3. World Organisation for Animal Health (OIE) guidelines and other technical guidelines

To meet the aims and needs of modern society, biosecurity systems need to be based on robust and transparent scientific inputs to standard-setting processes, in particular those relating to trade in agricultural products (FAO, 2007a). One of the fundamental principles of the General Agreement on Tariffs and Trade (GATT), established after the end of World War II, ensured that all nontariff barriers to international trade should be prohibited. This was retained in full with the establishment of the World Trade Organization (WTO) in 1995 (Chillaud, 1996).

The 1995 WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) aims to minimize the effects of health restrictions on international trade. To achieve this, the animal health measures established by countries to ensure the protection of human and animal life and health are based on international standards, guidelines and recommendations, primarily those developed by the OIE, and the OIE code plays a central role in this process (Chillaud, 1996). The SPS Agreement requires states to not introduce or maintain health measures that result in a higher measure of protection than that advocated by these international standards, unless scientific justification for the need for such measures can be demonstrated (Chillaud, 1996). The SPS Agreement also emphasizes the need for transparency in import health measures that states enforce (Chillaud, 1996). Similarly, the Codex Alimentarius, established by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) of the United Nations in 1963, provides international food standards, guidelines and codes of practice, including those relating to veterinary drug residues that contribute to the safety, quality and fairness of international food trade. Through the SPS Agreement, the Codex also has far reaching implications for resolving trade disputes.

The OIE is recognized by its member countries as the international organization responsible for development and promotion of international animal health standards, guidelines and recommendations affecting safe international trade in live animals and their products. These are documented in the OIE Aquatic Animal Health Code (OIE, 2016) and the OIE Manual of Diagnostic Tests for Aquatic Animals (OIE, 2015).
Zoning and compartmentalization, with risk assessment and epidemiological disease surveillance and monitoring, form an essential component of biosecurity and import risk analysis (OIE, 2016). To keep abreast with changing challenges, the input of experts and working groups and the contributions of member countries result in an annual review and update of the Code and the Manual, and authorities should refer to the most recent issue. Central to these documents is a list of diseases that are notifiable to the OIE. Where new outbreaks of these diseases occur, the member states are obliged to report on these outbreaks to the OIE. For a disease to be listed, several standard criteria are applied (OIE, 2016):
• the disease has been shown to cause significant production losses at a national or multinational level;
• the disease has been shown to or scientific evidence indicates that it is likely to cause significant morbidity or mortality in wild aquatic animal populations;
• the agent is of public health concern;
• an infectious aetiology of the disease is proven;
• an infectious agent is strongly associated with the disease, but the aetiology is not yet known;
• likelihood of international spread exists, including via live aquatic animals, their products or fomites;
• several countries or countries with zones may be declared free of the disease based on the general surveillance principles outlined in the Code; and
• a repeatable and robust means of detection/ diagnosis exists.
Many countries in the world are members of the OIE, and as such have a commitment to apply the OIE standards through relevant national policy and legislation (Oidtmann et al., 2011). Supernational and political unions, such as the European Union (EU), may apply common policies and legal frameworks to ensure that member countries apply equivalent standards in order to facilitate trade between member states. In the EU, the Council Directive 2006/88/EC (on animal health requirements for aquaculture animals and products thereof, and on the prevention and control of certain diseases in aquatic animals) provides the instrument for the biosecurity framework applied in the EU with an emphasis on promoting prevention of aquatic animal diseases (Oidtmann et al., 2011). The directive is particularly relevant to countries outside of the EU, so-called third countries, wishing to export aquatic animals or their products to the EU. While standardizing aquatic animal health controls across the European Community (EC) to facilitate trade within the EU, it makes provision for protecting areas of higher health status. Such additional animal health control measures applying to certain diseases and areas may include a requirement for specific disease guarantees that will reflect on relevant model animal health certificates required for imports into the country from third countries. For example, England and Wales have import requirements for a number of diseases in addition to diseases considered exotic to the EC (Oidtmann et al., 2011).
The bulk of world aquaculture production takes place in Asia. The Asia Regional Technical Guidelines on Health Management for the Responsible Movement of Live Aquatic Animals, and their associated implementation plan, the Beijing Consensus and Implementation Strategy (FAO, 2000) have been adopted by Asian countries in a regional effort to reduce and manage the risk due to the transboundary movement of live aquatic animals (Mohan, Chinabut and Kanchanakhan, 2008). These guidelines provide a comprehensive framework for dealing with aquatic animal diseases emergencies.
A number of other international guidelines provide technical information on fisheries, aquaculture and biodiversity with information relevant to biosecurity.
The FAO Code of Conduct for Responsible Fisheries, adopted by member states on 31 October 1995, applies to both fisheries and aquaculture, and includes principles and international standards of behaviour for responsible practices with a view to ensuring the effective conservation, management and development of living aquatic resources, with due respect for the ecosystem and biodiversity (FAO, 2011). Further technical information on health management for the responsible movement of live aquatic animals is provided in the FAO Technical Guidelines for Responsible Fisheries (FAO, 2007b).
Zoning is an important element of a National Aquatic Animal Health Strategy (NAAHS), a broad yet comprehensive strategy to build and enhance capacity for the management of national aquatic biosecurity and aquatic animal health. It contains the national action plans at the short-, medium- and long-term using phased implementation based on national needs and priorities; outlines the programmes and projects that will assist in developing a national approach to overall management of aquatic animal health; and includes an Implementation Plan that identifies the activities that must be accomplished by government, academia and the private sector. It cannot be implemented in isolation and is interlinked with other elements of a NAAHS (FAO, 2007b).
A number of other codes and conventions contribute to standardization of international protocols and responsibilities (Håstein et al., 2008). These include:
• International Council for the Exploration of the Sea (ICES) Code of Practice on the Introductions and Transfers of Marine Organisms;
• International Maritime Organization Guidelines for the Control and Management of Ships’ Ballast Water to Minimize the Transfer of Harmful Aquatic Organisms and Pathogens;
• International Union for the Conservation of Nature Guide to Designing Legal and Institutional Frameworks on Alien Invasive Species;
• European Inland Fisheries Advisory Commission (EIFAC) Codes of Practice and Manual of Procedures for Consideration of Introductions and Transfers of Marine and Freshwater Organisms; and the
• WTO Convention on Biological Diversity.

