The Detection of Ciguatera Toxins in NSW Spanish Mackerel
University of Technology Sydney (UTS)
Ciguatera Fish Poisoning (CFP) causes the largest number of seafood-related food safety incidents in Australia. In NSW and southern QLD waters, CFP is mostly related to Spanish Mackerel (Scomberomorus commerson). Ciguatoxins (CTXs) produced by marine microalgae (Gambierdiscus spp), are polyether toxins that accumulate in fish and cause CFP when fish are eaten. CTXs are heat stable, odourless, tasteless, and toxic at low concentrations, therefore it is very difficult to distinguish toxic fish. In NSW, since 2014, 31 people have contracted CFP after consuming Spanish Mackerel caught locally, mostly through recreational fishing. Validated commercial monitoring methods for CTXs are unavailable internationally, although research tools for CTX measurement have been developed. Regulatory methods for CFP prevention are to avoid certain fish species, fish of certain sizes (ie >10kg), or fish from certain regions. In Australia, effective prevention methods have not been clearly evaluated. This results in Spanish Mackerel that are safe to eat potentially being excluded from sale, resulting in significant losses (ie > ~$200k p.a in NSW). This project addresses this issue, which was identified as high priority in the Australian ciguatera research strategy formulated at a recent workshop (27-28th March, 2019). In 2014, FRDC (Tactical Response) and the NSW Recreational Fisheries Trust funded an initial study on the incidence of CTXs in NSW Spanish Mackerel. CTX was present in flesh and liver samples (1-7% incidence), and was not clearly correlated with the weight of individual fish. This information showed that CFP risk management may require reassessment. This project will advance knowledge by: evaluating methods of detection of CTXs; determining detailed predictive data on CTX incidence; and evaluating environmental and biological factors associated with CTX in Spanish Mackerel to allow for an evaluation of risk assessment strategies. This information will benefit industry by enhancing consumer safety and industry confidence, and enabling the sale of safe Spanish Mackerel.
1. Determine industry CTX needs and conduct of review of available CTX measurement tools (including cell based assays, ELISA kits, and LCMS) against these needs. Conduct an assessment of the currently available screening tools to determine which, if any, hold promise for industry use. Conduct a viability assessment for how a tool might be used in industry or, if none of the currently available tools are appropriate, make recommendations for future activities to develop a rapid screening tool that meets industry needs.
2. Obtain samples of flesh and liver from ~300 individual Spanish Mackerel of all sizes caught in Industry relevant regions of NSW waters over a period of 2 years, as well as length, weight, sex and site information, with the participation of the Sydney Fish Market and commercial fishing Cooperatives. Obtain samples from any individual Spanish Mackerel associated with illnesses in NSW or QLD. Measure CTX1B and other available CTX analogs using best practice methods identified in Objective 1.
3. Conduct statistical data analyses of all available data on CTX concentrations in Spanish Mackerel in comparison to biological and environmental variables.Develop recommended options for food safety risk management for Spanish Mackerel in NSW that will allow for a viable industry while protecting public health.