470 



Fishery Bulletin 101(3) 



n Resting Ripening  Ripe-running H Spent 



100 



80 



60 



40 



20 



62 101 88 66 64 50 29 



i 



ii 



rnif 



18 54 59 35 



i! 



^1 



i 



I 



B 



100 

 80 

 60 

 40 

 20 

 



Sep Oct Nov Dec Jan Feb Mar Apr l^ay Jun Jul Aug 



D Resting Q Ripening  Ripe-running Ca Spent 



23 34 28 26 10 9 5 1 12 26 27 13 



I 



ill 



8 1 



III 



I 



u 



I 



Sep Oct Nov Dec Jan Feb Mar 

 Montti 



Apr May Jun Jul Aug 



Figure 5 



Monthly percent frequencies of female (A) and male (B) 

 black grouper iMycteroperca honaci) collected in offshore 

 waters of the Campeche Bank, Mexico (April 1996-May 

 1999), sorted according to sexual classes over one year. 

 Number offish sampled is given for each month. 



grouper sampled from Florida waters may not resemble 

 that for the entire population. Crabtree and Bullock ( 1998) 

 stated that they probably underestimated the number of 

 males in their sample because the large black grouper ex- 

 amined were eviscerated and could not be sexed. . 



As observed for the first time by Crabtree and Bullock 

 ( 1998) for black grouper from Florida waters, sexual dimor- 

 phism was displayed by the Campeche Bank population. 

 Notwithstanding, a low proportion of females possessed fin 

 pigmentation. Furthermore, it is also possible that indi- 

 viduals undergoing transition from female to male display 

 the male color phase. However, conclu.sions based on differ- 

 ences in fin pigmentation in male, female, and transitional 

 black grouper from the Campeche Bank are limited by the 

 small number of specimens examined for this purpose. 



Spawning season 



Sexually active black groupers from the Campeche Bank 

 (ripening females and ripening or ripe-running males) 

 were observed year-round. The monthly relative propor- 



Figure 6 



Photomicrographs of histological sections from female 

 black grouper iMycteroperca bonaci) gonads collected from 

 Campeche Bank, Mexico. (A) Section from a 97-cm-FL 

 ripe-running female captured in January 1998, showing 

 late vitellogcnic oocytes (stage V) undergoing final oocyte 

 maturation, showing yolk and oil globule fusion and germi- 

 nal vesicle migration; note presence of postovulatory follicle. 

 (B) Section from a 79-cm-FL ripe-running female captured 

 in February 1998, with hyaline oocyte (stage VI) and some 

 early and late vitellogenic oocytes (stages III and IV). (C) 

 Section from a 92-cm-FL ripe-running female captured in 

 November 1997, with early and late vitellogenic oocytes 

 (stages III and V) and postovulatory follicles. EVO = early 

 vitellogenic oocyte; GV = germinal vesicle; HO = hyaline 

 oocyte; LVO = late vitellogenic oocyte; OG = oil globule; PO 

 = prcvitellogenic oocyte; PDF = postovulatory follicle; YG = 

 yolk globule. Scale bars = 200 microns. 



tion of individuals in each sex class and mean gonadoso- 

 matic indices showed a more consistent annual cycle for 



