Characterisation of Fatty Acid Profiles in Tasmanian Atlantic Salmon Muscle, Oocytes and Eggs in Differing Fully Commercial Settings

Abstract

Tasmanian Atlantic salmon broodstock may be conditioned in flow-through (FT) systems where water quality fluctuates and temperatures approach their upper limit of thermal tolerance, or in recirculating aquaculture systems (RAS) where conditions are comparatively cool and stable. The impact of broad conditioning approach on the molecular cargo of salmon eggs has never been explored in dynamic commercial settings. Therefore, this study aimed to characterise the reproductive features of broodstock conditioned using different commercial approaches and determine whether the fatty acid (FA) profiles of muscle, oocytes and eggs varied between groups during vitellogenesis and at stripping. The collective conditioning approach had a marked impact on the somatic and reproductive dynamics of female salmon broodstock, and the eggs produced by each group of fish were fundamentally different in terms of their FA composition. Of particular note is the increased maternal investment of saturated FAs (mg.g⁻¹) and monounsaturated FAs (percent and mg.g⁻¹) by FT-based eggs, and the higher n3 polyunsaturated FA (percent and mg.g⁻¹), docosahexaenoic acid (DHA, percent and mg.g⁻¹), arachidonic acid (ARA, percent), eicosapentaenoic acid (EPA, percent), n3:n6 ratio and ARA:EPA ratio of RAS-based eggs. These metrics combined with the apparently higher prevalence of neural development and survival of RAS embryos suggest that RAS eggs were of higher quality. On the other hand, there is evidence to suggest that FT broodstock attempt to prepare their offspring for a (presumably) challenging early life environment by producing larger eggs that are proportionally rich in short-chain FAs and contain a higher total quantity of FAs per egg.