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Fishery Bulletin 101(3) 



50% or more of the sampled females have yolked oocytes. 

 Peak spawning occurred in February when 50"^ or more of 

 the sampled females had hyaline oocytes or postovulatory 

 follicles (or both) in their ovaries. In the case of spawning 

 seasonality evaluated by GSI data, peak spawning activity 

 was assigned to the months of January and February in 

 which the mean GSI of female attained was SOVr or more of 

 the maximum mean female GSI recorded during the study 

 (2.20% in February). A very few precocious females started 

 to spawn in October (1% of sampled fish) and November 

 (3'/i) and some were still in spawning condition during 

 May (4%) and June (8%). These results are consistent 

 with previous reports of the M. bonaci spawning season 

 in Puerto Rico, the Bahamas, Cuba, and Florida (Erdman, 

 1956; Smith, 1961, 1971, 1972; Garcia-Gagide et. al., 1994; 

 Garcia-Gagide and Garcia, 1996; Crabtree and Bullock, 

 1998). Spawning in Bermuda appears to be anomalous, 

 with reproductive activity extending from about early May 

 to early August ( Smith, 1971). 



Spawning pattern 



The authors did not observe spawning aggregations for 

 black grouper from the Campeche Bank as defined by 

 Domeier and Colin (1997) for tropical reef fishes. Black 

 grouper is reported to form spawning aggregations 

 between January and February in Belize, Honduras, and 

 Florida (Carter, 1989; Fine, 1990; Carter and Perrine, 1994; 

 Eklund et al., 2000). Only indirect methods of establishing 

 spawning occurrence, based on female gonadal condition, 

 were used in the present study. Ripe-running females were 

 caught at 11 offshore locations on the Campeche Bank and 

 in the shallow waters of National Marine Park Alacranes 

 Reef, during eight months of the year. The species seemed 

 to spawn preferentially at or around the new moon phase. 

 However, more information, such as direct observations of 

 spawning behavior and data on fish densities at aggrega- 

 tion sites during nonreproductive and reproductive periods, 

 is necessary to know precisely where and when adult M. 

 bonaci gather for spawning in the southern Gulf of Mexico. 

 The presence of oocytes at various stages of vitellogenesis 

 in the ovaries of ripening females and the co-existence of 

 postovulatory follicles and vitellogenic oocytes in those of 

 ripe-running females suggest that some individuals may 

 spawn more than once during the spawning season. 



Sexual maturity and sex ciiange 



The size at which 50% of females were sexually mature 

 (Lr,Q) was lower for black grouper from the Campeche Bank 

 (72.1 cm I than for those from Florida (82.6 cm) or Cuban 

 (84.4-108.7 cm) waters. The L„„„/L„,,,^ ratio indicated 

 that the females from the Campeche Bank reached first 

 maturity at a higher proportion of maximum length (47%) 

 than those from Florida waters (40% I. This spatial varia- 

 tion in size at first sexual maturity has also been observed 

 in female red grouper from southern and eastern Gulf of 

 Mexico (Brule et al., 1999). 



The size at which 50% of the females transformed to 

 males (P5Q) was lower for black grouper from the Campeche 



Bank (111.4 cm) than for those from Florida (119.9 cm). 

 Notwithstanding, the size range in which males overlapped 

 with females and the ratio-2 results were almost identical 

 for black grouper from Campeche Bank (39.5 cm and 29%) 

 and south Florida (39 cm and 26%) waters (Crabtree and 

 Bullock, 1998). According to Shapiro ( 1987), these data are 

 more consistent with a mechanism for behavioral induction 

 of sex change than with the idea that this process occurs at a 

 characteristic size or age for all members of a population. 



Fisliery ciiaracteristics and fisliery management 



As members of the warm-temperate and tropical reef 

 fish complexes, groupers have consistently proven highly 

 vulnerable to anything other than light levels of fishing 

 pressure (Sadovy, 1997). Because of their biological char- 

 acteristics, these species must be conservatively managed 

 to avoid rapid overfishing and stock collapse ( Sadovy, 1997; 

 Coleman et al., 2000). Some groupers from the western 

 Atlantic are even considered endangered and threatened 

 species (lUCN/SSCi). Assessment of Morris et al. (2000) and 

 Musick et al. (2000) led to the classification of black grouper 

 as a vulnerable species, that is, not critically endangered, 

 endangered, or threatened severely, but facing a high risk 

 of extinction in the wild in the medium-term future. 



The trend in grouper catches in the state of Yucatan 

 has been one of progressive decline from an historical 

 maximum of 13,993 metric tons (t) in 1991, to 8556 t in 

 1997, followed by an increase to 11,045 metric tons in 

 2000 (SAGARPA, 2001). According to Monroy-Garcia et 

 al. (2001), catch increase reflects an increase in fishing 

 effort during the last three years. Recent assessments of red 

 grouper population from the Campeche Bank indicate that 

 the current biomass of exploited stock is well below that 

 of maximum biological productivity and that the fishery is 

 considered deteriorated (SEMARNAP, 2000a, 2000b). In 

 response to the multiple threats facing groupers in the Gulf 

 of Mexico, the U.S. and Mexican governments have imple- 

 mented regulations designed to either reduce or contain 

 effective fishing effort (input controls), or to restrict total 

 catch (output controls) to predefined limits. Notwithstand- 

 ing, grouper fishery regulations used in Mexican waters are 

 less restrictive than those imposed in U.S. waters. The U.S. 

 regulations currently consist of the following: an annual 

 commercial quota of 4445 t for the shallow-water grouper 

 complex, which includes the black grouper; commercial and 

 recreational minimum size limits of 61.0 cmTL and 55.9 cm 

 TL, respectively; a seasonal closure on commercial harvest 

 and prohibition on sale of this species from 15 February to 

 15 March; and a recreational aggregate daily bag limit of five 

 groupers per person (Gulf of Mexico Fishery Management 

 Council^). The Mexican regulations include license limita- 



' 2001. lUCN/SSC (International Union for the Conservation of 

 Nature and Natural Resources/Species Sur\'ival Commission). 

 SSC Red Li.st ProRramme lUCN/SSC UK Office, 219c, Hunting- 

 don Road, Caml)rid},'e CB3 ODL, United Kingdom. Web page: 

 http://www.rodlist.org 



'■^2001. GulfofMcxico Fishery Management Council. The Com- 

 mons at Rivcrgate, 3018 U.S. Hwy. 301 N., Suite 1000 Tampa, 

 Florida 33619-2266. Web page: http://www.gulfcouncil.org 



