Introduction to Fish Farm Biosecurity
The intensification of fish production provides an ideal environment in which disease-causing organisms can flourish and cause serious damage to productivity. Disease may come from any number of sources, for example, viruses and bacteria. However it originates; it spreads through recognised vectors of infection. These include fish stocks, staff and visitors, equipment, vehicles and transportation, other aquatic life, birds and animals, the aquatic environment and even the air itself.
Medication and vaccination have traditionally played a major role in treating diseases but it is now widely accepted that they cannot, in isolation, prevent losses due to disease. Modern farming demands a holistic approach. Unless the background challenge from disease-causing organisms can be controlled, and good management practices strictly followed, medication and vaccination alone are not capable of adequately protecting fish stocks.
Fish must be given an environment in which the level of infection is controlled to the point where vaccination and medication can achieve beneficial effects. Biosecurity is the key to achieving this.
Biosecurity involves the exclusion of disease-causing organisms from the environment. This is particularly important in fish production. It is achieved by the use of external and internal biosecurity barriers:
- External Barriers – blocking the spread of disease onto and off of a fish farm
- Internal Barriers – blocking the spread of disease within the fish farm
The correct use and selection of disinfectants is very important and ensures that pathogen challenge is minimised, maximising the fish’s natural defence against infection.
Not all disinfectants are effective against the wide range of viral and bacterial disease-causing organisms that affect fish production. Even disinfectants with similar chemistry can have widely different spectra of activity and effective dilution rates. Selecting a disinfectant is therefore very important. The disinfectant must have independently proven efficacy against a wide range of aquaculture pathogens and be effective at low temperatures.