Multi-trophic paralytic shellfish toxin risk and management across seafood sectors in Tasmania

Multi-trophic biotoxin risk management is critically important to regions that suffer from extensive blooms of paralytic shellfish toxin (PST) producing algae. In Australia, Tasmania's east and south-east coasts are hotspots for PST activity due to recurrent blooms of Alexandrium catenella and Gymnodinium catenatum occurring in differing geographic regions and seasonal patterns. Toxins have been measured above bivalve regulatory levels in filter feeders, predatory crustaceans and herbivorous grazers at maximum levels of 340, 13.6 and 3.0 mg STX.2HCl equiv. kg^-1 respectively, affecting commercial and recreational fisheries with a combined annual value of USD 103M. Toxin accumulation and depuration rates are highest in bivalve shellfish, followed by lobster and then abalone. Managing PST risk across these multiple seafood species in an area of recurrent bloom activity is challenging. Currently a siloed approach is taken, with diverse strategies for each species that reflect the harmful algal bloom dynamics and varied fishing activities. This review of Tasmanian data and the following stakeholder consultation identified benefits to adopting an integrated approach to risk management across all seafood species. Benefits included cost efficiencies (USD 54,100 per annum), improved data sharing for real-time awareness, streamlined communication and improved cross-sector collaboration.