The plasma metabolome of Atlantic salmon as studied by H NMR spectroscopy using standard operating procedures: effect of aquaculture location and growth stage

Introduction: Metabolomics applications to the aquaculture research are increasing steadily. The use of standardized proton nuclear magnetic resonance (H NMR) spectroscopy can provide the aquaculture industry with an unbiased, reproducible, and high-throughput screening tool, which can help to diagnose nutritional and disease-related metabolic disorders in farmed fish. Objective: Standard operating procedures developed for analysing (human) plasma by H NMR were applied to fingerprint the metabolome in plasma samples collected from Atlantic salmon. The aim was to explore the metabolome of salmon plasma in relation to growth stage and sampling site. Methods: A total of 72 salmon were collected from three aquaculture sites in Norway (Lat. 65, 67, and 70 °N) and over two sampling events (December 2017 and November 2018). Plasma drawn from each salmon was measured by H NMR and metabolites were quantified using the SigMa software. The NMR data was analysed by principal component analysis (PCA) and ANOVA-simultaneous component analysis (ASCA). Results: Important metabolic differences were evidenced, with adult salmon having a much higher content of very low-density lipoproteins and cholesterol in their plasma, while smolts displayed significantly higher levels of propylene glycol. Overall, 24% of the metabolite variation was due to the growth stage, whereas 12% of the metabolite variation was related to the aquaculture site and practice (p < 0.001). Conclusion: This study provides a baseline investigation of the plasma metabolome of the Atlantic salmon and demonstrates how H NMR metabolomics can be used in future investigations for comparing aquaculture practices and their influence on the fish metabolome.