Assessing the risk of pathogenic Vibrio species in Tasmanian oysters

The South Australian Research and Development Institute (SARDI) in collaboration with the Tasmanian oyster industry and regulators, University of Tasmania and Plant and Food Research New Zealand undertook a survey of significant foodborne Vibrio species (Vibrio parahaemolyticus and Vibrio vulnificus) in eleven major commercial Tasmanian shellfish production areas. Surveyed growing areas were selected in consultation with the Tasmanian Shellfish Market Access Program (ShellMAP) and Tasmanian Primary Produce Safety Program to represent a range of production environments and different production practices, as well as various regions with and without prior history of foodborne V. parahaemolyticus illnesses. Commercial Pacific Oysters (Magallana gigas) and Blue Mussels (Mytilus galloprovincialis) were tested for Vibrio levels over three summer/autumn and two winter/spring periods between 2020-2022. Local environmental data, including harvest water and air temperature, rainfall, river flow and salinity, were also collected. The results of the survey have been used to develop the first Australian risk profile for Vibrio, specific to commercial Tasmanian shellfish, and to identify significant environmental drivers of Vibrio risk in individual surveyed harvest areas.