resulted in an annual risk that was above ALOP. As noted in a previous section this is no doubt an oversight.

10.4.2 Processing High level of processing was estimated to reduce the PLEE associated with WSSV, IHHNV, YHV, NHPB, and TSV to negligible in the farm and hatchery exposure groups and to very low in the wild crustacean group.

If the estimate for PLEE associated with WSSV, IHHNV, and YHV in either the farmed or hatchery group increased two levels on the qualitative scale to very low then the annual risk would increase to low, and, therefore exceed ALOP. In contrast, the PLEE for the wild crustacean group would only need to increase one level on the qualitative scale to low before the annual risk would exceed ALOP.

The IRA estimated that the ‘likely consequences’ associated with NHPB were moderate for the farmed and hatchery groups and low for the wild group. Therefore, the PLEE in these groups would need to increase to low before the annual risk would increase to low, and, therefore exceed the ALOP. Similarly, the PLEE associated with NHPB would need to increase from very low to moderate before the annual risk would exceed ALOP.

The ‘likely consequences’ associated with TSV were low for the farmed and hatchery groups and very low for the wild group. Thus the PLEE in either the farm or hatchery groups would need to increase to moderate before the annual risk increased above very

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low. Increasing the PLEE in the wild group would still not increase the partial risk above very low, and as such the combined risk would not exceed ALOP.

10.4.3 Head and shell removal The IRA reported the partial likelihood of entry and exposure with head and shell removal only for TSV and NHPB. The IRA estimated that head and shell removal was expected to reduce the PLEE for both pathogenic agents to very low for the farm and hatchery exposure groups and at least low for the wild crustaceans.

If the PLEE for NHPB in either the farm and hatchery groups increased by one level on the qualitative scale from very low to low then the annual risk associated with the pathogen would increase to low, and as such exceed Australia’s ALOP. Similarly, if the PLEE for wild increased one level on the qualitative scale from low to moderate then annual risk would be also be low, thus exceeding ALOP.

The ‘likely consequences’ in each exposure group were different for TSV, thus the PLEE for either the farm or hatchery exposure group could increase two levels on the qualitative scale to moderate before the annual risk would exceed Australia’s ALOP. Given that the ‘likely consequences’ in the wild group was estimated to be ‘very low’ increasing the PLEE in the wild group would still not increase the partial risk above very low, and as such the combined risk would not exceed ALOP.

10.4.4 Testing and head and shell removal The IRA estimated that testing in combination with head and shell removal would decrease the PLEE associated with WSSV, IHHNV, YHV, NHPB, and TSV to extremely low in the farm and hatchery exposure groups and very low in the wild groups. Given that the ‘likely consequences’ for each of these agents is ‘high’ for both the farm and hatchery groups if the PLEE in either of these groups increased one level of the qualitative scale to very low the annual risk would increase to low, thus exceeding Australia’s ALOP. Given that the ‘likely consequence’ in the wild group was low for each of these pathogens, the PLEE for the wild exposure group could increase from very low to moderate before the annual risk would exceed ALOP.

10.4.5 Other risk management options The IRA considered a number of other risk management options but determined that they would not reduce the risk for any of the pathogenic agents below ALOP. These were:

• Minimum size;

• Labelling for human consumptions;

• Post-harvest inspection to ensure absence of clinical signs of disease;

• Sourcing from wild stock; and

• Sourcing from non-emergency harvested stock.

However, the authors of the report did not provide estimates of the partial likelihood of entry and exposure, likelihood of release or the partial likelihood of exposure. It was, therefore, impossible to evaluate the rationale underlying their conclusions, or to complete a sensitivity analysis for any of the options considered by the IRA team as not

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reducing the annual risk to ALOP. Therefore, the IRA report clearly fails the criterion of transparency once again.

10.5 Sensitivity analysis-risk management strategies proposed in this report

10.5.1 Combination option Regulation of the bait industry, a ban on recreational fishing in the vicinity of prawn farms, use of filters on prawn farm water intakes, regulation of feeding practices in prawn farms and hatcheries and limiting commercial processing to AQIS approved facilities decreased the PLEE associated with WSSV, IHHNV, YHV, NHPB and TSV to extremely low for the farm and hatchery groups and very low in the wild group. Consideration of the ‘likely consequences’ in the farm and hatchery exposure groups for WSSV, IHHNV and YHV shows that the PLEE associated with these agents could increase one level on the qualitative level to very low before the annual risk would exceed ALOP. While, the PLEE associated with NHPB in farm and hatchery groups could increase to low before the annual risk exceed ALOP. Similarly, the PLEE associated with TSV could increase from extremely low to moderate before the annual risk would increase to at least low, and, thus exceed ALOP. For each of the five agents the ‘likely consequences’ in the wild exposure group was low for WSSV, IHHNV, YHV and NHPB and very low for TSV. Therefore, the PLEE associated with WSSV, IHHNV, YHV and NHPB in the wild group could increase from very low to moderate before the annual risk would exceed ALOP. In contrast, the PLEE associated with TSV could be high and the annual risk would remain below ALOP.

