Biodiversity Risk and Benefit Assessment for Pacific oyster (Crassostrea gigas) in South Africa Prepared in Accordance with Section 14 of the Alien and Invasive Species Regulations, 2014 (Government Notice R 598 of 01 August 2014), promulgated in terms of the National Environmental Management: Biodiversity Act (Act No. 10 of 2004). September 2019 Biodiversity Risk and Benefit Assessment for Pacific oyster (Crassostrea gigas) in South Africa Document Title Biodiversity Risk and Benefit Assessment for Pacific oyster (Crassostrea gigas) in South Africa. Edition Date September 2019 Prepared For Directorate: Sustainable Aquaculture Management Department of Environment, Forestry and Fisheries Private Bag X2 Roggebaai, 8001 www.daff.gov.za/daffweb3/Branches/Fisheries- Management/Aquaculture-and-Economic- Development Originally Prepared By Dr B. Clark (2012) Anchor Environmental Consultants Reviewed, Updated and Mr. E. Hinrichsen Recompiled By AquaEco as commisioned by Enterprises at (2019) University of Pretoria 1 | P a g e Biodiversity Risk and Benefit Assessment for Pacific oyster (Crassostrea gigas) in South Africa CONTENT 1. INTRODUCTION .............................................................................................................................. 9 2. PURPOSE OF THIS RISK ASSESSMENT ..................................................................................... 9 3. THE RISK ASSESSMENT PRACTITIONER ................................................................................. 10 4. NATURE OF THE USE OF PACIFIC OYSTER ............................................................................ 11 4.1. REASONS FOR FARMING WITH PACIFIC OYSTER.................................................................. 12 5. LEGAL CONTEXT ......................................................................................................................... 14 5.1. CATEGORIZATION OF ALIEN AND INVASIVE SPECIES .......................................................... 14 5.2. STATUTORY CLASSIFICATION OF PACIFIC OYSTER ............................................................. 15 5.3. LIST OF RESTRICTED ACTIVITIES ............................................................................................. 17 6. TARGET SPECIES: PACIFIC OYSTER ....................................................................................... 20 6.1. TAXONOMY ................................................................................................................................... 20 6.2. ORIGINATING ENVIRONMENT .................................................................................................... 21 6.3. KEY PHYSIOLOGICAL CHARACTERISTICS .............................................................................. 21 6.4. FEEDING AND DIETARY ASPECTS ............................................................................................ 22 6.5. LIFECYCLE AND GROWTH ......................................................................................................... 23 6.6. REPRODUCTION .......................................................................................................................... 23 6.7. ENVIRONMENTAL TOLERANCES .............................................................................................. 24 6.8. NATURAL ENEMIES, PREDATORS AND COMPETITORS ........................................................ 25 6.9. POTENTIAL TO HYBRIDISE ........................................................................................................ 26 6.10. PERSISTENCE AND INVASIVENESS .................................................................................. 26 6.11. PROBABILITY OF NATURALISATION ................................................................................. 27 6.12. ABILITY TO CREATE ECOSYSTEM CHANGE .................................................................... 28 6.13. POSSIBLE IMPACTS ON BIODIVERSITY ............................................................................ 29 6.14. POSSIBLE IMPACTS ON OTHER NATURAL RESOURCES .............................................. 30 6.15. ACTING AS A VECTOR OF OTHER ALIEN SPECIES ........................................................ 30 6.16. HISTORY OF TRANSLOCATION AND CULTIVATION ........................................................ 31 7. THE RECEIVING ENVIRONMENT ................................................................................................ 33 7.1. CLIMATE AND HABITAT MATCH ................................................................................................ 33 7.2. TOOLS TO IDENTIFY SENSITIVE AREAS .................................................................................. 35 8. THEORY BEHIND ECOLOGICAL RISK ASSESSMENT ............................................................. 36 8.1. THE PRECAUTIONARY AND OTHER PRINCIPALS .................................................................. 37 8.2. METHODOLOGY IN THE RISK ASSESSMENT .......................................................................... 38 8.3. THE RISK PATHWAY ................................................................................................................... 40 8.4. SCALES AND CATEGORISATION OF RISK ............................................................................... 41 8.5. PERCEPTION OF RISK ................................................................................................................ 46 8.6. RISK COMMUNICATION .............................................................................................................. 46 9. SPECIFIC FRAMEWORK ASSESSMENT FOR PACIFIC OYSTER............................................ 47 2 | P a g e Biodiversity Risk and Benefit Assessment for Pacific oyster (Crassostrea gigas) in South Africa 9.1. NATURALISED IMPACTS OF PACIFIC OYSTERS .................................................................... 47 9.2. INVENTORY OF POTENTIAL PATHWAYS AND RISKS ............................................................ 48 9.3. DISCUSSION OF RISK PATHWAYS ............................................................................................ 48 9.3.1. THE PATHWAY OF ESCAPE ................................................................................................ 49 9.3.2. THE PATHWAY OF DISEASE ............................................................................................... 51 9.4. DISCUSSION OF RISK ENDPOINTS ........................................................................................... 52 9.4.1. PHYSICAL ABIOTIC DAMAGE TO THE ENVIRONMENT ................................................... 52 9.4.2. SPECIES DISPLACEMENT ................................................................................................... 53 9.4.3. COMPETITION - FOOD, HABITAT & OTHER RESOURCES .............................................. 53 9.4.4. HYBRIDIZATION .................................................................................................................... 54 9.4.5. EFFECTS OF DISEASE ......................................................................................................... 54 9.5. ASSESSMENT SCORING OF RISK LEVELS .............................................................................. 56 9.5.1. RISK PATHWAYS .................................................................................................................. 56 9.5.2. RISK ENDPOINTS/IMPACTS ................................................................................................ 59 9.6. SUMMARY OF RISK PROFILE..................................................................................................... 60 10. KEY ECONOMIC, SOCIAL AND SOCIETAL CONSIDERATIONS .............................................. 66 11. BALANCED COST OF ERADICATION ........................................................................................ 67 12. RISK MONITORING ...................................................................................................................... 67 13. RISK CONTROL MEASURES AND MITIGATION ....................................................................... 68 14. RESEARCH NEEDS ...................................................................................................................... 69 15. BENEFIT / RISK TRADE-OFF....................................................................................................... 70 16. RECOMMENDATIONS .................................................................................................................. 70 17. CONCLUSION ............................................................................................................................... 71 REFERENCES ...................................................................................................................................... 72 LIST OF APPENDIXES Appendix A: Risk scoring methodology for Crassostrea gigas and guidance supplied by the F-ISK toolkit (Copp et al. 2008). 3 | P a g e Biodiversity Risk and Benefit Assessment for Pacific oyster (Crassostrea gigas) in South Africa EXECUTIVE SUMMARY Internationally, alien species provide a valuable food source and an economic opportunity in both the fisheries and aquaculture sectors. In South Africa, aquaculture is composed of a blend of indigenous and non-indigenous species. However, breeding and domestication of indigenous species requires time, technological and financial resources, whilst there are already alien species with proven aquaculture potential that could be