Reproductive biology of the starry grouper, Epinephelus labriformis (Perciformes: Serranidae): Gonadal development, sex change and sexual pattern.

The reproductive biology of the starry grouper, Epinephelus labriformis, in Mazatlan Bay, Mexico, was studied through histological analysis of the gonads. A total of 527 fish were examined through weekly sampling from March 2017 to March 2018. In this species, the gonads are bilobed and connected to a common gonoduct. E. labriformis exhibits monandric protogynous hermaphroditism, with a female-to-male proportion of 1.5 females:1 male in fully mature animals. In females, six ovarian phases were identified, and the oogenic cycle was analysed in 314 females, classified as asynchronous. The gonadosomatic index increased from 0.13 in the immature phase to 3.35 at maturity, declining to 1.16 post-spawning. Transforming testes (n = 95) revealed four stages of sex change, during which ovarian tissue is progressively replaced by testicular tissue. Males and transforming individuals appeared in larger size classes, with no females recorded beyond 27.5 cm total length (Lt). Females reach sexual maturity at 17.2 cm Lt. In comparison, males mature at 19.42 cm Lt. Sex change occurs in individuals with total lengths ranging from 20 cm to 33.5 cm Lt, with an average size for sex change of 24.7 cm. Our findings define the reproductive strategy of E. labriformis. They also provide actionable guidelines for fisheries management in Mexico. In the absence of specific regulations in Mexico, we recommended establishing a minimum catch size between 24 and 27 cm Lt and seasonal protection during the reproductive period to preserve spawning potential and maintain a balanced sex ratio in the population.