ABSTRACTResults of 32 collection cruises forPenaeus setiferusadults over a 3‐year period in the northwestern Gulf of Mexico are reviewed to document incidence of capture of mature females, mating incidence by time of day of capture, and larval production from natural and artificial inseminations. Mean number of eggs per spawn by year for natural inseminations ranged from 197,000–309,000 (n=160) and for artificial inseminations, 136,000–300,000 (n=174) for females averaging 38–45 g. Mean percent hatch for natural inseminations ranged from 35.3–72.8, and for artificial inseminations, 14.7–77.8. The percentage of females captured from 0900–1600 hours which were mated ranged from 0–13%, while 9–42% of those captured from 1600–2200 hours were mated. The strongest diurnal increase in mating activity occurred from 1600–1800 hours. Three mated conditions, characterized by 1) a complete compound spermatophore; 2) the “wings” or anterior portion of the spermatophore only; and 3) a sperm mass only, represented 28.4%, 38.3%, and 33.3%, respectively, at time of capture. A significant relationship was found between spermatophore stage and hour of capture (P<0.149), suggesting there may be a sequential breakdown of the sperma