Biosecurity in Aquaculture: What are the Measures Designed to Prevent Diseases in Fish Farming?

Aquatic animal species are in constant interaction with potential pathogens that can strongly impair growth performance and result in significant economic losses for livestock production. Although the risk of contamination cannot be eliminated it can be limited substantially by taking appropriate precautions. What are the biosecurity prerequisites to implement in farms for reducing contamination?

Biosecurity is key to productive aquaculture systems

Biosecurity encompasses all measures designed to prevent diseases from occurring and from spreading by isolating, as much as possible, animal farm populations from external contamination. Recurring or prolonged contact with external environments (water, sediment, wildlife) favors the development of new diseases. For this reason, non-recirculated aquaculture systems are more difficult to isolate than closed water circuits.

The first level of biosafety relates to the choice of farm location. Once the farm facilities have been installed, it is very difficult to change the quality of water inlet. Thus, it is absolutely necessary to have prior knowledge of the farming and industrial activities - livestock as well as crop production – that are conducted upstream of the farm, especially if the water used originates from a stream. Depending on the results of these investigations, the treatment system for incoming water must be adjusted accordingly.

What are the main biosecurity measures allowing for satisfactory growth performance in fish farming?

On a daily basis, it is necessary to pay attention to the risk factors likely to occur in the  various phases of rearing, as follows:

• The quality of inputs: whether they are animals (eggs, larvae, juveniles...) or supplies (food, veterinary products...), it is essential to check the quality of  all  resources that are used in the farm.
•  The quality of incoming water: this is a more or less controllable variable depending on the rearing system that is applied. After all aspects of the pre-installation phase have been checked, the water must then be sampled periodically.This is a key parameter that needs to be monitored and assessed on an ongoing basis.
• The disinfection of vehicles accessing the farm: it is common for drivers of vehicles entering a farm to circulate in between several fish farms as they are likely to be veterinarians, feed manufacturers, fish transporter, etc. To this end, wheel dips can be used for better desinfection of cars.
• The disinfection of equipment used in handling fish: precautionary measures related to pathogens must be applied to all production units - ponds, cages, ponds or aquarium - within each farm. Therefore, the transfers of equipment from pond to pond must be spaced out as much as possible, especially when it comes to the transfers of nets, which are the most likely tools to be directly in contact with animals.
• Employee hygiene within the farm: farm workers must regularly wash their hands; this rule especially applies to those who manipulate animals through sorting, vaccination, feeding... Hydro-alcoholic solutions have proved efficient and easy to handle to this end. In addition, all employees must have their shoes thoroughly decontaminated. In this respect, placing footbaths and brushes at the entrance of each livestock compartment can help limit the spread of pathogens. Keeping a regularly updated register of visits also constitutes an important component of the protection process. 
• The manipulation of dead and/or moribund animals: since dead animals are particularly likely to be contagious, their carcasses should be handled with care so the pathogens they contain will not spread. It is also of the utmost importance to isolate and destroy these carcasses soon after death has occurred.
• The reduction of the stress level in animals: limiting animals’ stress can favor improved performance. Furthermore, stress has physiological repercussions leading to the spread of diseases in livestock.

These guidelines constitute a first line of sanitary measures in aquaculture. However these are far from being exhaustive and can be tailored to the needs of each farm depending on its characteristics.

The TECHNA Group assists both feed manufacturers and fish and shrimp breeders willing to implement new ways to improve biosecurity and ensure optimal growth performance in their farms. For more information, please do not hesitate to ask our experts at the TECHNA Group!