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Disease Risk Assessment Report for Proposed Salmon Farms at Stewart Island, New Zealand

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Disease Risk Assessment Report for Proposed Salmon Farms at Stewart Island, New Zealand Appendix K Disease risk assessment December 2019 │ Status: Final │ Project No.: 310001082 │ Our ref: Appendice header pages.docx ASSESSMENT OF ENVIRONMENTAL EFFECTS – DISEASE RISK ASSESSMENT REPORT FOR PROPOSED SALMON FARMS AT STEWART ISLAND, NEW ZEALAND DigsFish Services Report: DF 19-02 13 May 2019 ASSESSMENT OF ENVIRONMENTAL EFFECTS – DISEASE RISK ASSESSMENT REPORT FOR PROPOSED SALMON FARMS AT STEWART ISLAND, NEW ZEALAND Prepared by: Ben Diggles PhD Prepared for: Ngai Tahu Seafood Resources DigsFish Services Pty. Ltd. 32 Bowsprit Cres, Banksia Beach Bribie Island, QLD 4507 AUSTRALIA Ph/fax +61 7 3408 8443 Mob 0403773592 [email protected] www.digsfish.com Contents Abbreviations and Acronyms ............................................................................................................................ 6 Executive Summary ........................................................................................................................................... 7 1.0 Introduction .......................................................................................................................................... 9 2.0 Site location ......................................................................................................................................... 11 3.0 Description of the existing environment - Disease Agents in Chinook salmon and Bluff oysters in New Zealand .................................................................................................................................................... 17 4.0 Assessment of Environmental Effects ................................................................................................. 19 4.1 Hazard Identification ........................................................................................................................ 20 4.2 Elimination of insignificant diseases of salmon .................................................................................. 22 4.2.1 Non-infectious diseases ................................................................................................................ 22 4.2.2 Bacteria ........................................................................................................................................ 23 4.2.3 Fungi ............................................................................................................................................ 25 4.2.4 Protozoa (including microsporidians) ............................................................................................ 26 4.2.5 Metazoa........................................................................................................................................ 27 4.3 Elimination of insignificant diseases of Bluff oysters .......................................................................... 29 4.3.1 Non-infectious diseases ................................................................................................................ 29 4.3.2 Viruses ......................................................................................................................................... 29 4.3.3 Bacteria ........................................................................................................................................ 30 4.3.4 Protozoa ....................................................................................................................................... 30 4.3.5 Metazoa........................................................................................................................................ 32 4.4 The diseases of concern requiring detailed risk assessment ................................................................ 33 5.0 Detailed Risk Assessment.................................................................................................................... 34 5.1 Infection with Aquatic Birnavirus ...................................................................................................... 34 5.2 Infection with Piscirickettsia-like bacteria (NZ-RLO) ........................................................................ 39 5.3 Amoebic/Nodular Gill Disease .......................................................................................................... 44 5.4 Sea lice ............................................................................................................................................. 47 5.5 Whirling Disease .............................................................................................................................. 52 5.6 Bonamia exitiosa .............................................................................................................................. 56 5.7 Bonamia ostreae ............................................................................................................................... 61 5.8 Bucephalus longicornutus ................................................................................................................. 65 5.9 Mudworms (Polydora sp., Boccardia sp.) .......................................................................................... 69 6.0 Recommendations for disease risk mitigation .................................................................................... 73 6.1 Infection of salmon with Piscirickettsia-like bacteria ......................................................................... 73 6.2 Infection of Bluff oysters with Bonamia exitiosa................................................................................. 75 6.3 Infection of Bluff oysters with Bonamia ostreae ................................................................................. 75 6.4 Infection of Bluff oysters with Bucephalus longicornutus ................................................................... 76 4 www.digsfish.com 6.5 Infection of Bluff oysters with mudworms .......................................................................................... 76 7.0 Conclusions ......................................................................................................................................... 77 8.0 References ........................................................................................................................................... 78 Appendix 1 – Risk Assessment Methodology ................................................................................................ 110 Release assessment ................................................................................................................................. 110 Exposure assessment ............................................................................................................................... 110 Consequence assessment ......................................................................................................................... 111 Risk estimation ....................................................................................................................................... 113 Risk mitigation........................................................................................................................................ 114 Option evaluation .................................................................................................................................... 114 5 www.digsfish.com Abbreviations and Acronyms AEE Assessment of environmental effects AGD Amoebic gill disease ALOP Appropriate level of protection CAN Controlled Area Notice ERM Enteric redmouth disease EUS Epizootic ulcerative syndrome GDAS Gastric dilation and air sacculitis IHN Infectious Haematopoietic Necrosis IHNV Infectious Haematopoietic Necrosis Virus IPN Infectious Pancreatic Necrosis IPNV Infectious Pancreatic Necrosis Virus ISA Infectious Salmon Anaemia ISAV Infectious Salmon Anaemia Virus MPI Ministry for Primary Industries NSW New South Wales, Australia NZKS New Zealand King Salmon Ltd NZ-RLO New Zealand rickettsia-like agent, 3 known genotypes of PLB including one closely related to Piscirickettsia salmonis OIE World Organisation for Animal Health (formerly Office International des Epizooties). PLB Piscirickettsia -like bacteria RA Risk analysis RLO Rickettsia-like organism TAB Tasmanian aquabirnavirus TEM Transmission electron microscopy TCID 50 Tissue culture infectious dose 50% endpoint VHS Viral Haemorrhagic Septicaemia VHSV Viral Haemorrhagic Septicaemia Virus Version control First draft: 13 March 2019 Final draft (unmitigated risk assessment): 13 May 2019 Final report: Disclaimer: DigsFish Services have taken all reasonable care and diligence to ensure the information contained in this report is accurate at the time of publication. However, this report is offered as general advice only, we do not warrant the accuracy of the information contained within and accept no liability for any loss or damage that may result from reliance on this information. 6 www.digsfish.com Executive Summary Ngai Tahu Seafood has proposed to locate a new salmon farming area on the east coast of Stewart Island in Foveaux Strait, New Zealand, to accommodate up to 110 offshore seacages (125-250 meters in diameter) producing up to 30,000 metric tonnes of chinook salmon ( Oncorhynchus tshawytscha ) per annum. As part of the assessment of environmental effects (AEE) for this proposal, DigsFish Services Pty Ltd was asked to undertake a disease risk assessment to consider the potential for fish and shellfish diseases
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