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Fishery Bulletin 96(4), 1998 
Age (yr) 
Figure 8 
Logistic curves describing the percentage of female black grouper, Mycteroperca bonaci, 
collected from South Florida waters that were sexually mature and the percentage of our 
black grouper Sample that was made up by females as a function of both total length (mm) 
and age (years). M- 0 is the length or age predicted by the logistic regression at which 50% 
of the female black grouper were sexually mature, and P 50 is the length or age predicted by 
the logistic regression at which 50% of the black grouper in our sample were females. 
olds. When we recalculated growth models with CV 
thresholds of 10% and 5%, our estimates of L o and K 
remained within two standard errors of the estimates 
at a CV of 12%, but the numbers of otoliths elimi- 
nated from our analysis increased substantially at 
lower CV thresholds. 
The two oldest black grouper in our sample were 
both estimated to be 33 years old, considerably older 
than Manooch and Mason’s ( 1987) oldest grouper ( 14 
years). Manooch and Mason sampled hook-and-line- 
caught black grouper from Keys headboats during 
1978-85 and speculated that the maximum age at- 
tained by black grouper was probably about 19 years. 
The presence of older fish in our sample is probably 
because our sample contained black grouper that 
were larger (largest 1518 mm) than those examined 
by Manooch and Mason (largest aged 1180 mm; larg- 
est measured 1259 mm). We measured 125 black 
grouper longer than 1200 mm and aged 94 of these. 
Of the 98 grouper that we estimated to be older than 
14 years, 84% were longer than 1200 mm and were 
longer than any fish aged by Manooch and Mason. 
Most of the large black grouper in our sample were 
caught by commercial longliners and landed in 
Pinellas County; the lengths and ages of the grouper 
in our sample that were landed in the Keys were simi- 
lar to those of Manooch and Mason (1987). 
Our estimates of length at age are similar to those 
of Manooch and Mason (1987), and the predicted 
growth curves from both data sets are in general 
agreement (Fig. 14). In some cases, such as age 
classes 5-9, our estimates of mean length at age are 
