Newman et al.: Variability in the population structure of Lutjanus adetii and L quinquelineatus 



319 



other reefs, older year classes were relatively domi- 

 nant at KL. JB and RI had relatively flat age distri- 

 butions for year classes 2-24 compared with those 

 for LO, DV, and MR. The only pattern that was con- 

 sistent across all reefs was the strong mode of 5-year- 

 old individuals (Fig. 3), and this may have reflected 

 the age at which these fish attained full recruitment 

 to the sampling gear (fish traps). 



Growth models 



The von Bertalanffy models of the length-age rela- 

 tionship among reefs for L. adetii are shown in Fig- 

 ure 4; the coefficients of determination among reefs 

 ranged from 0.177 to 0.462. The low coefficients of 

 determination were attributable to the absence of 

 younger and smaller fish in the samples. Therefore 

 no point of inflexion was evident in the growth mod- 

 els among reefs. As a result, the parameters of the 

 von Bertalanffy models for L. adetii among individual 

 reefs were characterized by large asymptotic stan- 

 dard errors (Table 5), with LO having the best-fit- 

 ting model. The von Bertalanffy model from LO was 

 similar to that derived from all reefs pooled within 

 the central Great Barrier Reef (Table 5). Despite the 

 absence of small and younger fish caused by the bias 

 in sampling, the von Bertalanffy growth function was 

 the best empirically based assessment of growth in 

 L. adetii (Fig. 4). The von Bertalanffy growth curves 

 for L. adetii were not significantly different among 

 reefs (likelihood-ratio test, P»0.05; ARSS:F=1.13, 

 P»0.05), and the resulting growth curves (Fig. 4) 

 appeared to be similar. Additionally, there were no 

 significant differences in the mean length (FL) of the 

 early age classes (6+, 7+, 8+, and 9+) of L. adetii 

 among reefs (Table 6). 



The von Bertalanffy model provided a better de- 

 scription of the length-age relationship among reefs 

 for L. quinquelineatus (Fig. 5), with coefficients of 

 determination among reefs ranging from 0.267 to 

 0.752. The younger and smaller fish were under- 

 represented in the catch samples from some reefs 

 and this was reflected in the coefficients of determi- 

 nation (Table 5; Fig. 5). The parameters of the von 

 Bertalanffy models for L. quinquelineatus among 

 individual reefs were characterized by relatively 

 small asymptotic standard errors (Table 5). The growth 

 curves for L. quinquelineatus were significantly differ- 

 ent among reefs (likelihood-ratio test, P<0.01; 

 ARSS :F=8.401, P<0.001 ). Differences among reefs were 

 observed in values of L c ,, K, and t Q (Table 5). However, 

 there were no significant differences in the mean length 

 (FL) of the early age classes (2+, 3+, 4+, 5+, and 6+) of 

 L. quinquelineatus among reefs (Table 7). 



Analysis of covariance (ANCOVA) demonstrated 

 that the relationship between weight and length in 

 L. adetii was significantly different both among reefs 

 and between sexes and that the among-reef differ- 

 ences were independent of the sex of the fish (Table 

 8). Similarly, ANCOVA demonstrated that the rela- 

 tionship between weight and length in L. quin- 

 quelineatus was also significantly different both 

 among reefs and between sexes (Table 8). However, 

 the significant among-reef differences were not inde- 

 pendent of the sex of the fish (a significant interaction 

 effect occurred between reefs and sex). The differences 

 among reefs were different for each sex ( Table 8 ). 



Mortality 



In general, individual L. adetii less than 7 years of 

 age did not appear to be fully recruited in the sampled 



