Red Snapper Reproductive Biology in the Southern Gulf of Mexico

Abstract

Sex ratio, size at maturity, reproductive periodicity, ovarian development pattern, and spawning ground data for red snapper Lutjanus campechanus from the southern Gulf of Mexico were analyzed to understand this species' reproductive biology throughout its geographical distribution. Red snapper were sampled in 1999 and 2000 from commercial fishery catches taken on Campeche Bank at depths ranging from 43 to 130 m. Overall sex ratio (male: female) and sex ratios by size-class did not differ significantly from a 1:1 ratio. First maturity was at a slightly smaller size in males (24.2 cm total length [TL]) than in females (28.3 cm TL), and maximum length percentages at first maturity were 28% for males and 34% for females. The length at which maturity was attained in 50% of females (L50) was 31.4 cm TL. The Campeche Bank red snapper stock had a protracted spawning period from February to November, with a spawning peak occurring in early fall. Vitellogenic oocytes were continually recruited from previtellogenic oocytes during the entire spawning season, with no gap between each oocyte development stage. This means that red snapper ovaries are asynchronous and that the species can be considered a heterochronal (batch) spawner with indeterminate annual fecundity. Females in spawning condition were collected from both the northeastern and northwestern areas of Campeche Bank, near submerged or emergent coral reef structures, and at depths between 48 and 117 m. These results generally agreed with those for red snapper stocks in others regions of the Gulf of Mexico and the Atlantic Ocean off the southeastern United States. However, reproductive periodicity in the Campeche Bank red snapper stock apparently displayed more of an insular pattern of extended spawning in comparison with the typical continental pattern of restricted spawning reported for other regions. The latitudinal differences observed in red snapper spawning seasons could also reflect a latitudinal gradient in the intensity of seasonal environmental constraints.