Despite its commercial importance and high vulnerability to fishing impact, little is known about the reproductive biology of the Tiger Grouper Mycteroperca tigris, an aggregative spawner. We studied the key reproductive parameters of this species in the southern Gulf of Mexico, where the grouper fishery is generally in decline. The smallest mature female measured 31.4 cm FL, and length at which maturity was attained in 50% of females (L50) was 34.2 cm FL. Tiger Grouper are protogynous hermaphrodites, and the estimated length at which 50% of females had changed sex was 51.9 cm FL. Spawning season lasted from February to June, with a spawning peak observed in April. Most of the actively spawning females were collected 7–14 d after the full moon in April and May. Females exhibited continuous, asynchronous oocyte development and batch release of mature oocytes. During April–June, estimated spawning interval varied monthly from 1.8 to 4.3 d (mean = 2 d). Due to the species’ indeterminate fecundity, we estimated batch fecundity, which ranged from 84,119 to 1,032,578 oocytes (mean ± SE = 417,102 ± 34,826 oocytes). Conservation status of the Tiger Grouper in its distribution area is currently unclear. Based on the observed maximum sizes for both sexes and the size of sexual transition, the southern Gulf of Mexico Tiger Grouper population may be healthier than some Caribbean Sea populations. Current and potential measures for regulating this fishery resource in the southern Gulf of Mexico are discussed.

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Snappers exhibit reproductive trait plasticity in response to habitat distribution. Lutjanus griseus is among the most economically important snappers in the western Central Atlantic but has received limited study in the region. Data on the reproductive biology of the L. griseus population were collected on the continental shelf of the Yucatan Peninsula, Mexico. Over a nineteen-month period, 1236 specimens were captured monthly in three Yucatan artisanal fishing fleet operational areas. Data were grouped by month to generate an annual analysis. Individual sex and maturation status were identified by gonad histology. Median size did not differ between females (33.2 cm fork length [FL]) and males (33.3 cm FL), and the sex ratio was balanced (F:M=0.98:1.00). Size at maturity was 24.2 cm FL for females (38% of maximum size reported for the species) and 22.8 cm FL for males (36% of maximum size), and the spawning season ran from May to September. The results confirm that this population exhibits the typical reproductive pattern of snappers distributed on continental shelves or in shallow water areas and provide critical data for stock assessment and implementation of management measures for L. griseus stock in the southern Gulf of Mexico.