Climate change is no longer a distant challenge for aquaculture; it is an operational reality. Around the world, farms are already feeling the impact of more frequent and severe environmental stress events. Fluctuations in temperature, dissolved oxygen, salinity, and other key water parameters are affecting performance, stability, and predictability.
At Xelect, and particularly in my role as a breeding programme manager, one message is increasingly clear: environmental resilience is a key component for the long-term viability of the aquaculture industry.
Understanding G×E: A Critical Factor in Modern Breeding Decisions
At the heart of this challenge is genotype-by-environment interaction (G×E), a phenomenon that occurs when genotypes respond differently to a change in their environment. A genotype that performs exceptionally well under one set of conditions may underperform, or even fail, in another. This often leads to changes in the rankings of genotypes, which reduces prediction accuracy and lowers response to selection. As climate change amplifies environmental variability and unpredictability, incorporating resilience into our breeding objectives can mitigate the effects of a changing environment.
Historically, aquaculture breeding programmes have been designed around practical constraints including limited testing sites, restricted capacity to measure environmental parameters, and the need to manage biosecurity and logistics. As a result, selection decisions were typically made using performance data from a narrow set of conditions. While this approach delivered substantial early gains in growth and other economically important traits, it also meant that breeding programmes increasingly favoured genotypes highly adapted to specific conditions and potentially more sensitive to environmental variation, leading to greater re-ranking when conditions vary. With climate change increasing environmental variability, the correlation between the controlled environments where selective breeding decisions are made and the real-world farming environments where performance is desired is decaying more and more rapidly.
From a breeding programme management standpoint, G×E is not a complication to avoid or an inconvenient source of noise, but rather essential information to improve our selection decisions. Recent research has demonstrated that G×E can be effectively characterised and leveraged to enhance breeding outcomes. By understanding how genetic performance shifts across fluctuating temperature profiles, oxygen levels, salinity gradients, or pathogen load, we can design breeding strategies that better reflect real-world environmental complexity. This enables more predictable and stable responses to selection, even as production environments become less predictable. In some cases, this means identifying robust genotypes that perform consistently across different production environments, while in others, it means developing targeted, environment-specific lines optimised for particular farming conditions.
Environmental resilience in aquaculture is far more than survival under stress. It encompasses growth, stress tolerance, feed efficiency, health, behaviour, reproductive performance, and product quality across a wide range of environmental scenarios. Selection for resilience requires deliberate and precise exposure of closely related individuals to relevant and carefully controlled environmental variability. When combined with accurate and repeatable phenotyping and modern genotyping technologies, we can better understand how populations respond to stress or change, and select directly for it. Without this, breeding programmes risk producing animals that excel only in a set of idealised, perfect conditions that are predictable and stable — conditions that are becoming far less secure in a changing climate.
Building Resilient Aquaculture for an Unpredictable Future
As breeding programme managers, we have a responsibility to translate G×E insights into practical, forward-looking solutions for producers around the world. This means designing environmental testing strategies, applying genetic models that explicitly account for G×E, and supporting clients in collecting accurate phenotype, genotype, and environmental data to strengthen selection decisions and mitigate future climate risks. Importantly, it also means helping the industry shift its mindset: environmental resilience is a performance trait, and it can be improved through careful and informed selection.
Modern aquaculture will be built on breeding programmes that respect the complexity of real farming environments. G×E is not just a theoretical concept; it is a practical framework for aligning genetics with a rapidly changing world. By incorporating it, the industry can move from reacting to individual climate-related stressors to proactively breeding populations that thrive in spite of them.
Around the world, producers are already demonstrating remarkable adaptability, innovation, and commitment to long-term sustainability. By integrating environmental resilience into breeding decisions today, we are not only safeguarding performance for tomorrow, but we are also securing the foundation for an aquaculture sector that can thrive in an unpredictable climate. At Xelect, we see firsthand how quickly progress can be made when genetics, accurate data, and real-world farming expertise come together with a shared purpose.
With the right tools, the latest science, and the right mindset, producers can turn environmental uncertainty into a strategic advantage and profit. The challenge ahead is significant, but so is the opportunity. By harnessing G×E to build environmental resilience, the global aquaculture community has every reason to face the future with confidence.
About the Author
Duncan Henderson is a Breeding Programme Manager at Xelect, specialising in the design and implementation of advanced selective breeding strategies. His work focuses on integrating genotype-by-environment insights to support producers adapting to a changing climate.
