Complex Gill Disease (CGD) remains a major challenge in salmon aquaculture. New research from Benchmark Genetics shows that genetic resistance to CGD is heritable and can be improved using genomic selection – opening the door to healthier robust salmon, improved welfare, and more sustainable production.
Gill health is essential for Atlantic salmon. The gills allow fish to breathe, regulate salt balance, and protect against pathogens. When gill function is compromised, fish health, welfare, and farm performance can all be affected. One of the most challenging gill-related conditions in salmon farming today is Complex Gill Disease (CGD).
Recent scientific research from Benchmark Genetics has shown that genetics plays an important role in how well salmon cope with CGD. These findings highlight new opportunities to improve fish health and resilience through selective breeding.
“Genetics gives us a powerful way to improve the natural resilience of salmon,” says Dr. Andrew Preston, Lead for Trait Development and Land- Based at Benchmark Genetics. “By selecting fish with stronger resistance to CGD, we can support healthier stocks and more sustainable aquaculture for the future.”
What Is Complex Gill Disease?
Complex Gill Disease 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.
Can Salmon Be Bred to Better Resist CGD?
To answer this question, 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.
Key Findings Explained Simply
Genetics Matters
The study found that resistance to CGD has a moderate genetic component. This means that a noticeable part of how well a fish handles CGD is passed from parents to offspring. In practical terms, this makes resistance something that can be improved through selective breeding.
Many Genes Work Together
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.
Genomics Improves Selection
By using genomic information, researchers were able to predict which fish were more resistant to CGD with high accuracy. This shows that genomic tools can help breeding programs make better selection decisions earlier and more reliably.
Efficient Health Scoring
The research also showed that gill damage was consistent across different gill areas. This means that health assessments can be simplified, saving time and effort while still providing reliable information.
Why This Matters for Salmon Farming
Breeding salmon with improved resistance to CGD offers several important benefits:
- Better fish welfare through stronger natural resilience
- Lower disease impact, reducing stress and losses
- Less reliance on treatments, supporting more sustainable production
- Improved long-term performance in challenging environments
Genetic improvement does not replace good management, but it strengthens the fish’s ability to cope with real-world farming conditions.
Building a More Resilient Future Through Genetics
This research confirms that genetics is a powerful tool in addressing Complex Gill Disease. By selecting fish with naturally stronger resistance, breeding programs can help deliver healthier salmon generations over time.
At Benchmark Genetics, insights like these support our commitment to science-based breeding, improved fish health, and sustainable aquaculture. Through continued innovation and responsible genetic improvement, we can help farmers meet today’s challenges and prepare for tomorrow’s.
Read the publication here: https://www.frontiersin.org/journals/aquaculture/articles/10.3389/faquc.2025.1541010/abstract
If you have questions about the publication Dr. Andrew Preston by andrew.preston@bmkgenetics.com.
