In recent years the increased prevalence of chemotherapeutant resistance in salmon lice has led to dramatic changes in lice management in the Norwegian aquaculture industry. Use of cleaner fish for biocontrol of salmon lice has increased significantly over the last three years in all regions from Rogaland to Nordland. According to the FHL webside www.lusedata.no,  40% of all Norwegian salmon localities use cleaner fish as part of their louse control strategy.

The most common fish currently in use are wild-caught goldsinney,-ballan-, and corkwing wrasse. An estimated 16 million wrasse were captured for this purpose in 2010. Farming of ballan wrasse and lumpsucker remain in the pioneer phase. There is a huge requirement for knowledge relating to health management in cleaner fish species, in particular there is a need for identification and characterisation of the main diseases affecting these fish. Only when the main diseases are identified can preventative and ameliorating measures, including vaccination, be developed and introduced.

The main current causes of death in cleaner fish are related to bacterial diseases. This situation mirrors the pioneer phases of both salmon and cod aquaculture in which, prior to development of effective vaccines, bacterial diseases comprised the main threats to the industry. Antibiotic treatment of diseased wrasse within a cage of healthy salmon is not an option. Directed development of vaccines against the most serious of the infectious diseases will constitute one of the main pillars of sustainable cleaner fish use, both farmed and wild-caught.

The Norwegian Veterinary Institute is uniquely strategically placed to identify and gather bacterial isolates recovered in the course of the diagnostic service provided by the institute to the Norwegian aquaculture industry.

Although a number of bacteria with pathogenic potential have been isolated from farmed and wild caught cleaner fish including such species as Vibrio anguillarum, V. ordalii and Pseudomonas anguilliseptica, there are indications that the (current) primary pathogens of cleaner fish are Aeromonas salmonicida, V. splendidus and V. tapetis. However, although commonly isolated from diseased and dying cleaner fish, the pathogenic potential and the antigenic diversity amongst these bacterial species has not been confirmed or investigated.

As the knowledge base for cleaner fish bacteriology is small, the project must take a broad approach. The present project will, therefore concentrate on surveying the infection status of wild and farmed cleaner fish, investigate the role of the current three major bacterial suspects yet remain open for characterisation of relevant novel species identified during the project. 

Research partners

• Vaxxinova Norway AS
• Norges forskningsråd
• Norges Veterinærhøgskole