Biosecurity, in its simplest term, can be defined as the set of procedures undertaken to prevent, control and eradicate infectious diseases in organisms. This is a basic definition applied to many agricultural industries. With the emergence of new technologies, however, this definition has been modified and adapted for different circumstances, for example, those related to bioterrorism, genetically modified organisms and laboratory animals.
Biosecurity, however, can be seen as a tool, as a mechanism developed to assist and protect agro-industries. Biosecurity in salmonid aquaculture has been in place for several decades. In the shrimp culture industry, however, it was not until the outbreaks of Taura syndrome virus (TSV) in the Americas and white spot syndrome virus (WSSV) in Asia in the early 1990s that the need for rigorous biosecurity practices was highlighted.
In safeguarding the health of any aquatic population, one must consider the threats from pathogens which may be well characterised or new, endemic or exotic, and the exposure to these can either be prevented or minimised. Safeguarding the health of aquatic animals can be done through the use of an array of physical and hygiene practices at the national, aquatic system and/or farm level.
There is also a parallel requirement to ensure that the disease management or intervention practices that are used are applied in an ethical, sustainable manner with no detrimental impact to the farmed population, the environment or to the end consumers of the final products. Within a robust biosecurity framework, each of these prerequisites requires strategic and integrated policies involving key stakeholders at various levels: farms, industry and governments.
Biosecurity at different levels
Biosecurity should be looked at as a whole. Even if, for example, a shrimp producer has good management practices and a biosecurity program in place, this might not be enough to avoid contamination of the production area. If there are no biosecure hatcheries supplying ‘clean’ post larvae, then the risks of introducing new pathogens into a system are always high. The same principles apply to a biosecurity program at the country level.
The sanitary status of neighbouring countries must be considered at the moment of establishing international trade. Taking all of these into consideration, comprehensive biosecurity programs should have different levels of regulation: international level, national level and producer level.
This article will focus on biosecurity at the international level whilst biosecurity at the two other levels will be addressed in subsequent issues of Aqua Culture Asia Pacific.
Biosecurity at the international level
This level of regulation centres on the competency of national governments and the rigour by which legislation, surveillance (where appropriate) and testing are upheld. The main objectives are to develop a system to protect the industry under consideration. It is also to establish rules and mechanisms of trade between countries producing similar products. Enforcement of national legislations between trading nations will help to prevent the import of contaminated shipments of aquatic products and minimise the illegal transboundary movement of stock.
The first step is for the country importing the aquatic products to establish their own sanitary status regarding the aquatic species. Part of this should involve a national screening program of wild and cultured populations for specific pathogens of concern. The World Animal Health Organisation, for example, has an Aquatic Code with a list of notifiable diseases for each aquatic species. Following surveillance, certain countries may be able to demonstrate and declare that they are free of a specific pathogen.
Zoning and compartmentalisation
If, however, a pathogen is found to be present within a country, it is critical to define where they are found and whether there are areas that are pathogen free. If these areas are delineated by geographical barriers, then these can be considered as zones and the group of animals within it constitutes a subpopulation.
In other situations, the appropriate application of management practices may produce a subpopulation that is free of the pathogen. These characteristics are the basis of what is called zoning and compartmentalisation - the first being when the subpopulation is limited by a natural or artificial geographical barrier, and, the second when the subpopulation is confined to a facility with special management practices in place.
In each case, the competent authorities of each country have the authority to designate zones or compartments based on health surveillance assessments of each subpopulation. Once a zone or a compartment is established, the competent authority must specify the surveillance system used to characterise the subpopulations, the method by which each subpopulation is identified and, the traceability system in place to permit each subpopulation to be tracked back to its point of origin.
Once zones and compartments are defined, then trade agreements can be established between countries. Importation of any commodity, however, runs the risk of introducing a pathogen into a country. In order to minimise the risk, an importing risk analysis (IRA) can be used as a decision making tool. In general terms, an IRA is a procedure based on risk identification, risk assessment, risk management and risk communication. The IRA can be used by the importing country to impose import conditions or even to refuse importation.
Fish Vet Group's Biosecurity Part II (National level) and Biosecurity Part III (Farm level) will be out later in the year.