Abstract : The study examined the histology and biochemical composition of the gonads of male and female Mytilus galloprovincialis molluscs that were harvested in the winter of 2023 from three different locations in the Gulf of Annaba: Seraïdi, Chapuis, and Sidi Salem. The results obtained indicate that during the winter, the mussels at all three sites had high protein levels, with the Seraïdi site having the highest value. However, there was no discernible variation in their carbohydrate levels. There is no discernible change in the histology of the gonads between the sex or all three sites. Each of the foundations has to do with the kind and extent of contamination these locations are exposed to. Indeed, because of its proximity to the port of Annaba and a factory that specializes in the production of phytosanitary goods, the Sidi Salem site is contaminated by both industrial and port sources. However, contamination from agricultural and urban sources affects the Chapuis site.