Risk assessment and predictive modelling – a review of their application in aquatic animal health

Abstract

Risk analysis has only been regularly used in the management of aquatic animal health in recent years. The Agreement on the Application of Sanitary and Phytosanitary measures (SPS) stimulated the application of risk analysis to investigate disease risks associated with international trade (import risk analysis-IRA). A majority (9 of 17) of the risk analyses reviewed were IRA. The other major focus has been the parasite of Atlantic salmon-Gyrodactylus salaris. Six studies investigated the spread of this parasite, between countries, rivers and from farmed to wild stocks, and clearly demonstrated that risk analysis can support aquatic animal health policy development, from international trade and biosecurity to disease interaction between wild and farmed stocks. Other applications of risk analysis included the spread of vertically transmitted pathogens and disease emergence in aquaculture. The Covello-Merkhofer, risk analysis model was most commonly used and appears to be a flexible tool not only for IRA but also the investigation of disease spread in other contexts. The limitations of the identified risk assessments were discussed. A majority were qualitative, partly due to the lack of data for quantitative analysis, and this, it can be argued, constrained their usefulness for trade purposes (i.e. setting appropriate sanitary measures); in other instances, a qualitative result was found to be adequate for decision making. A lack of information about the disease hazards of the large number of fish species traded is likely to constrain quantitative analysis for a number of years. The consequence assessment element of a risk analysis was most likely to be omitted, or limited in scope and depth, rarely extending beyond examining the evidence of susceptibility of farmed and wild species to the identified hazard. The reasons for this are discussed and recommendations made to develop guidelines for a consistent, systematic and multi-disciplinary approach to consequence assessment. Risk analysis has improved decision making in aquatic animal health management by providing a transparent method for using the available scientific information. The lack of data is the main constraint to the application of risk analysis in aquatic animal health. The identification of critical parameters is an important output from risk analysis models which should be used to prioritise research. 2007.