A new study published in Aquaculture has documented a 76 percent genetic improvement in harvest weight in gilthead seabream over more than 20 years of selective breeding, making it one of the most comprehensive long-term assessments of genetic progress in a marine aquaculture species.
Conducted by Benchmark Genetics in collaboration with Avramar, the research draws on production and pedigree data from almost 124,000 gilthead seabream (Sparus aurata) across 1843 families produced between 2002 and 2023. The study reflects more than two decades of collaboration on one of the Mediterranean’s longest-running commercial seabream breeding programmes.
Over the course of the programme, researchers recorded a cumulative 76 percent genetic improvement in harvest weight, equivalent to around 15 percent genetic gain per generation and an average annual gain of 3.6 percent. The programme also maintained low levels of inbreeding while preserving genetic diversity.
In addition to documenting long-term genetic progress, the study highlights the wider benefits of selective breeding for modern aquaculture. Faster growth rates have the potential to shorten production cycles, improve resource utilisation, reduce biological risk, and strengthen the long-term sustainability and competitiveness of aquaculture production. Although the research focused on harvest weight, the breeding programme has also used multi-trait selection to improve commercially important characteristics including robustness, survival and product quality.
“Long-term datasets of this quality are exceptionally rare in aquaculture,” said Ingunn Thorland, Senior Geneticist at Benchmark Genetics and lead author of the study. “This study demonstrates that well-designed breeding programmes can deliver sustained genetic improvement over decades while maintaining the genetic diversity needed for future progress. It provides strong scientific evidence of the long-term value of selective breeding for aquaculture.”
Nikos Katribouzas, Group Genetics and R&D Manager at Avramar, said the publication reflects more than 20 years of continuous development of the company’s breeding programme. “The documented genetic gains confirm the value of long-term investment in selective breeding and provide a strong foundation for the continued development of the programme,” he said.
The researchers say the study also provides one of the clearest examples of realised genetic gain achieved under commercial farming conditions, demonstrating that sustained genetic improvement can be achieved while responsibly managing genetic diversity.
With global demand for sustainable seafood continuing to increase, the findings reinforce the role of selective breeding as an effective and sustainable approach to improving biological performance, production efficiency and the long-term competitiveness of aquaculture. The research also provides a foundation for integrating genomic technologies into commercial breeding programmes to support further improvements in productivity, health and resilience.
The study, Sustained genetic gain for harvest weight in gilthead sea bream (Sparus aurata) over more than twenty years of selective breeding, by Thorland et al. (2026), is published in Aquaculture – https://www.sciencedirect.com/science/article/abs/pii/S0044848626006745
