Gill Health

CGD is a complex, multifactorial condition. It is not caused by a single factor, instead, it develops through a combination of environmental stress, biological challenges, and fish response. Affected salmon may experience damaged gill tissue, reduced ability to breathe efficiently, slower growth, and increased vulnerability to further health problems.

Because CGD is complex and difficult to control through management alone, the aquaculture industry is increasingly looking toward long-term, preventive solutions – including genetics.

Rather than one single “CGD resistance gene,” resistance is influenced by many genes, each contributing a small effect. This type of trait is common in nature and is well suited to modern genomic breeding approaches.

Benchmark Genetics steps into the frontline to support salmon farmers facing gill disease challenges by incorporating genomic selection for gill health into its breeding strategy. Our R&D team has led a focused research initiative in collaboration with customers and academic partners such as the University of Stirling’s Institute of Aquaculture.

Our researchers studied a large population of Atlantic salmon from a breeding program. The fish were exposed to CGD under controlled conditions that reflected real farming environments. After exposure, the severity of gill damage was carefully measured, and the genetic profiles of the fish were analysed.

The results were clear: some salmon are naturally more resistant to CGD than others, and this difference is partly inherited.

Publications

Preston AC, MacKenzie S, Fannemel B, Clokie B, Matthew C, Bassett D, Moghadam H, Kristjánsson ÓH, Thorland I, Vela-Avitua S, Lozano C, Houston RD and Nirea K (2026) The genetic basis of resistance to complex gill disease in Atlantic salmon (Salmo salar). Front. Aquac. 4:1541010. doi: 10.3389/faquc.2025.1541010