314 
Fishery Bulletin 1 12(4) 
30 -j 
| Female 
150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1150 
Total length (mm) 
Figure 2 
The total lengths, measured in millimeters, of female (black bars) and male (gray bars) dusky 
groupers (Epinephelus marginatus ) caught at Carpinteiro Bank in the southwestern Atlantic 
(«=189) by small-scale fisheries from 2008 to 2011. 
by the same person. Statistical analysis was conducted 
through a one-way analysis of variance after verifica- 
tion of the assumptions of normality and homoscedas- 
ticity (Zar, 1999). 
Results 
The TL of the dusky groupers sampled at Carpinteiro 
Bank ranged from 150 to 1160 mm TL (Fig. 2), and 
80% of all samples measured between 300 and 700 mm 
TL. Females (n=200) accounted for the vast majority of 
samples, whereas males (n=ll) composed only 5.5% of 
all samples. As expected, the mean TL for males (890.2 
mm TL [standard deviation (SD) 122]) was larger than 
the mean for females (512.1 mm TL [SD 152.9]). The 
length-weight relationship was WT = 0.00001 x TL 3 094 
(coefficient of determination [r 2 ]=0.985), and the al- 
lometric coefficient was significantly different from 3 
(t-test: P<0.0003), revealing that the species grows a 
little more in weight than in length. 
The opaque and translucent growth bands in the 
otoliths of the dusky grouper were reasonably discern- 
ible, resulting in fine levels of precision during the pro- 
cess of otolith reading (APE=6.9%, ;i=211). Of the 211 
examined otoliths, 22 were excluded from the analysis 
because of the absence of agreement among readings 
and 188 and 189 were used to validate the timing of 
deposition of growth increments and to estimate aging 
structure and growth, respectively. 
The mean distribution of marginal increments in 
otoliths had significant differences among the fish 
collected during the 4 seasons (Kruskal-Wallis test: 
P<0.03; Fig. 3A). Marginal increment values were sig- 
nificantly lower during the winter than during the 
spring and summer (Mann-Whitney test: P<0.005 and 
P<0.018, respectively), and this pattern of differences 
was the same as the one observed for the proportion of 
opaque bands in the otolith edges (Fig. 3B). The same 
pattern was obtained for mean SST, where the propor- 
tion of opaque bands at the otolith edges was positively 
correlated with SST (r 2 =0.841). 
Ages ranged from 1 to 40 years, and 85% of samples 
were aged between 2 and 8 years (Table 1). The mean 
ages for males and females were 26.7 years (SD 6.3) 
and 6.1 years (SD 4.9), respectively. The youngest sam- 
pled male was 20 years old and measured 760 mm TL, 
whereas no females were found at ages of more than 
27 years or lengths greater than 933 mm TL. The von 
Bertalanffy parameters that were estimated for pooled 
sexes (n=189; L oo =900.9 mm TL, K=0.129, tQ--lAb 
years) showed smaller values for L,_„ and larger values 
