Use of Ballan wrasse (Labrusbergylta) as a cleaner fish for the biological control of sea lice on farmed salmon

Description: A series of trials will be conducted to examine the feeding behaviour of Ballan wrasse and to test the efficacy ofBallan wrasse in removing lice. These trials will take place in the NAFC trials site, which consists in twelve cages measuring 6x6 each one. There are two blocks with six cages per block.

• Feeding trial: Will try to determine the preferred diet for Ballan wrasse, and how different diets impact condition. This trial started on 20/08/2010 and will run for three months. The three different diets tested are:
  o Mussels
  o Salmon pellets
  o Mussels and salmon pellets
• Efficacy trial: Six cages stocked with 3500 salmon smolts. Stock numbers are spread evenly over the cages to ensure uniformity before the commencement of experimental work. Wild caught Ballan wrasse will be introduced initially at a rate of 2% of salmon stock levels into four of the salmon stocked cages. The other two control cages will not contain any Ballan wrasse.  Habitats will be provided for the wrasse in the form of open prawn pots.
  
  Stocking levels to be investigated over the trial.

Start date and duration: The project began on May 2010 and will run for two years.

Objectives:

• To gain an understanding of the history and future potential for using cleaner-fish technology in the salmon industry in the UK
• Establish the current legislative, management and perception issues when using cleaner-fish in commercial salmon production
• Establish the optimum cleaner-fish to salmon stocking density for maximum efficacy. 
• The development of cleaner-fish management protocols and simple methods of monitoring their welfare.
• Understand the cost / benefits of adopting cleaner fish technology
• Reporting and Dissemination

Outputs

• A report of operational welfare indices being utilised by the aquaculture industry
• A report on current industry, market and consumer perceptions of cleaner-fish technology
• Finalised trial protocols and sampling methodologies
• Efficacy, welfare and environmental data collection and analysis
• A photographic sea lice key
• Guidelines on operational welfare indices for cleaner-fish
• Report on the business case for using wrasse industry workshops and presentation
• Final Report

Partners: Shetland Aquaculture, NAFC Marine Centre and KTP. The partnership received financial support from the Knowledge Transfer Partnerships programme (KTP).  KTP aims to help businesses to improve their competitiveness and productivity through the better use of knowledge, technology and skills that reside within the UK Knowledge Base.  KTP is funded by the Technology Strategy Board along with the other government funding organisations.