A team of international aquaculture researchers has made a significant breakthrough with the identification of two new genetic markers that indicate greater resistance to a bacterial infection in Atlantic salmon.

In a project backed by the Sustainable Aquaculture Innovation Centre (SAIC) and led by AquaGen Scotland, with partners from the University of Stirling’s Institute of Aquaculture, DawnFresh Farming, and Cooke Aquaculture Scotland, the consortium explored the genetics that determines whether fish are resistant to Flavobacterium psychrophilum, a bacteria which can lead to health issues in salmon fry.

The scientific milestone is expected to pave the way for selective breeding programs, which could boost the health and welfare of farmed Scottish salmon by breeding new fish from parents that possess the genetic resistance markers and are, therefore, expected to display increased resistance to the bacteria.

Flavobacteriosis can be a particular threat to smaller, juvenile fish and is a widespread challenge for the aquaculture sector, with infections also reported in Chile, Norway and Canada. However, current prevention and treatment programs are limited. Vaccination by injection cannot be used due to the size of the fish and, as the sector continues to move away from antibiotic treatments, a genetic breakthrough could hold the key.

Andrew Reeve, managing director at AquaGen, said that “continual improvements in fish health and welfare are priorities for the aquaculture industry, to which robust stock suited to the farmed environment makes an important contribution. Genetic markers for disease resistance, such as those discovered through this SAIC-funded project, are valuable tools that can and will be immediately employed in breeding work.” 

To identify the two genetic markers, more than 4,000 fish from AquaGen were tested for more than 70,000 genetic markers using a specially designed lab-based model, which mimics the natural infection route. The next stage of the research program is to conduct field trials at one of Cooke Aquaculture’s sites using salmon eggs specifically selected by AquaGen. It is hoped that in the event of a natural outbreak of the bacterial disease being detected, these fish can be tested to validate the effect of the genetic markers.

Rowena Hoare, research fellow at the Institute of Aquaculture, said that “Flavobacteriosis is known to be problematic for salmonid culture in freshwater globally for decades. This project has shown how fruitful it can be to combine the expertise of academic and industry researchers to address a complex and economically important disease.”