Effects of Differential Commercial Husbandry Conditions on the Tasmanian Atlantic Salmon Egg Transcriptome

Maternally inherited transcripts are crucial for the developmental competence of salmon embryos. Due to the wide variety of broodstock conditioning approaches used in commercial aquaculture, there is a need to understand how dynamic commercial environments impact the egg transcriptome and subsequent quality. In this study, the transcriptomic profile of eggs was dependent on the broodstock conditioning approach, with 156 isoforms significantly down-regulated and 105 significantly up-regulated in the flow-through (FT) relative to the recirculating aquaculture system (RAS)-based group. In FT-based eggs, a down-regulation of genes related to survival (CCCTC-binding factor), growth (DEAH (Asp-Glu-Ala-His) box polypeptide 33), left-right pattern development (Protein canopy-1), and yolk hydrolysis (Cathepsin B) was observed, whereas up-regulation was observed for genes related to bone and tissue development (Metalloproteinase inhibitor 2) and energy production (Cytochrome c oxidase II, mitochondrial). Subsequent embryo quality (neural streak development, embryo survival, and developmental progression) was apparently lower in the FT-based group. As such, there is evidence to suggest that routine husbandry approaches (and associated differences in water quality) have a significant impact on egg quality, and this is underpinned, at least in part, by changes in the maternally inherited transcriptome.