400 



Fishery Bulletin 90(2), 1992 



E 

 E 



C 



400 



300 



200 



100- 



400 



300- 



E 

 E 



en 



c 



200 



100 



Females 



— I — \ — I — I — I — I — I — I — I — I 

 01 23456789 10 



Age (years) 



Figure 8 



Growth of male and female Lutjanus vittus assigned an ab- 

 solute age assuming a 1 January birthdate. 



o 

 n) 



E 



o 



■c 

 o 

 a. 



1.0 



0.8 - 



0.6 



0.4 



0.2 



0.0 



t£) CVJ [^ Ifi^ 



100 



200 

 Length (mm) 



300 



400 



Figure 9 



Proportion of males by 10 mm length-class. Means, 95% 

 binomial confidence limits (vertical lines), and sample size are 

 plotted. 



were used in this analysis. Both males and females 

 grow at the same rate for the first three years, after 

 which females grow at a markedly slower rate than 

 males. 



Sex ratio 



There was a marked departure from a 1:1 sex ratio 

 (Fig. 9; likelihood ratio x' 152.1, df 29, P<0.001) 

 which can be attributed to different growth rates be- 

 tween the sexes. Below 300 mm, sex ratios did not dif- 

 fer from 1:1 (likelihood ratio x" 23.3, df 18, P 0.18) but 

 in all larger size groups there was a predominance of 

 males. 



Length-frequency 

 distributions 



Length-frequency distributions of 

 the population were determined 

 separately for males and females 

 (Fig. 10). Each length-class was 

 separated into age-classes based 

 on the urohyal data. There was 

 a jump in age-class between sam- 

 ples taken in August and October 

 because a new check was formed 

 in the intervening period. While 



