750 
Fishery Bulletin 96(4), 1998 
n =300 
673 mm TL 
oM IWlff 
Tn m a 
: 1 n ["I 
Oocyte diameter (mm) 
Figure 12 
Oocyte diameter (mm) frequency distributions for six hydrated female black grouper, Mycteroperca 
bonaci , from South Florida waters. Hydrated oocytes were 0.8-1. 2 mm in diameter. Only oocytes with 
diameters larger than 0.2 mm were measured, n = the number of oocytes measured. 
Seasonality of gonad development 
Reproduction in black grouper was seasonal, with 
peak gonad development during December-March, 
but females with vitellogenic oocytes were present 
during all months and females with elevated GSIs 
occurred in most months. In Cuban waters, Garcia- 
Cagide and Garcia ( 1996) also found that black grou- 
per spawn during winter and spring. Other eastern 
Gulf of Mexico grouper species have similar seasonal 
patterns of gonad development, and in several spe- 
cies, the spawning season appears to be prolonged. 
In gag, gonad development occurs during December- 
May, and peak gonadal activity occurs during Feb- 
ruary and March (Hood and Schlieder, 1992). Yellow- 
mouth grouper gonads are active throughout the 
year, and peak gonadal activity occurs during April- 
May (Bullock and Murphy, 1994). Jewfish have de- 
veloped gonads from June-December, with peak ac- 
tivity during July-September (Bullock et al., 1992). 
Yellowedge grouper gonads are developed during 
January-October, with peak activity during May- 
September (Bullock et al., 1996). 
Many grouper species are known to form seasonal 
spawning aggregations at specific times and locations 
each year (Sadovy, 1994). Aggregations of black grou- 
per have been reported off Central America during 
January and February (Carter, 1989; Fine, 1990; 
Carter et al., 1994), the same time of year that we 
observed peak gonadal development and the great- 
est incidence of oocytes in the final stages of matu- 
ration. Among other species of Mycteroperca , aggre- 
gations of gag and scamp have been reported 
(Gilmore and Jones, 1992), and spawning by an ag- 
gregation of tiger grouper, M. tigris, was reported by 
Sadovy et al. ( 1994a). Spawning aggregations of black 
grouper have not been documented in Florida wa- 
ters, but it is clear from the presence of oocytes in 
the final stages of maturation in our sample that 
spawning black grouper are landed in South Florida. 
Whether black grouper form spawning aggregations 
in Florida waters and the extent of these aggrega- 
tions is unknown. 
