744 
Fishery Bulletin 96(4), 1998 
<u 
X> 
Estimated age (yr) 
Figure 6 
Age-frequency distributions for male and female black grouper, Mycteroperca 
bonaci, from South Florida waters. 
seasonal trend (Fig. 13). Testes from sexually mature 
males ranged in weight from 14 to 197 g and were much 
smaller overall than ovaries from sexually mature fe- 
males, which ranged in weight from 1 to 1354 g. 
Discussion 
We obtained black grouper from a variety of fishery- 
dependent and fishery-independent sources, and it 
is difficult to assess the extent to which the length 
and age structure of our sample reflects that of the 
population or the degree to which different fishing 
gears biased the various samples. Although we 
sampled grouper that were landed in two geographi- 
cally separate locations, the Florida Keys and in 
Pinellas County on Florida’s Gulf coast, most of the 
grouper landed in both locations were caught in the 
waters off the Florida Keys. Most of the large (>1000 
mm) fish and most of the males that we examined 
came from commercial fish houses on Florida’s Gulf 
coast, and most of these grouper were caught on the 
Tortugas Banks west of the Florida Keys. Fish ob- 
tained from Keys headboats, fish houses, and spear- 
fishermen were smaller and younger overall than 
grouper sampled from fish houses in Pinellas County 
(Fig. 2). Most black grouper landed in Pinellas 
County fish houses were caught with commercial 
longlines in depths greater than 37 m (20 fathoms); 
most of the fish landed in the Keys were captured by 
spear fishermen, principally in water 6-50 m deep. 
The greater depths fished and the greater distances 
traveled by Gulf-coast commercial fishermen to pre- 
sumably more remote fishing areas probably account 
for the differences between the two samples. 
Age and growth 
Black grouper appear, on the basis of marginal-in- 
crement validation for grouper 1-7 years old, to form 
a single annulus each year in late spring or early 
summer. We were unable to validate that annuli are 
annual marks in older grouper, and the accuracy of 
our age estimates for older fish is unknown. The 
annuli we counted on otolith sections from older grou- 
per were similar in appearance to validated annuli; 
