P. aztecus becomes reproductive after reaching a size of 140 mm (Renfro 1964). This species is known to have an extended spawning season that is likely to vary in different geographic areas of its range. Gonads mature in August and become opaque white, yellow or tan in color when fully ripe (Broad 1950; Brown and Patlan 1974). Brown shrimp spawn offshore at depths that generally exceed 18 m (Larson et al. 1989)Data from Burkenroad (1939) showed that sex ratios of P. aztecus change with water depth. In Louisiana waters, the sex ratio nearshore is balanced at approximately 1:1. However, in deeper waters ranging from 90 - 130 m in depth, the sex ratio changes to 1:2 in favor of females. Impregnated females in these waters occurred only beyond 18 m depth. This occurrence pattern is suggestive that spawning sites for P. aztecus are likely to be further offshore in deeper waters than occurs in other Penaeids such as P. dourarum (pink shrimp) and P. setiferus (white shrimp).