Abstract
Atlantic salmon is a commercially important salmonid species facing ongoing challenges in broodstock and gamete management, where oocyte quality represents an important factor influencing reproductive success. In this study, we combined physicochemical analysis of oocytes and ovarian fluid (OF) with proteomic profiling of selected embryonic stages i.e., eyed egg and hatched larvae to identify candidate indicators associated with oocyte quality in commercial aquaculture. Significant associations were observed between OF properties and fertilisation outcome: aspartate aminotransferase (AST) enzyme activity in OF and pH exhibited the strongest correlations with fertilisation and eyed egg success. OF osmolality and relative weight gain during water hardening (RWH) in oocytes were also associated with variation in oocyte performance. Proteomic profiling revealed proteins associated with proteostasis, translation, calcium regulation, lipid metabolism, and immune and inflammatory responses. Notably, 135 proteins were significantly correlated with fertilisation outcome, of which 80 were identified in OF, suggesting that the surrounding biochemical environment may be associated with oocyte viability.