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Better disease protection for salmon pen cleaner fish

Farmed ballan wrasse are increasingly being used for lice control in salmon pens.
Farmed ballan wrasse are increasingly being used for lice control in salmon pens.

A research consortium is working to optimise the formulation and delivery of a key vaccination given to protect the cleaner fish species ballan wrasse from disease.

The consortium, led by the University of Stirling’s Institute of Aquaculture (IoA) and salmon farmer Mowi Scotland, will explore the range of factors that determine the best possible conditions for delivering vaccinations against Aeromonas salmonicida, a bacterium which can cause potentially fatal outbreaks of disease in cleaner fish.

Ballan wrasse currently receive vaccinations against multiple health conditions at the hatchery stage. However, the group – which also includes wrasse farmer Otter Ferry Seafish, Ceva Ridgeway Biologicals and the Sustainable Aquaculture Innovation Centre (SAIC) - will look at alternative formulations of the vaccine that could offer greater protection.

Immersion delivery

A core aim of the project is to determine the most effective composition of antigens to elicit the best immune response in juvenile fish. 

The team will also consider the best timing and method of delivering the vaccine - ideally through immersion which can be easier to administer than injections - and assess and compare the way ballan wrasse react to each variable.

Sean Monaghan:
Sean Monaghan: "Prevention is better than cure."

Dr Sean Monaghan from the IoA said: “Enhancing vaccines for Aeromonas salmonicida could represent a significant step forward in the use of ballan wrasse in aquaculture.

“We know that prevention is better than cure and we are, therefore, working towards the development of more effective vaccine formulations and protocols that can be used by hatcheries and producers to improve fish welfare.”

Excellent cleaners

Mowi is growing large numbers of wrasse at its cleaner fish hatchery in Anglesey, helping the salmon farming sector move away from a reliance on wild-caught wrasse for eating sea lice off farmed salmon.

Dougie Hunter, technical director at Mowi, said: “Ballan wrasse alongside lumpfish are excellent cleaner fish and a natural solution to effectively manage sea lice on our salmon.

“For us to give these fish the best environment and welfare, we must protect them again stress and disease, including infection caused by Aeromonas salmonicida, which can be observed in wrasse from an early stage.”

SAIC chief executive Heather Jones said: “Ballan wrasse are a core element of our sector-wide efforts to sustainably tackle the challenge of sea lice and vaccinating them against disease is essential for long- term success. This latest project adds to the range of valuable collaboration projects exploring best practice for cleaner fish, which is a growing focus for both fish farmer and academic partners.”