Biochemical composition of the ovarian fluid and its effects on the fertilization capacity of turbot Scophthalmus maximus during the spawning season

This study investigated the biochemical composition of ovarian fluid and its effect on the fertilization capacity of turbot Scophthalmus maximus during the spawning season. The fertilization rate and pH of ovarian fluid varied throughout the spawning season, with the highest values recorded at the mid‐season. Positive correlations were found between the fertilization rate and the ovarian fluid pH. The composition of major inorganic ions (Na+, K+, Ca2+ and Cl−) showed no significant changes during the spawning season. Alkaline phosphatase (AKP) activity was significantly higher during mid‐season than other seasons. The lowest levels of protein, acid phosphatase (ACP) and aspartate aminotransferase (AAT) were in the ovarian fluid released at the mid‐season. Moreover, significant relationships were observed between the fertilization rate and the levels of protein, ACP, AKP and AAT. These observations suggest that the biochemical profile of ovarian fluid affects the insemination microenvironment as well as the fertilization capacity of S. maximus eggs. Determination of such profiles may prove to be a useful strategy to improve S. maximus breeding techniques.