Risk Assessment Methods in Aquaculture

Risk assessment methods vary considerably depending on the risk analysis sector (see Reantaso, Arthur and Subasinghe 2008).  The risk assessment component of import risk analysis consists of four components. In release assessment, the biological pathways necessary for an importation activity to “release” (introduce) a hazard into the importing country are defined and the likelihood of that complete process occurring is estimated. Or, more simply stated, release assessment determines the pathways that a pathogen can move with the commodity from the exporting country to the border of the importing country and the likelihood of this occurring. Similarly, exposure assessment determines the pathways by which susceptible populations in the importing country can be exposed to the pathogen and the likelihood of this occurring. Examples of exposure pathways can be found in many of the risk analyses cited in Links section. Consequence assessment identifies the potential biological, environmental and socio-economic consequences expected to result from pathogen introduction, while risk estimation calculates the overall risk posed by the hazard (the unmitigated risk) by combining the likelihood of entry and exposure with the consequences of establishment.

   Pathway analysis is an important feature of the risk analysis process for most sectors. Through scenario diagrams, the possible routes (pathways) and the individual events or steps in each pathway that need to occur for a given pathway to be successfully completed can be identified. In pathogen risk analysis, this approach assists by providing a logical process by which the critical risk steps (events) leading to pathogen introduction and establishment in an importing country, new drainage basin, farming system, etc. can be identified. This allows for the probability of each event occurring to be estimated, leading to an overall estimate of the probability of a given pathway being completed. Further, pathway analysis is also an important tool that can be used to estimate the likely effectiveness of a risk mitigation measure (health certification, inspection, quarantine, etc. (Related information is available in the Risk Management in Aquaculture Section).