Metabolomic responses of Atlantic salmon (Salmo salar) cultured during the pre-smolt, smolt and post-smolt stages

Abstract

Atlantic salmon (Salmo salar) is an anadromous salmonid that commonly undergoes a transfer from land-based freshwater hatcheries to ocean-based sea pens for cultivation. For investigating the metabolomic response properties in the cultured Atlantic salmon (∼ 400 g, n = 8 in each group) during the pre-smolt, smolt and post-smolt stages, we performed LC-MS/MS metabolomics to assess the metabolomic responses on the brain and skin of Atlantic salmon. A total of 153 and 115 differentially expressed metabolites (DEMs) exhibited significant variations in the brain and skin, respectively. These metabolites were mainly involved in three metabolic categories of amino acids, organic acids and fatty acids. In the brain, metabolites associated with cortisol synthesis and secretion and biosynthesis of cofactors were highly induced in the smolt stage compared to the pre-smolt stage, while in the post-smolt stage, levels of lipid and amino acid notably reduced. Moreover, 3-(3-hydroxyphenyl) propanoic acid, mannose 6-phosphate, cortisol, thymine, and guanine, as candidate smolting metabolites in the brain, displayed life stage-dependent alterations. In the skin, 3-methoxytyramine, L-sepiapterin, and nucleotide metabolism differed significantly during smoltification. Overall, these results reveal diverse life-stage-associated metabolomic responses in Atlantic salmon and provide important information for the aquaculture of Atlantic salmon.