Ferreira and Russ: Age-validation and growth rate of Plectropomus leopardus 



Figure 4 



Sectioned otolith of a recaptured individual coral trout, P. leopardus In" 0057) 

 rescent band. Scale Bar = 0.25 mm 



showing fluo- 



When fitting Schnute's model to both sets of data, 

 the value of the parameter b was very close to 1. In 

 the boundary where 6 = 1, the curve was reduced 

 to a three parameter model that corresponds to the 

 von Bertalanffy curve for length (Schnute, 1981). 

 The resulting growth model for all age classes, in 

 the form of a von Bertalanffy model, was 



L, =52.2 (1-e- 0.354(^ + 0.766)) r = 0.895 (Fig. 8). 



Table 2 



Von Bertalanffy growth parameters V.B. and re- 

 spective standard errors (SE), correlation coeffi- 

 cients (r 2 ) and degrees of freedom (df) for the 

 growth curve fitted to all data and to the data for 

 coral trout, P. Leopardus, >2 year old only. 



(SE) 



K 



(SE) 



(SE) 



df 



V.B. 

 all ages 



V.B. 

 age >2+ 



52.20 

 (0.768) 



0.354 

 (0.0241 



61.29 0.132 

 (3.483) (0.030) 



-0.766 

 (0.097) 



-4.660 

 (1.024) 



0.895 310 



622 272 



The results obtained when fitting the growth curve 

 to all data and to the data for fish >2+ years old only 

 were quite different (Table 2). From age-2 onwards, 

 the growth rate is much slower than the one esti- 

 mated by using all age classes, as indicated by the 

 growth coefficient K. Consequently, the estimated L m 

 is larger and the estimated t o is a very large, nega- 

 tive value. The resulting growth model was 



L, =61.29 (l-e-0.132(f + 4.66)) r = 0.622 (Fig. 9). 



No systematic trend in the residuals was observed 

 (normality test P>0.1) (Figs. 8 and 9). 



The relation between fork length (FL) and the 

 standard length (SL) was 



SL = -0.308 + 0.852 * FL, r 2 = 0.994, 



and the relationship between FL and Total Weight 

 (TW) was 



TW = 0.0079 *FL 



3 157 



0.967. 



Discussion 



While some comparisons between readings of whole 

 and sectioned otoliths have indicated good agree- 



