Evaluating a dual-energy X-ray absorptiometry protocol to determine the body composition of Atlantic Salmon (Salmo salar)

Knowledge of fish proximate composition is vital for farmers and researchers to make proactive management decisions and informed research interpretations. Currently, this is a cumbersome process requiring destructive sampling and specialised laboratory methods. This study strengthens the decision-making process for farmers and researchers by evaluating a rapid method for understanding fish proximate composition. We hypothesise that dual-energy X-ray absorptiometry (DXA) technology, designed and intended for human and livestock subjects, may also prove applicable for aquatic life. If proven, it enables a rapid, non-invasive and harmless method for analysing fish proximate composition and prediction of overall condition. In this study, we compare a DXA protocol with gold-standard “comparative slaughter techniques” (CST) of laboratory analysis for the examination of whole-body composition in Atlantic salmon ( Salmo salar ). The DXA results demonstrated a high degree of correlation (>0.90) with CST analyses for total mass, fat mass and lean mass analysis. However, there was less agreement between the methods for bone mineral content analysis. Furthermore, regression equations generated from the dataset can predict CST equivalents for fat, lean and total mass with high precision. We conclude that DXA is a feasible substitute over traditional laboratory analysis methods and warrants further study. • DXA is a rapid and accurate method for composition analysis in live Atlantic salmon. • Highly correlated scans can be completed in approximately 5 min. • DXA can improve the efficiency and cost of proximate analysis methods. • Regression equations generated from the dataset can predict with high precision. • Improved welfare of fish with non-destructive proximate analysis.