International workshop on ballan wrasse research project

The University of Stirling has led a four year research project co-funded by the Scottish Aquaculture Innovation Centre (SAIC) and industry partners MOWI, Scottish Seafarms and BioMar to address knowledge gaps in ballan wrasse biology and fast track domestication of the species.

Group photo of attendees at science workshop

During the project, a wide range of collaborators also contributed to the project including Otter Ferry Seafish, CEFAS, Ridgeways Biologicals, HTI Hydroacoustic Technology and the Norwegian Veterinary Institute. The project brought together scientists from the Institute of Aquaculture working on broodstock management, nutrition, health and behaviour to develop tools and protocols for the farming of cleaner fish in Scotland. Results from the project were presented at a workshop on 23 May at the Stirling Court hotel on University of Stirling campus bringing together 50 representatives from across the Scottish and Norwegian academic and salmon farming sector.

Sea lice are naturally occurring crustacean ectoparasites of salmon that continue to be one of the most costly and challenging fish health issues for the salmon farming industry. The cohabitation of cultured native cleaner species with salmon stocks is widely considered to be a key element of integrated pest management control. Ballan wrasse and Lumpfish are the two species being actively farmed by the sector but both are very new in terms of production experience. Research and development of ballan wrasse farming in the UK was initiated in 2010 by scientists at the Institute of Aquaculture together with the joint venture between MOWI (formerly Marine Harvest Scotland) and Scottish Seafarms at Machrihanish. As for any new marine finfish species, many hurdles had to be addressed to make the farming of the species commercially feasible.

The workshop on the 23rd of May marked the completion of the most recent project on the species and consisted in a series of presentations and discussions from project scientists and industry partners summarizing the main findings and tools developed for broodstock and genetic management, nutritional and environmental requirements, health management and deployment. A welcome and introduction was given by Herve Migaud, the project leader who commented “The project made significant breakthroughs in the domestication and understanding of the requirements of the species and knowledge has been directly implemented into the industry. The aim of the workshop was to disseminate project results, openly discuss experience across all Scottish salmon farmers and discuss next steps going forward.”

Dr. Andrew Davie (co-PI of the project at Stirling) then gave an overview of the main findings and tools developed for the species broodstock management. One of the highlights for the project was the successful closing of the lifecycle in 2017, with spawning of first F1 generation at the Machrihanish hatchery, marking a critical milestone in ballan wrasse farming and the first step towards genetic improvement. Many tools were also developed to assess and control the genetic makeup of the broodstock, enhance egg productivity and quality and control gender. This was followed by a presentation from Thomas Cavrois, PhD student at the Institute of Aquaculture, and Dr. Antonios Chalaris from BioMar. They summarised how the project research has led to a better understanding of ballan wrasse nutritional requirements and digestive physiology especially in relation to the optimisation of culture conditions for post weaned juveniles. The research has demonstrated how the hatchery production window can be reduced significantly through effective environmental management in conjunction with new commercial feeds commercialised by Biomar.

The next session was focused on health challenges and management with presentations from Stirling PhD student Athina Papadopoulou and Dr. Gustavo Ramirez from Ridgeway Biologicals. Results highlight included the identification of the main bacterial challenges in the species, the characterisation of Atypical Aeromonas salmonicida and the development of an effective autogenous vaccine which has subsequently been implemented in the Scottish industry. Last but not least, advances made on deployment of ballan wrasse to salmon cages were presented by Dr. Adam Brooker from the Stirling team and Ronnie Hawkins, MOWI cleanerfish manager. Results on behavior post deployment obtained through the use of hydroacoustic tracking were presented strongly demonstrating the need for acclimatisation of the farmed wrasse prior to their release in the pens. In addition, many advances were made with the design of suitable hides, feeding systems and overall wrasse management in cages. Overall, these sessions showed the very significant progress made by the consortium but also highlighted knowledge gaps that remain which will require further research.

Andrew Davie commented “While key milestones have been achieved in the farming of Ballan wrasse, cleaner fish is still in the research and development phase and more research is required to up-scale production and meet industry requirements for farmed, robust and effective ballan wrasse.” He added “There is a clear urgency in producing the numbers required, however it must be acknowledged that we are only 5 years since the first spawning events in captivity in Scotland.”

An industry perspective was then given by Dr. Ralph Bickerdike, Head of Fish Health & Technical at Scottish Seafarms and Dougie Hunter, Head of Cleanerfish and Technical at MOWI. They both presented their respective company strategies and reiterated their strong commitment to cleaner fish farming in the future. This was followed by three presentations from colleagues invited from Norway, first Espen Grøtan, MOWI Biological manager Ballan wrasse production, Dr. Ingrid Lein from NOFIMA and Dr. Duncan Colquhoun from the Norwegian Veterinary Institute. Espen gave an overview of the advances and challenges faced during the hatchery phase in Norway as well as highlighting the planned expansion in ballan wrasse production capacity. Ingrid presented an overview of research activities at NOFIMA on cleaner fish with an emphasis on welfare in production and cages while Duncan gave a very comprehensive review of the many health challenges identified and researched in cleaner fish. Collaboration with colleagues in Norway will continue to ensure we complement each other rather than overlapping on research efforts.

Herve Migaud concluded “This has been a very successful project and workshop, which celebrated the significant achievements that have been realised but equally clearly identified the direction for future work. Thanks to all partners, students and Stirling colleagues for their hard work.”

He added “Throughout the workshop it was clear that there is a very strong commitment from both the industry and academic community to address remaining bottlenecks which will ultimately ensure the effective and widespread implementation of farmed ballan wrasse in Scotland is realised to control sea lice. Coming years will see the upscaling of this innovative pest management strategy contributing to make the salmon industry more resilient.”

Further information

For further details on cleaner fish research, please contact Professor Herve Migaud ( or Dr. Andrew Davie (