10.5.2 Defined market chain A defined market chain reduced the annual risk for the five pathogenic agents below ALOP because it was determined that this option reduces the likelihood of release to extremely low. If likelihood of release for each of the pathogenic agents only decreased to very low, the annual risk would be low for WSSV, YHV and IHHV, very low for NHBP and negligible for TSV. Therefore, the risk would be acceptable for NHBP and TSV but would exceed ALOP for WSSV, YHV, and IHHV. If the likelihood of release for each of the agents only decreased to low, then annual risk would exceed ALOP for all but TSV.

It is noteworthy that the risk management strategies we have identified (i.e. combination of post-border controls and defined market chain) have ‘safety margins’7 equivalent to some of the risk management strategies (e.g. cooking and testing with head and shell removal) identified in the Draft IRA as acceptable.

10.6 Recommendations The only two risk management options for whole uncooked prawns that were found to reliably reduce the level of risk to below ALOP for all five pathogenic agents are:

• A defined market chain; and • Regulation of the bait industry, a ban on recreational fishing in the vicinity

of prawn farms, screening of water intakes on prawn farms and hatcheries, regulation of feeding practices on prawn farms and hatcheries and limiting

7 Safety margin can be defined as the difference between ALOP and the restricted annual risk

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commercial processing of imported uncooked prawns to AQIS approved facilities.

These options were not considered in the IRA conducted by Biosecurity Australia.

10.7 Compliance with the Sanitary and Phytosanitary Agreement

10.7.1 Proposed risk management methods Measures proposed in the IRA are not the least trade restrictive available, as shown in this report. The analytical procedures and data used are not transparent, and it is not possible to be sure what was done in some parts of the analysis. The analytical procedure fails to comply with the OIE Aquatic Animal Health Code. Therefore the IRA and its conclusions do not comply with the SPS Agreement in multiple respects.

10.7.2 Implementation of changes in current interim measures The proposal in the IRA to implement new risk management measures shortly after the end of this consultation period is in breach of Article 5 of the SPS Agreement and Clause 2 of Annex B, since no case has been made that there is an urgent need to implement new measures, and the proposed changes would be very disruptive to trade, including trade with developing countries.

11: Conclusion The draft IRA contains serious structural and analytical problems which mean that it does not comply with the Biosecurity Australia Import risk analysis handbook and it does not meet either WTO or OIE requirements for a risk analysis. Therefore the Executive Manager of Biosecurity Australia is unable to recommend modifications to Australian import policy based on the IRA in its present form. When an analysis is conducted using the same framework but adjusted likelihood values, the only product for which risk management measures are required is whole raw prawns (including head-off shell-on prawns). Other products fall below ALOP and should be imported without restriction. For whole raw prawns (including head-on shell-off prawns), two risk management strategies are identified which will reliably meet ALOP, and could be implemented. In contrast, the risk management strategy proposed in the IRA does not satisfy SPS requirements and is unacceptable. There is no justification for implementing additional interim risk management measures beyond those which have been in place for six years, and the IRA process should be completed before any further action is taken. Any immediate action would contravene the SPS Agreement.

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Appendix 1. Summary of species susceptibility to the identified hazards

Experimental evidence Hazard Host (name)

cohabit Per os Parenteral1

Natural infections2

Freshwater prawns √ √ √ √

Marine prawns (Litopenaeus vannamei,...)

√ √ √ √

Crabs (Callinectes arcuatus) ? ? ? √

Crayfish(Procambarus spp. and Orconectes punctimanus)

√ √

Polychaete worms (Marphysa gravel) √

Lobsters ? ? ?

WSSV

Rotifer eggs (as reservoir) ? ? ? √

Panaeids:

Farfantepenaeus aztecus √

Farfantepenaeus duorarum √

Marsupenaeus japonicus √

Fenerropenaeus merguiensis √ √

Panaeus monodon √ √ √

Litopenaeus stylirostris √ √

Litopenaeus setiferus √ √

Litopenaeus vannamei √

Other Prawn species:

Metapanaeus ensis √

Euphasia superha √

Macrobrachium rosenbergii √

Acetes sp. √

Palaemon styliferus √

Other crustacean species

Sesarma sp. √

Uca spina √

Scylla serrata √

YHV

Portunus pelagicus √

Litopenaeus stylirostris √

Litopenaeus setiferus √

Litopenaeus vannamei √ √

Panaeus monodon X √ √

Metapanaeus ensis √ √

Taura SV

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Experimental evidence



Fenerropenaeus merguiensis X √

Fenerropenaeus chinensis √

Palaemon styliferus √

Metapanaeus monoceros √

Litopenaeus schmitti √

Freshwater prawns (Macrobrachium sp.)

√

Krill (Acetes sp.) √

Crabs (Sesarma sp. & Scylla serrata) √


Litopenaeus vannamei √

Panaeus monodon √




Farfantepenaeus californiensis √ √

Litopenaeus setiferus √

Litopenaeus occidentalis √

Panaeus semisulcatus √

IHHNV

Fenerropenaeus chinensis √


Litopenaeus vannamei √ √

Litopenaeus setiferus √ √


NHPB

Farfantepenaeus californiensis √

√ = successful transmission X = unsuccessful transmission ? = uncertain

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peer review of the biosecurity australia’s revised draft …€¦ · · 2014-08-08prawns and...

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