Monitoring and management of paralytic shellfish toxins in Southern Rock Lobster, Tasmania, Australia

The Tasmanian Southern Rock Lobster (Jasus edwardsii) fishery has been challenged by recurrent dinoflagellate blooms of Alexandrium catenella since 2012. The initial bloom resulted in the first ever closure of an Australian lobster fishery due to marine biotoxins and exposed several key knowledge gaps for managing food safety and market access risk. To fill these gaps, experimental studies were conducted to determine paralytic shellfish toxin (PST) toxicokinetics. Adult male lobsters fed highly toxic mussels (6 mg STX.2HCl eq kg^-1) accumulated PST in the hepatopancreas at an exponential rate of 6% per day, reaching a maximum level of 9 mg STX.2HCl eq kg^-1 in three weeks. However, lobsters exposed to toxic algae culture suspensions at 2 x 10⁵ cells L^-1 did not accumulate any toxin. Neither accumulation of PST nor exposure to toxic cells resulted in any gross impact on the health of lobsters, as assessed by a comprehensive range of behavioural, immune, nutritional and biochemical indicators. Field studies over a period of eight years confirmed the ability of lobster hepatopancreas to rapidly accumulate and depurate toxins in the wild, with a high degree of variability. Analysis of 496 hepatopancreas samples collected during A. catenella blooms identified high risk sites and seasons; demonstrated the usefulness of mussels as sentinel species for indicating PST risk; and enabled quantification of the confidence level associated with current risk management sampling practices. The combined experimental and field results have led to improved risk management for this AUD 97M wild fishery.