4. Purpose of zoning

Zones make distinctions between populations of aquatic animals depending on respective disease prevalence.
Zones are therefore used to manage and control the spread of contagious aquatic animal diseases. By establishing zones of known disease status, control measures can be implemented, disease prevalence can be established, and intensity of surveillance can be determined. Zones should not be proposed as administrative regions based on production-related needs or convenience (Corsin et al., 2009).
Zoning is an important procedure for disease control and eradication, and for maintaining international trade opportunities, and control measures should be under the direct control of a competent authority (Zepeda, Jones and Zagmutt, 2008). Where a particular aquatic animal disease posing international risk is present in only part of a country, the establishment and preservation of disease-free zones may allow declarations of freedom from disease, thereby ensuring safe trade from such zones. To provide such declarations, the specified subpopulations of aquatic animals within a zone must become the target of surveillance (Corsin et al., 2009). The identification and traceability of subpopulations within a zone must be clearly defined, and the procedures used to establish and maintain a distinct health status of a zone must be appropriate to the disease, taking into account the epidemiology of the relevant disease, environmental factors, risk of introduction, and establishment of disease and applicable biosecurity measures (OIE, 2016). Disease-specific recommendations for OIE-listed diseases are provided in the OIE Manual of Diagnostic Tests for Aquatic Animals (OIE, 2015). Relevant guarantees applicable to a disease-free declaration, as often required by importing countries, depend on the ability of the exporting country to demonstrate that one or more zones within a country or region do not harbour infected animals and can be kept safe from transfer of the disease from potentially infected zones.