The potential for poisoning events from biotoxin contamination of shellfish is a growing concern for all shellfish producers, aquaculture managers and the general public in Australia.
Outside of shellfish consumption, the occurrence of marine biotoxins has direct implications for human health for recreational users of the marine and coastal areas in which these blooms occur.
There are also implications for other seafood products which can accumulate biotoxins, as well as for ballast water management and the shipping sector, for general environmental protection / human health, and for sewage processors (as mentioned above, there are strong linkages between algal blooms and sewage output). However, the immediate concern for seafood industries is to assess the need to undertake sampling and monitoring programs in shellfish producing areas and to determine what risks exist for other seafood industries.
There is a genuine and urgent need to update the work undertaken in 1993, and supplement this work with additional information in order to develop a consistent national approach to biotoxin monitoring. The resulting monitoring strategy will be based on an appropriat and targeted sampling strategy, developed through an assessment of need and risk, in order to support the development and implementation of effective management regimes for the shellfish industry.
Final report
In Australia aquaculture and wild harvest of shellfish is an economically important and growing industry. The safety of these products as a food source is of utmost importance from both public health and economic points of view. One of the potential problems faced by shellfish growers is the contamination of their product with marine biotoxins. These toxins are chemical compounds that are produced by specific naturally occurring marine microalgae. Most microalgae (often referred to as phytoplankton) are actually an important food source of the shellfish. However, if biotoxins are produced they can induce human illness if contaminated shellfish are consumed. This is not only a problem for commercially produced or harvested shellfish, but also for recreational and subsistence shellfish gatherers.
Biotoxins are not only a problem for Australia, as most coastal countries in the world have had, or have the potential for, problems with marine biotoxin contamination in shellfish. In order to manage this problem, many countries have monitoring programs aimed at both the detection of the species of microalgae that produce the toxins, and at the detection of toxins in the shellfish. Phytoplankton monitoring is a faster and cheaper test than shellfish flesh testing, and provides an early warning of the potential for contamination of shellfish with marine biotoxins. However, the two types of testing need to be performed in conjunction with each other. Internationally, food safety regulations are based on the levels of toxins in shellfish, and it is these results that should generally be used for regulatory decisions.
Internationally the impacts of toxic microalgae on both public health and the economy are increasing in frequency, intensity and geographic distribution. As aquaculture expands, and its importance as both food and income sources increases for many countries, it is expected that these impacts of marine biotoxins will also increase. As international markets become more conscious of the safety of the foodstuffs they import, they impose safety regulations and can also impose non-trade barriers.
Australia’s shellfish industry’s market has a large domestic component, worth approximately $90M per year. There is, perhaps, less external pressure on Australia to manage these problems. However the domestic consumers are no less important than overseas consumers, and hence there remains the need for protection from marine biotoxins. There is a need for controls between states, just as there is a need for controls for exported product. The proposed strategy is for a voluntary agreement between states, and spells out the acceptable monitoring programs, controls and regulations that must be met in order to ‘export’ shellfish to another signatory state. This “model ordinance” is fairly well accepted as an international standard for shellfish safety, along with the European Union directives, which must be met in order to export shellfish to the EU. This proposed strategy is supported by a Model Australian National Marine Biotoxin Management Plan (Cawthron Report No. 646).
A marine biotoxin monitoring program is a long-term commitment to protecting the public health of shellfish consumers, understanding more about the shellfish resource and assisting the industry to growing into the future. It requires regulatory commitment at Federal and State government level to maintain and police biotoxin standards.
Keywords: Biotoxins, aquaculture, shellfish, microalgae, monitoring programs.
