Marking a milestone
Strong commitment from industry and academics to address remaining wrasse bottlenecks
THE University of Stirling held a workshop on May 23 to mark the completion of its four-year research project into ballan wrasse. Led by the university’s Institute of Aquaculture (IoA), and co-funded by the Scottish Aquaculture Innovation Centre (SAIC) and industry partners Mowi, Scottish Sea Farms and BioMar, the project aimed to address knowledge gaps in ballan wrasse biology and fast track domestication of the species.
The project brought together scientists from the IoA, 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 the Stirling Court Hotel on the Stirling campus, bringing together 50 representatives from across the Scottish and Norwegian academic and salmon farming sector.
During the project, there were contributions from a wide range of collaborators, including Otter Ferry Seafish, Cefas, Ridgeways Biologicals, HTI Hydroacoustic Technology and the Norwegian Veterinary Institute.
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 Sea Farms at Machrihanish.
As with any new marine finfish species, many hurdles had to be overcome to make the farming of the species commercially feasible.
The workshop consisted of a series of presentations and discussions from project scientists and industry partners, summarising the main find
ings 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 said: ‘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-project leader 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 make-up 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, who 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 feeds, commercialised by BioMar.
The next session focused on health challenges and management, with presentations from Stirling PhD student Athina Papadopoulou and Dr Gustavo Ramirez from Ridgeway Biologicals.
Results highlighted 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
“There is a clear urgency in producing the numbers required”
been implemented by 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’s cleaner fish manager.
Results on behaviour post deployment obtained through the use of hydro-acoustic 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.
These sessions showed the very significant progress made by the consortium, but also highlighted knowledge gaps that remain and which will require further research.
Davie said:‘While key milestones have been achieved in the farming of ballan wrasse, cleaner fish are still in the research and development phase and more research is required to upscale production and meet industry requirements for farmed, robust and effective ballan wrasse.
‘There is a clear urgency in producing the numbers required; however; it must be acknowledged that we are only five years since the first spawning events in captivity in Scotland.’
An industry perspective was then given by Dr Ralph Bickerdike, head of Fish Health and Technical at Scottish Sea Farms, and Dougie Hunter, head of Cleaner Fish 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: Espen Grøtan, Mowi biological manager of ballan wrasse production: Dr Ingrid Lein from Nofima; and Dr Duncan Colquhoun from the Norwegian Veterinary Institute.
Grøtan 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.
Lein presented an overview of Nofima’s research activities on cleaner fish, with an emphasis on welfare in production and cages, while Colquhoun gave a comprehensive review of the many health challenges identified and researched in cleaner fish.
Collaboration with colleagues in Norway will continue to ensure the two countries complement each other rather than overlap efforts.
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.
‘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.’
For further details on cleaner fish research, contact Professor Herve Migaud (hm7@stir.ac.uk) or Dr Andrew Davie (ad8@stir.ac.uk).