Biosecurity within the Australian Prawn Industry

1. Biosecurity within the Australian Prawn Industry Dr Matt Landos1BVSc(HonsI)MANZCVS Future Fisheries Veterinary Service Pty Ltd Prawn Superpowers Summit 31 July 2012, QLD

2. What is Biosecurity at National level? • A strategic management approach using both policy and regulatory frameworks • Biosecurity is aimed at analyzing and managing the various RISKS to the sectors dealing with: Food Safety Animal life (and health) Plant life (and health) The environment Prawn Superpowers Summit 31 July 2012, QLD

3. What is Biosecurity at prawn farm level? • The aim is prevention of introduction and spread of organisms or disease agents, as eradication or treatment is often not an option. • “An ounce of prevention is worth a pound of cure” Prawn Superpowers Summit 31 July 2012, QLD

4. Why is Biosecurity important ? Better tools for detection/ management of hazards Increasing human population Focus on biosecurity Increasing volume/ diversity of trade Increased public health demands Changing climate/ agricultural practice Greater need for environmental protection Prawn Superpowers Summit 31 July 2012, QLD

5. Why bother with biosecurity? • Direct financial loss to farms (WSSV>$1billion) • Loss of employment • Disruption of industry • Threat to food safety • Potential environmental harm • Pollution • Trading restrictions affecting markets and future trade Prawn Superpowers Summit 31 July 2012, QLD

6. Global climate of free trade Prawn Superpowers Summit 31 July 2012, QLD

7. Exotic disease outbreaks can be severe ~70% of Australia’s wild sardine biomass died from exotic herpesvirus outbreak Photo courtesy WA Fisheries

8. What elements are in a farm biosecurity plan? • Development of Standard Operating Procedures (SOPs) • Pre-transport certification (broodstock) • Quarantine (broodstock) sanitation measures on effluent • Surveillance (PL’s and growing stock) • Contingency planning for the event of a disease outbreak • Training programs for staff for the implementation of SOPs • Knowledge of AQUAVETPLAN Prawn Superpowers Summit 31 July 2012, QLD

9. Biosecurity Plan- What to consider? • Risk based approach • Use HACCP to identify critical control points • Broodstock facility • Hatchery • Growout ponds • Living document, requires regular update Prawn Superpowers Summit 31 July 2012, QLD

10. What else do we need to consider? • Prevention of pathogen entry on farm • Green prawn/crustacea from elsewhere • Broodstock and Post Larvae from elsewhere • Incoming water sources • Feed and Equipment (eg disinfect fish boxes) • Staff • Prevention of spread by vectors e.g. vermin, people, animals (translocation), environmental factors, feed, equipment • Prevention of disease transmission • farm to farm • farm to wild stocks Prawn Superpowers Summit 31 July 2012, QLD

11. Assessing Risk • High Risk: Untested and tested live prawns (adults and juveniles) from declared positive farms/zones • Medium Risk: Uncooked, dead prawn (bait) from known contaminated zones; Importation and use of fresh/frozen feeds from positive zones • Low Risk: Fresh/frozen feed from negative zones; prawns that have health certification, cooked crustaceans and prawn meal (heat treated) • Consider severity of risk as well as likelihood of the event occurring IRA helps inform the priority of decisions around risk management Prawn Superpowers Summit 31 July 2012, QLD

12. PATHOGEN: • Detection • Knowledge and understanding of disease transmission • Virulence factors • ENVIRONMENT: • Water quality • Diet • Biosecurity/ pathogen entry • SHRIMP FACTORS: • Age • Nutritional status • Stocking density • Immunity Prawn Superpowers Summit 31 July 2012, QLD

13. Environmental Parameters for testing • Oxygen • Salinity • pH • Nitrogenous waste • Toxic Algae- egheterosigma • Temperature Prawn Superpowers Summit 31 July 2012, QLD

14. Tools for prevention of disease:Surveillance • Surveillance of stock • Targeted sampling of stock • Normal vs. Abnormal • Adequate numbers for sampling • Correct sampling technique • Sensitivity and Specificity of chosen test assay • Coverage of shipment/population Prawn Superpowers Summit 31 July 2012, QLD

15. Detection of disease • What are the major diseases we are concerned with? • See National list of Reportable Diseases of Aquatic Animals • Exotic and Endemic • Can we identify abnormal/affected prawns? • How do we screen? And how often? • Which batches should be surveyed? • All ponds? • All hatchery tanks? Prawn Superpowers Summit 31 July 2012, QLD

