Sustainability & efficiency

Documentation of Genetic Gain for Growth in Atlantic Salmon Breeding Program

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Abstract

Quantifying realized genetic gain is fundamental to evaluating the long-term impact of selective breeding in aquaculture. In Atlantic salmon (Salmo salar), AquaGen's breeding program has achieved continuous improvement in growth through 13 generations of selection. While genomic estimated breeding values (GEBVs) provide model-based predictions of progress, empirical validation under controlled and comparable environmental conditions remains essential to confirm realized gain in commercial environments.To empirically document genetic gain for growth, a documentation group (halflings) was established within the AS24 nucleus from generation 13. Halflings were produced by fertilizing eggs from current nucleus females (AS21) with cryopreserved milt from males one generation older (AS17 to AS19). These offspring are genetically intermediate between two consecutive generations, providing a practical and unbiased method for quantifying intergenerational improvement without relying solely on statistical models. Phenotypic differences between halflings and current nucleus families (NUC) were evaluated under identical rearing conditions to estimate realized genetic gain.Testing was conducted at AquaGen's freshwater and seawater test facilities (Hemne and Tingvoll). Body weights were recorded at multiple production stages: freshwater (vaccine weight), early seawater (three-month sea), and harvest (slaughter and live-end weights). Genetic gain was estimated as twice the mean difference between the current nucleus and halflings, based on the assumption that halflings are at the genetic midpoint between generations.Across test sites and production phases, consistent and substantial phenotypic differences were observed, confirming significant genetic progress in growth. Estimated relative genetic gains per generation were 10 to 13% for freshwater vaccine weight, 15.1% for three-month seawater weight at Tingvoll, 11 to 13% for slaughter and gutted weights at Tingvoll, and approximately 19% for seawater harvest weight at Hemne.In addition to documenting phenotypic improvement, the inclusion of reference males across generations strengthens the genomic evaluation framework. By linking performance data with genotypes across generations, the accuracy and continuity of GEBV estimation are improved, resulting in more precise genetic trend analyses. This closer integration between phenotype, generation, and EBV enhances the connection between measured performance and breeding values, allowing fish farmers to relate realized growth performance more directly to EBVs than has traditionally been possible in aquaculture.These findings demonstrate a realized genetic gain of 10 to 20% per generation for growth in AquaGen's Atlantic salmon breeding program. The strong agreement between empirical and predicted improvements supports the robustness and consistency of the selection process. The halfling-based documentation approach provides a transparent and scientifically sound method for verifying genetic progress, and its continued use is recommended for maintaining accurate monitoring of realized genetic improvement across future generations.

Keywords: 2026

How to Cite:

Bangera, R., Kjøglum, S., Korsvoll, S. & à˜degà¥rd, J., (2026) “Documentation of Genetic Gain for Growth in Atlantic Salmon Breeding Program”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2287231. doi: https://doi.org/10.31274/wcgalp.24243

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