The southern red snapper, Lutjanus purpureus, is one of the primary fishery resources of the Amazon continental shelf. Due to the demand for specimens of less than 900 g in weight, increased fishing effort focusing on this size class has led to a drastic decrease in catches. The present study was based on the analysis of cellular structures in the female gonads (formation of oocytes and other reproductive tissues) to identify reproductive processes and evaluate the effectiveness of current fishery management practices. The presence of postovulatory follicles (POFs) peaked in April, which was interpreted as a period of intense spawning. In addition to POFs, hydrated oocytes peaked in July, indicating either reproductive continuity or a second peak, based on the presence of atretic oocytes and atresia. Given that the local snapper fishery preferentially targets very young individuals, an extension of the closed season from March to July would be recommendable to guarantee the reproductive potential of the spawning stock.