Disease & heat resistance

From success to strategy: Genetics for health and sustainability in aquaculture

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Abstract

Selective breeding for disease resistance has been one of aquaculture's greatest success stories, with numerous examples of dramatic reductions in disease outbreaks and, in some cases, near elimination. Disease traits in fish often show moderate to high heritability, and genomic selection is now widely applied to maximise accuracy. Aquaculture species have also benefited from the relatively frequent occurrence of large-effect quantitative trait loci (QTL), providing breeders with powerful tools for rapid genetic gain at low cost across populations through marker-assisted and genomic selection. Rapid developments in genomic resources in recent years have further enhanced the effectiveness of these tools, for example by increasing marker density across genomes and enabling the use of markers in tight linkage disequilibrium with causal mutations that can be applied consistently across populations and year classes. Despite these advances, breeding for general robustness, defined here as the ability to survive and perform across variable environments and under exposure to diverse pathogens, remains challenging. Most disease resistance traits show low or no genetic correlation, meaning that when selection intensity is limited, breeding programmes must prioritise between long-term incremental gains and more immediate improvements for diseases with greater welfare, economic, or regulatory impact. In highly regulated aquaculture industries, incremental genetic progress may not keep pace with regulatory demands, often necessitating complementary interventions such as vaccines or management measures that can be deployed rapidly and, in some cases, mandated irrespective of genetic progress. Sea lice resistance in Atlantic salmon illustrates these complexities well. Although heritable, host-parasite dynamics, environmental variation, and scale effects can obscure genetic gains observed under controlled conditions, limiting the effectiveness of selection at the farm level. In this context, health and welfare impacts are often driven primarily by treatment frequency rather than parasite burden per se, implying that production traits such as growth rate can indirectly contribute to improved outcomes by shortening time to harvest. For many disease traits, increasingly stringent welfare regulations are also restricting the routine use of large-scale challenge tests, accelerating the need for alternative phenotyping strategies and greater reliance on genomic information. Looking ahead, breeding programmes must remain flexible, integrating genomic tools with innovative phenotyping approaches while anticipating regulatory and infrastructural change. Emerging technologies such as gene editing hold promise, but their added value may be greatest for complex or polygenic traits rather than those already amenable to rapid improvement through marker-assisted selection. For breeding companies, aligning breeding objectives with sustainability, welfare standards, and realistic intervention timelines will be critical to maintaining competitiveness in an increasingly complex production landscape.

Keywords: 2026

How to Cite:

Baranski, M., (2026) “From success to strategy: Genetics for health and sustainability in aquaculture”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286388. doi: https://doi.org/10.31274/wcgalp.23975

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