16. Sample size for freedom from disease testing? • Desirable to have confidence interval of 95% • Depends on the anticipated prevalence of the disease in the tested population • Population size affects sample number- individual for each farm • Use EpiTools- FreeCalc from Ausvet website free download • OIE provide some guidance on testing (Aquatic Code) • Aquatic veterinarian may assist Prawn Superpowers Summit 31 July 2012, QLD

17. Tools for prevention of disease:Control points • Stock only accepted from hatchery with a tested known disease status • Stress test stock- don’t stock poor quality PL’s • Test 4 weeks into growout for GAV load • Requires good recording system Prawn Superpowers Summit 31 July 2012, QLD

18. Disease Detection • The techniques used will depend on the disease of concern. A field-veterinarian can advise you on the appropriate tests. • OIE Diagnostic Manual specify tests for listed pathogens • PCR • Isothermal technique (I-Screen): Cheaper and available for TSV and WSSV • Shrimple: WSSV • Histology Prawn Superpowers Summit 31 July 2012, QLD

19. Disease Outbreak: Control of disease • Isolate the affected animals- install quarantine barriers, stop water exchange, minimise aerosol, implement movement controls (staff, feed, equipment) • Confirm diagnosis with lab samples • Trace-back- identify potential source • Trace forward- identify where it may have already spread to • Notification: neighboring farms, authorities (State) • Follow an AQUAVETPLAN Emergency Disease Response Manual if available • Emergency harvest or Cull and disinfection option • Controlling vectors (birds) Prawn Superpowers Summit 31 July 2012, QLD

20. Handling of Samples:Laboratory diagnostics • PCR: • Live samples are preferred • Haemolymph from adult prawn • Quick frozen -20 degree frozen samples • <2-3gram pleopods or haemolymphfrom larger prawns preserved in 70% ethanol • Bacteriology: • General microbiology techniques • Use of microbiological labs for identification of disease • Sensitivity Prawn Superpowers Summit 31 July 2012, QLD

21. Handling samples for diagnostic investigation • Histology: Preserve tissue in Davidson’s fixative • Larvae and PL are to be immersed in a minimum of 10 volumes of fixative • For PL >20mm in length, a fine needle is to make a small incision that breaks and slightly lifts the cuticle in the midline of the back • Adults: Inject the fixative into the following sites: • Hepatopancreas • Region anterior to the HP • Anterior abdominal region • Posterior abdominal region • Prawns >12g should be transected down the midline before preservation

22. Vectors of disease • Movement of people/clothing: • Foot baths • Hand sprays • Disposable clothing • Full change of clothes • Showering • Work clothes stay at work • Disallow people to leave infected area Prawn Superpowers Summit 31 July 2012, QLD

23. Vectors of disease • Vermin/Pests • Bury/compost/burn affected stock • Lime/chlorine • Restrict access: netting, shooting, fencing Prawn Superpowers Summit 31 July 2012, QLD

24. Vectors of disease ISA outbreak- Sanitary barriers used • Equipment • Netting, vehicles (tractors, boats, forklifts, etc.), buckets, cleaning instruments, feed bins, etc. • Allocated equipment for different units on farm • Do not remove equipment off farm • Disinfection- correct chemical, pre-cleaning, sufficient contact time Prawn Superpowers Summit 31 July 2012, QLD

25. Vectors of disease • Movement of stock • Disallow all movement, all farms • Surveillance • Batch test pre-movement • Monitor post-movement • Feed Stuffs • Heat treated • Require traceability Prawn Superpowers Summit 31 July 2012, QLD

26. Vectors of disease • Water: Consider influent and effluent risks • Water treatment procedures- chlorination • Source of water: well water, sand filtered • Crab exclusion by fencing • Aerosol risks from paddlewheels • Stop all effluent discharge • Recirculation farm design Prawn Superpowers Summit 31 July 2012, QLD

27. Disease Outbreak- Eradication • Stock destruction- humane killing • Safe disposal of mortalities i.e. deep burial/compost • Mortality bins should be double bagged and decontaminated after transportation • Disinfection of potential vectors e.g. incoming and outgoing water, equipment • Proof of freedom testing FMD outbreak UK Prawn Superpowers Summit 31 July 2012, QLD

28. Farm Biosecurity Model Example

29. Decision Making PANIC What happens when you have detected disease? Prawn Superpowers Summit 31 July 2012, QLD

30. Contingency Planning Facilitates quick recovery to production through rapid response and effective implementation of biosecurity procedures at acceptable cost Prawn Superpowers Summit 31 July 2012, QLD

31. Acknowledgements • Images in this talk were provided by: • Mark Oliver, LMC Training • Ben Diggles, Digsfish Services • Department of Fisheries, Brunei Darassalum • A Lagno National Fisheries Service Chile • Don Lightner, University of Arizona • Other web-based images