64 
Fishery Bulletin 107(1) 
0 5 10 15 20 25 .50 35 40 45 50 55 60 65 70 
Age (years) 
Figure 3 
Length- and age-frequency distributions for the 
western blue groper (Aehoerodus gouldii) caught 
by spear fishing (open histograms) and com- 
mercial gill netting (gray histograms). n s and 
n a , represent the number of fish caught by spear 
fishing and gill netting, respectively. 
are reflected in a lower estimate for k for males 
(0.08/year) than for females (0.12/year), and in 
a reverse situation for L x , for which the respec- 
tive values were 975 for males and 748 mm for 
females (Table 1). 
When von Bertalanffy growth curves were 
fitted separately to the lengths at age of those 
individuals that were either green or blue, but 
that constituted the same subset of fish as those 
just used to describe the growth of males and fe- 
males (Fig. 4B), the values for L „ and k for blue 
and for green fish were either identical or very 
similar to those for females and males, respec- 
tively (Fig. 4C; Table 1). Von Bertalanffy growth 
curves were next fitted to the lengths at age of 
fish, determined as females and males by using 
their gonadal characteristics (i.e., those used for 
Fig. 4B), and to the lengths at age of fish that 
could not be sexed by using gonads but could be 
assigned a sex on the basis of the combination of 
Figure 4 
Von Bertalanffy growth curves fitted to the lengths at age of (A) 
all sexed and unsexed individuals, (B) females (open circles) and 
males (black circles) sexed on the basis of their gonadal character- 
istics, (C) the same individuals as in (B) but separated according 
to whether they were green (open circles) or blue (black circles), 
and (D) for females (open circles) and males (black circles), for 
which the sex of each individual had been designated by using 
either its gonadal characteristics or the probability of it being 
female or male on the basis of a combination of its body color 
and length, n = sample size. 
