Table 1 — Observed mean lengths (mm), 

 weights (kg), and sample size by age for 

 Mycleroperca microlepis . 



Figure 2. — Schematic representation of a cross-sectioned gag 

 ovary (diameter = 3 cm). HS = halar stroma, L = lumen, 

 OL = ovarian lamellae, OW = ovarian wall, T = "Typhlosole- 

 type" invagination of the dorsal wall. 



lumena forming a common oviduct. The lumena 

 are incompletely lined with folded germinal ep- 

 ithelium (ovarian lamellae) within which oocytes 

 develop and mature. The ventral regions of the 

 lumena remain void of lamellae, and these 

 alamellar areas are contiguous with the alamel- 

 lar oviduct. In addition to the dorsal and lateral 

 walls of the lumena showing lamellar develop- 

 ment, there is a "typhlosole-type" continuation of 

 the dorsal gonad wall projecting into each lumen. 

 This projection of connective tissues into the cen- 

 ter of the lumen apparently allows additional sur- 

 face area for attachment of ovarian lamellae 

 (Fig. 2). 



During the sexual transition phase, testicular 

 growth fills the existing ovarian lamellae, dis- 

 placing and possibly dislodging the already de- 

 generating oocytes. Transitional gonads were 

 rarely found, and there were no cases of simulta- 

 neous development of gonad tissues. Male gonads 

 retain the somatic morphology of the ovary. Tes- 

 ticular tissue is arranged in "false lamellae", pri- 

 marily suspended from the "typhlosole-type" 

 structure. Sperm sinuses form peripherally in 

 what was previously the ovarian wall and con- 

 tinue posteriorly becoming the vas deferens 

 within the oviduct wall. The vestigial ovarian lu- 

 mena and oviduct remained in all testes exam- 

 ined. All testes also possessed many residual 



oocytes, some as large as 500 ixm in diameter. 



Females made up 849f of the gag which were 

 sexed. Examining the percentage in each age 

 class, we found that 28% of age III, 5V7c of age IV, 

 and all older female gag had mature ovaries. Im- 

 mature gag ranged from 290 to 680 mm TL, 

 whereas the smallest mature female was 600 mm 

 TL. Male gag accounted for 15% of the animals 

 sexed and were found in ages V through XX (no 

 sex available for age XXI and XXII fish). No 

 males were found smaller than 790 mm TL 

 (Fig. 3) and no juvenile males were found. Gag 

 with transitional gonads made up 1.25% of all the 

 groupers sexed and occurred in ages V through 

 XI. The size range for fish undergoing sex succes- 

 sion was from 750 to 950 mm TL (Fig. 3). 



The gag spawns once a year in late winter-early 

 spring. Analysis of the relative abundance of de- 

 veloping, ripe, and postspawned gonads indicated 

 that peak spawning activity was reached in late 

 March and early April (Fig. 4) in the SAB. 



Discussion 



Use of whole sagittae in aging gag has been 

 validated (McErlean 1963), and Matheson et al. 

 (1986) successfully validated the use of sectioned 

 sagittae to age the congeneric scamp, Myctero- 

 perca phenax . These studies together with the 

 present data provide good evidence that sagittal 



650 



