Modeling reproductive dynamics and environmental influences on the European hake (Merluccius merluccius L.) in Moroccan Mediterranean Sea

Understanding the reproductive biology of commercially important species is essential for sustainable fisheries management. The European hake, Merluccius merluccius , is a key demersal species in the Mediterranean, yet knowledge of its reproductive patterns in the Moroccan Mediterranean Sea remains limited. Here, we addressed this gap by examining the reproductive cycle, sex ratio, and environmental influences on gonadal development. From 2015 to 2019, morphometric parameters were measured for 4780 individuals sampled monthly from commercial bottom trawlers. The overall sex ratio (M:F) was biased toward females, with notable variation across size classes and months: females dominated larger size classes, while males were more prevalent in smaller ones. Spawning individuals were recorded year-round, indicating asynchronous reproduction , with a pronounced peak in June, as evidenced by trends in the gonadosomatic index (GSI). HIS results suggest a mixed reproductive strategy, in which both income and capital breeding occur simultaneously, leading to multiple spawning peaks throughout the year. Generalized Additive Models (GAMs) revealed that variations in GSI were strongly influenced by both environmental (Temperature and salinity) and biological (condition factor and hepatosomatic index) factors. These findings provide the first comprehensive assessment of M. merluccius reproductive biology in the Moroccan Mediterranean, offering valuable information to support science-based management and conservation of this commercially important species.