Search

The three most important grouper fishery species in southern Gulf of Mexico, Epinephelus morio, Mycteroperca bonaci and Mycteroperca microlepis, do not have life history parameters data reported such as growth, age and natural mortality essential to management. Individuals from the three species were captured in the Campeche Bank (CB) at different times from 1988 to 2001. Sagittae were thin‐sectioned to count annuli: n = 1081 for E. morio, n = 920 for M. bonaci and n = 251 for M. microlepis. Otoliths from the three species exhibited successive opaque and translucent bands deposited with an annual frequency, occurring between January and April for E. morio and M. bonaci, and between January and March for M. microlepis. Estimated age in the three grouper species ranged from 0+ to 20 years. The most frequent ages were 7–10 years for E. morio and 8–12 years for M. bonaci and M. microlepis. The von Bertallanfy Growth Function model parameters (L∞, K and t0) were consistent with reported growth patterns for Epinephelidae family species, as established by growth performance Ф' (near 3). The CB groupers appear to reach maximum ages over 13 years with K values between 0.09 and 0.12 year−1, indicating all three studied species displayed relatively slow growth rate and medium longevity. Lifespan values ranged from 13 to 33 years for E. morio, from 18 to 30 years for M. bonaci and from 17 to 33 years for M. microlepis. A50 was 6.1 years for E. morio and 5.5 years for both M. bonaci and M. microlepis. Age at which all females were mature was 8 years for M. bonaci and 10 years for E. morio and M. microlepis. P50 was 9.3 years for E. morio, 13.6 years for M. bonaci and 11.6 years for M. microlepis. Age at which 100% of individuals were male was 13 years for E. morio, 19 years for M. bonaci and 15 years for M. microlepis. Values of M at age exhibited an exponential decrease with age for all three species, but overall values were 0.13 year−1 for E. morio, 0.14 year−1 for M. bonaci and 0.17 year−1 for M. microlepis. For the three species size at age varied by geographical distribution area, but particularly for E. morio the discrepancy in average size between published studies may be the consequence of the fishing effort exerted on the stock and/or the lack of regulation for the fishery prior to 2001; after this stock biomass fell below the reference limit point and was declared overexploited. Resource managers could use the information provided in this study as a reference, representing pre‐overexploitation values, to evaluate the current status of these populations and ensure sustainable management actions for the CB grouper fisheries. [ABSTRACT FROM AUTHOR]

Reproductive strategy in snapper seems directly related to whether a population or a species occurs over a continental or insular habitat. Since studies on Lane Snapper Lutjanus synagris reproduction have been mostly focused on populations associated with islands, the purpose of this work was to assess the reproductive strategy of a continental shelf population. Specimens (n = 1,165) sampled in the southern Gulf of Mexico along the northern coast of the Yucatan Peninsula between February 2008 and April 2010 were analyzed through histological examination of gonads. A male‐biased overall sex ratio was observed, with females being preponderant in larger size‐classes. As expected, the Yucatan population displayed the typical continental pattern of sexual maturity and reproductive seasonality. Percentage of maximum size at first maturity was less than 41% for both females and males, and the species reproduced in shallow waters (7–26‐m depth) all along the Yucatan coast, mainly between March and July, with spawning peaks observed in May and July. Lane Snapper exhibit asynchronous oocyte recruitment and batch spawning. Results of this study were compared with reproductive data available from both island and continental Lane Snapper populations. It was observed that Lane Snapper populations do not always conform to the pattern of reproductive seasonality and/or size at sexual maturity with regard to habitat type. This study contributes new information concerning the Lane Snapper’s reproductive strategy with regard to habitat type and depth and offers valuable information for the establishment of management strategies designed for Lane Snapper from the southern Gulf of Mexico. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Sex ratio, size at maturity, reproductive periodicity, ovarian development pattern, and spawning ground data for red snapper 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. [ABSTRACT FROM AUTHOR]

The reproductive biology of red grouper Epinephelus morio from the inshore and offshore waters of the Yucatan Peninsula (Campeche Bank) was investigated over a 5-year period (1988-1993). Results confirmed that red grouper is a monandric protogynous hermaphrodite as shown by (1) the absence of primary males in samples, (2) the presence of transitionals in the population (1% of the total offshore catches), (3) the occurrence of a membrane-lined central cavity in the testes of all males and dorsal sinuses in the gonadal wall in most males, (4) the significant difference in size ranges and mean fork lengths of males and females, and (5) a female-biased male : female ratio in size-classes less than 72.0 cm fork length (FL). We found immature females all year round in inshore waters and immature females, mature females, and males, and transitionals in offshore waters. In the southern Gulf of Mexico, the species displayed seasonal reproduction, with single, annual peak spawning occurring in late winter and early spring (January-March). The greatest variations in the mean gonadosomatic index (GSI) of females were recorded between November (0.27%), February (2.14%), and April (0.17%) when they were ripening, ripe-running, or spent. Males were ripening between September and February, ripe-running from December through April, and spent in March. Spawning aggregations of red grouper were not observed. However, during the 1992 spawning period, 20 ripe-running females and 19 ripening and ripe-running males were caught near 20°47′N, 91°40′W on the western Campeche Bank on the second and fourth days after full moon. Sexual maturation in females occurred over a broad size range (38.9-72.0 cm FL). The size at first maturity, defined as length at which 50% of females were sexually mature ( L50), was 50.9 cm FL ± 1.2 (mean ±SE). Sex inversion in females did not occur at a particular size or at a precise time. Size range and median size at which females change sex were 41.0-85.4 cm FL and 59.7 cm FL, respectively. Transitionals were caught during 5 months of the year, including two peak spawning months (January and February). Fishery management implications are presented and discussed. [ABSTRACT FROM AUTHOR]