Improving risk management of paralytic shellfish toxins (PST) in the Blacklip Abalone (Haliotis rubra rubra)
SARDI Food Safety and Innovation
Whilst Alexandrium blooms on the east coast of Tasmania and in New South Wales have caused abalone harvest closures in the past, until 2017 only low levels of paralytic shellfish toxins (PST) had been detected in abalone from these blooms (max. 0.3 mg STX.2HCl equiv/kg). This is in contrast to elevated levels of PST found during Gymnodinium blooms in southern Tasmania. However, during the 2017 bloom, abalone were found to exceed the bivalve regulatory limit at 1.2 mg STX equiv/kg. A precautionary risk management approach has been taken to abalone harvest during Alexandrium blooms in Australia. The closure of abalone harvest zones is based on information arising from the bivalve shellfish monitoring program. The impact on the fishery on the east coast of Tasmania has been more than 25 block closures to date, some of which have been continuous for over 2 years. This conservative approach has been adopted due to both the paucity of information on PST accumulation in abalone from Alexandrium blooms, and the high consequence of any PST detection in overseas markets. Current testing costs are around $5,000 per site (minimum of 5 animals, two tissues, $500 per test), severely limiting the amount of testing that occurs. This proposal has been developed to improve the risk management of PST in abalone, particularly to reduce the economic impact on fishers. It will also increase the understanding of the risk that Alexandrium species pose to accumulation of PST in abalone. It includes field and tank studies, with costs of the latter significantly offset by the biotoxin contamination facility that will operate at Roseworthy between March and September 2018, funded through an Australian Seafood CRC grant .
1. Determination of PST uptake by abalone from two routes: exposure to cultures of Alexandrium tamarense and contaminated feed
2. Determination of relative risk of PST accumulation in abalone compared to Southern Rock Lobster in two field sites
3. Validation of rapid test kits for PST analysis in abalone foot and viscera tissues