Scaling up production and implementation of farmed cleaner fish

This collaboration has proven to be a landmark in the development of farmed ballan wrasse, not just in Scotland but globally. The discoveries made and new knowledge gained have significantly advanced our understanding of many of the fundamental areas of fish welfare and biological control of sea lice, and in doing so will help pave the way for successfully scaling up wrasse production. – Ralph Bickerdike, Head of Fish Health & Welfare, Scottish Sea Farms

Ralph Bickerdike, Head of Fish Health & Welfare, Scottish Sea Farms

The project provided new knowledge that has been directly applied to the development of wrasse-specific hatchery and post-deployment feeds – Patrick Campbell, MD of BioMar UK and Vice President Salmon of BioMar Group

Patrick Campbell, MD of BioMar UK and Vice President Salmon of BioMar Group

The project has brought a plethora of results that can ultimately be used within the production hatcheries to improve fish health and welfare. Techniques developed by the various researchers in association with farm staff will improve fish husbandry and allow further innovation under production conditions – Dougie Hunter, Technical Director, Mowi Scotland

Dougie Hunter, Technical Director, Mowi Scotland

Impact

The project was very successful and fully achieved its goals. Scaling up the production of Ballan wrasse mainly focussed on developing the rearing processes for this species to increase production but also acclimatise farmed Ballan wrasse for effective delousing. Seven processes were developed or optimised:

• Sex induction to provide males
• New vaccine and efficacy confirmed
• Genetic marker panel for genotyping
• Egg management by degumming and disinfecting
• Deployment protocols for natural behaviour with diurnal rhythmicity
• Enhanced live feed enrichments
• Husbandry conditions for enhanced growth performances

Parental assignment developed as a service that will allow the genetic improvement of the species through selective breeding. Two products were improved:

• Further validation of wrasse feed blocks developed by Stirling academics
• Wrasse hides and furnishings.

During the project first generation (F1) broodstock were bred in captivity, which is a world first for the species. This opens many possibilities for the future, especially the improvement of the species traits by selection. The project was awarded the Applied Research Award at the Aquaculture Awards 2019.

Speaking on the value of the project to the academic team, Prof. Herve Migaud said: “This project helped IoA scientists involved to become and remain the leading scientists working on cleaner fish research and overall on integrated sea lice pest management strategies and work closely with the leading salmon industry partners in the UK.”

Three PhD projects and ten MSc theses were authored as part of this project by students at the Institute of Aquaculture, University of Stirling.

Reporting on the project’s legacy, Dougie Hunter, Technical Director at Mowi Scotland, said: “The project has brought a plethora of results that can ultimately be used within the production hatcheries to improve fish health and welfare. Techniques developed by the various researchers in association with farm staff will improve fish husbandry and allow further innovation under production conditions.”

Ballan wrasse is a type of ‘cleaner fish’ which eats naturally occurring marine parasites, such as sea lice, from salmon. The majority of wrasse used in this way has been sourced from the wild in accordance with the guidelines from Marine Scotland, RSPCA Assured and local fishery boards. The aim of this project was to develop an aquaculture system for Ballan Wrasse in order to provide a sustainable stock.

The natural lifecycle of wrasse is six years and over this time, the project team bred wild-caught wrasse, raising the offspring from egg to adults of reproductive age. These offspring have now produced their own eggs and successfully hatched, the first fully farmed lifecycle of wrasse in a controlled environment.

This has provided a proven, repeatable procedure for breeding, weaning and rearing wrasse and will lead to a reduced reliance on wild stock.