Reproductive performance of the mussel Mytilus galloprovincialis (Lamarck, 1819) cultivated in two areas of southern Portugal

Abstract The optimisation of offshore mussel production is crucial to meet market demand. Understanding of the reproductive performance of Mytilus galloprovincialis enables the maximisation of larval recruitment by timely adjusting the deployment of collector ropes. In this study, the reproductive cycle of M. galloprovincialis produced at two offshore sites along the Algarve coast (Olhão and Lagos) was evaluated using histological analysis of gonads, biochemical composition, and condition index. Surface sea water temperature (SST) and chlorophyll a (Chl a ) were recorded to assess the effect of these factors on the reproductive cycle. Although reproductive patterns differ between the two years of the study, both sites exhibited a higher reproductive effort in late spring 2014. No specific spawning period was observed, with mussels under successively and continuously gonadal recovery and spawning throughout most of the study. No clear correlation with SST and Chl a was found in the current study. At both sites, glycogen content and gonadal index revealed opposite patterns, showing a rapid gonadal recovery after spawning. The current study provides valuable insights for improving farm profitability by supporting more effective production management strategies.