6.9 Role of the Private Sector

Official aquatic animal health services provided by state veterinarians and technologists encompass the surveillance and regulatory aspects of aquatic disease management.

The provision of aquatic veterinary services is a specialized field, as is the provision of official regulatory services, and effective biosecurity management in some instances requires both official and private-sector expertise (Palic´, Scarfe and Walster, 2015). To ensure effective management of aquatic biosecurity, aquaculture farmers should be encouraged to make use of both private and official aquatic animal health services.
In countries with limited resources or where official aquatic animal health services are poorly developed, private-sector aquatic animal health specialists can play an important role in supporting the competent authorities tasked with biosecurity zoning. By applying sound biosecurity plans to compartments and zones within a country, private-sector specialists are able to provide a significant advantage to aquaculture farmers while at the same time creating a favourable environment for third party or official auditing and certification. Farmers need to realize that disease and infectious hazards change and evolve over time. An effective biosecurity plan needs to be regularly revised to remain up to date with relevant diseases and to remove procedures that may have become obsolete. Unless the official veterinary services of a country have the expertise and capacity to provide this service, aquaculture farmers should make provision to fund private-sector specialists to assist with the task.

 

 

Application of Zoning and Compartmentalization

Zoning and compartmentalization are an integral part of biosecurity measures implemented by countries and aquaculture industries to contain, control and eradicate contagious diseases. They can be applied in many facets, but the implementation requires development of appropriate diagnostic, surveillance and reporting capabilities within a specific regulatory framework (FAO, 2007b). In the case of an outbreak or suspicion of an outbreak of a disease for which control measures are in place, zones or compartments define the geographic area to which restrictions to the movement of aquatic animals and other control measures are applied. Within the framework of zoning and compartmentalization, certification of disease status and freedom from specific pathogens provide further measures to prevent spread of disease (Håstein et al., 2008). Where eradication is not possible or practical, containment and control within zones provides an alternative means of limiting the impact of a disease (FAO, 2007b). Establishment of free zones, based on ecological, geographical, hydrological and climatological barriers and meeting the specific technical requirements for disease control, as defined by the OIE Aquatic Animal Health Code (OIE, 2016), will restrict the impact of disease to infected zones and allow unhampered movement of aquatic animals from free zones.
Effective management of zones requires that animals may be moved only from zones where the same or fewer pathogens are present than in the receiving zone, or between zones where none of the specified diseases occur. Restrictions are justified to prevent movement from zones where diseases occur that are absent from the receiving zone (FAO, 2007b). Where zones based on entire river systems and coastal areas involving more than one country are affected by a contagious disease, neighbouring countries will benefit from regional zoning (FAO, 2007b).
In the case of salmonids, the breeding cycle of rainbow trout in the Northern Hemisphere is offset by six months from that of the Southern Hemisphere. South Africa, for example, has a salmonid industry that dates back to early colonial days, and trout hatcheries have traded in live salmonid ova with the Northern Hemisphere for many decades, culminating with the annual export of over 40 million eyed ova during the latter part of the last century. As the breeding cycle of salmonids in the Southern Hemisphere is six months apart from that of the Northern Hemisphere, it is beneficial for farmers in both hemispheres to supplement their production through an additional stocking of young fish during the time of year when in the respective hemisphere hatchery stock would be unavailable.
Trout farmers in South Africa, to this day, import their so-called summer eggs from Northern Hemisphere farms, and the Northern Hemisphere provides a good market for ova produced in the Southern Hemisphere.
South Africa has had effective legislation governing the introduction of exotic salmonid diseases. The importation of eyed salmonid ova is only permitted where guarantees of freedom from specific salmonid diseases can be provided by the authorities of the exporting country. As an additional measure, official sampling of imported ova takes place at the port of entry. Such imports remain under quarantine and are traceable until the results of the testing have become available.
Over this long time span, serious salmonid diseases have not been introduced into South Africa despite the frequent importation of eyed salmonid ova.
The production of SPF trout ova for international trade provides an example of the implementation of the concept of compartmentalization. South Africa, for example, has no national surveillance data on the prevalence of OIE-listed salmonid diseases. Yet a number of rainbow trout hatcheries in this country are registered as export hatcheries with the country’s competent authority. Export hatcheries, managed as a compartment, need to comply with biosecurity measures reflecting the requirements of the importing country and stipulated by the relevant competent authority tasked with issuing the disease-status guarantees for export. In this manner, relevant disease-status guarantees that meet the requirements of importing countries can be provided by the competent authority allowing export of salmonid ova from South Africa to countries such as those in the European Union.
For a competent authority of a country to provide guarantees of freedom from specific diseases, the source population of aquatic animals needs to be subjected to disease surveillance testing. Such testing must be done at a statistically relevant level of confidence. The OIE recommends working at the statistical 95 percent confidence level of detecting a disease agent with a prevalence of 2 percent or lower (OIE, 2016). This principle has been applied to trout hatcheries exporting ova. In the case of South Africa, depending on the relevant province, implementation of the farm biosecurity plan and collection of surveillance samples is done either by a state veterinarian with aquatic animal disease knowledge or jointly by a state veterinarian and a private-sector aquatic animal health specialist appointed by the hatchery owner. The laboratory testing of the samples is performed by an accredited national laboratory. Provided the hatchery has been approved by and is registered by the competent authority, the issuing of export certificates reflecting disease-status guarantees is done by the state veterinarian responsible for the hatchery.
The koi industry in South Africa has been affected by koi herpesvirus with frequent outbreaks among the koi collections of hobbyists and farmers since 1998.
Most of these go unreported. As South Africa has no official surveillance data on either koi herpesvirus (KHV) or rhabdovirus carpio, the causative agent of spring viraemia of carp (SVC), koi producers wishing to export fish to certain international markets need to provide SPF certification to meet the requirements of the importing country. Koi farms based on protected water supplies and conforming to the requirements for registration of export farms can be managed as a compartment in order to export SPF fish (Huchzermeyer and Colly, 2015). Such farms need to maintain a closed population of fish, with introductions being allowed only from sources with a certified disease-free status of equivalent or higher standard. The fish population on such a farm is subjected to a statistically valid level of testing for KHV and rhabdovirus carpio for a mandatory of four tests at six-month intervals (OIE, 2016).
After the initial two-year testing period, the competent authority is able to issue guarantees of freedom from KHV and SVC, and fish can be exported. In the absence of wider surveillance, and establishment of KHV and SVC free zones, the routine of six-month testing continues as long as a farm remains registered as an export facility and continues selling SPF fish. As in the case of trout export hatcheries, both the state veterinarian and a private-sector aquatic animal health specialist jointly implement, maintain and monitor the biosecurity measures relevant to the conditions for approval and registration of an export fish farm. In the case of koi, the private-sector specialist is responsible for collection of surveillance samples. The accredited national laboratory in South Africa is only able to test for SVC, and a private-sector accredited laboratory is used for analysing the KHV samples. Provided all tests are negative and all the conditions of the importing country have been met, the relevant state veterinarian will issue the disease status guarantees.