Biosecurity in Aquaculture Part III: Producers level

By Leonardo Galli, Don Griffiths, Pikul Jiravanichpaisal, Nattawadee Wattanapongchart, Oranun Wongsrirattanakul and Andrew Shinn

In this final part, the focus will be on the producer, i.e. on biosecurity measures that could be implemented within hatcheries and farms. Due to the immense variation in infrastructure and system design between the two types of production unit, it is not possible to define one precise biosecurity plan that fits all. Instead, the following provides a series of general guidelines that can be adapted to each circumstance.

Biosecurity at the level of producers

In order to get the benefits of a biosecurity plan, biosecurity should be looked upon as part of the overall management system. This means that many aspects of the production pipeline must be taken into consideration, which will include:

  1. broodstock source, quality and management;
  2. larvae (post-larvae) quality;
  3. stocking densities;
  4. feed and feeding regimes;
  5. hatchery disinfection and management;
  6. pond/system preparation;
  7. monitoring of water and soil parameters;
  8. disease surveillance;
  9. training and record keeping, etc.

Here we take a closer look at four critical steps that should be considered in establishing a comprehensive biosecurity program.

Infrastructure

The infrastructure is an important component in any biosecurity plan. Ideally the land surrounding the production unit should be fenced which may be easier for hatchery units and small farms but may not be achievable for larger farm sites. Fencing is used to prevent the entry of wild animals and to deter unauthorised personnel from gaining access to the facilities. The layout of the facility must be planned in such a way so as to minimise cross contamination among different sections. In hatcheries, for example, it is helpful to have a footbath (with an appropriate disinfectant that is changed on a regular basis) and hand disinfectant containers at the entrance of each room. Each unit should have its own equipment, i.e. buckets, jars, etc, and these must be properly identified and should not be removed for use in other areas.

Both the incoming and outgoing water should be treated to minimise pathogen introduction. This should be the case for the incoming water supply, and also for the discharged water to prevent pathogen introduction via effluent water into local watercourses. The use of a recirculating water system, with an appropriate integral water treatment/management system, can be an effective means of reducing the risk of pathogen introduction into production areas. Investing in a spare set of hatchery water supply pipes, which can be changed and sterilised allows hatcheries to disinfect effectively while minimising the idle time when a hatchery is not producing seed.

A well designed system for the culture of livestock can allow for the isolation of part of the system to be disinfected or treated (in the case of a disease event) without the need for a total shut down in production.

Image of Tilapia Namsai farm
Between hatcheries and farms there is immense variation in infrastructure and system design and although it is not possible to define one precise biosecurity plan that fits all, how biosecurity at the producers’ level can be achieved will be discussed in the third article in this series.

Biosecurity protocols

Written standard operating procedures (SOPs) must be in place before defining biosecurity procedures. A procedure similar to the Hazard Analysis and Critical Control Points (HACCP) can be used to elaborate the biosecurity protocol. The first step is to prepare a production flow diagram (i.e. the movement of animals, water, fresh food and personnel through the on-site systems) and then to identify where there are potential risks of pathogen introduction. Generally, the main source of pathogens is via aquatic animals such as larvae, post larvae, broodstock, insects, water, fresh and live food (e.g. larval feeds, polychaetes, fish etc) and the personnel managing operations. Once the critical control points where pathogen introduction may occur have been identified, it is then possible to establish acceptable limits (i.e. what are the maximum number of pathogens acceptable at each point), to establish a control system (i.e. which mechanisms will be used to detect and quantify the pathogen), to establish corrective actions (i.e. what to do once the predetermined pathogen threshold levels have been reached), and, to maintain a sufficiently detailed record of activities so that the impact of corrective management actions can be assessed and refined as necessary.

When defining a protocol, it should be as specific as possible. If, for example, a disinfectant or a medicant is being used, then it is vital that the protocol specifies the dosage, the duration of application and the regime. For each activity where a risk has been identified, there should be a log that details the name of the person responsible for the job, the date, the time of execution and any observations that were made. Once the protocol is finished and approved, this must then be communicated to the entire team, including security guards, kitchen personnel, maintenance staff, gardeners, etc. The workers must sign the document confirming their participation in the communication meeting to demonstrate that they understand the new protocol and will comply. These protocols, however, should be regarded as “flexible” documents that can be refined and updated whenever needed. It is important that whenever a procedure is revised and updated, it will be communicated to all personnel.

Health surveillance

Image of a health check in progress
Regular health checks to monitor and control the sanitary status of all aquatic livestock on site is critical.

The third critical step within a comprehensive biosecurity program revolves around a health surveillance system which regularly monitors and controls the sanitary status of all aquatic livestock on site. Likewise, the surveillance system should be clearly defined and appropriately detailed so that it can be followed without ambiguity. The surveillance system that is used can range from a simple visual observation of the stock to the assessment of aquatic livestock samples and tissues using a sophisticated battery of laboratory techniques, including histology and PCR. This will depend on the capacities of each laboratory establishment. The frequency of monitoring and the analyses to be carried out should also be defined and all the results recorded in a farm health log. A traceability system, i.e. of feed, treatment products and, specifically, of all stock movements on, off and around the site, must be in place.

Technical qualifications

The fourth key step is that the managers and technicians responsible for production operations should have sufficient experience, training and knowledge to be able to properly guide those working under them. Periodic meetings with site personnel should be organised by the person responsible for each section, in order to refresh procedures, to ensure effective knowledge exchange and to uphold proficiency in husbandry. Underpinning each of these recommended steps is the responsibility of the site personnel. The effectiveness of a biosecurity plan may be measured through the absence of disease and mortality events, while its success is based in effective training, communication, proficiency and compliance. Staff bonus schemes can be used to incentivise effective implementation of the hatchery and farm health plans and biosecurity protocols.

The authors are from Fish Vet Group Asia Limited, Bangkok, Thailand.

Leonardo Galli is technical director, a veterinarian, histopathologist,molecular biologist and shrimp expert.

Don Griffiths is operations director and has extensive expertise in Asian aquaculture Pikul Jiravanichpaisal is a senior scientist and shrimp health expert specialising in microbiology, histopathology and immunology

Nattawadee Wattanapongchart is business administration and marketing manager Oranun Wongsrirattanakul is a laboratory assistant, specialising in histology and molecular biology Wimonthip Jarupheng is business administration assistant

Andrew Shinn is a senior scientist and an aquatic parasitologist specialising in product development.

For more information on this article contact info.FVGAL@fishvetgroup.com

Read part 1 of this series: International considerations and part 2: National considerations.