KILLAM and PARSONS: AGE AND GROWTH OF THE BLACKTIP SHARK 



Bertalanffy gi'owth equation fit with observed 

 data. Growth curves for both sexes were signifi- 

 cant at P < 0.05. Growth equations produced for 

 female and male C. li»ibatns were 



Female: L, = 195.0 (1 - exp" i»'"^ii5)) 

 r = 0.987, TV = 80 



Male: L, = 166.5 (1 - expO-^'+o.ss)) 

 )■ = 0.979, N = 53. 



Estimated maximum total length of females 

 was significantly different from males as indi- 

 cated by the separation of the calculated 95% 

 confidence intervals. K values, although larger 

 for males, were not significantly different from 

 females {Table 2); however, females were signifi- 

 cantly larger than males after age seven (Stu- 

 dent's f-test, P < 0.05). 



Growth rates for juvenile, adolescent, and ma- 

 ture blacktip sharks were approximately 19-21, 

 9-10, and 3-4 cm/yr, respectively. Females 

 matured at 158-162 cm at 6-7 years; males ma- 



Table 2. — Estimated parameters of the von Bertalanffy growtti 

 equation derived using SAS nonlinear method, including 95% 

 confidence intervals. 



Asymptotic 95% 

 confidence interval 



Parameter 



Estimate 



Lower 



Upper 



Females 

 L,(cm) 

 K 



Wyr) 



Males 

 L,(cm) 

 K 



195.0 

 0.1967 

 -1.154 



166.5 



0.2758 



-0.8836 



183.0 

 0.1546 

 -1.555 



155.0 



0.2066 



-1.3006 



206.9 

 0.2393 

 -0.753 



177.9 



0.3450 



-0.4665 



tured at 133-136 cm at 4-5 years (Killam 1987, 

 Figs. 6, 7). The smallest gi-avid female captured 

 was six years old. Maximum age obtained by 

 female C. linibatus was 10 years for two fish 

 which measured 179.0 and 180.0 cm. Maximum 

 age of male C. lit)ibatHs was nine years for a fish 

 which measured 160.5 cm. 



160 



_ 140 



Z 



< 



o 



100 



80 



60 - 



• - OBSERVED 



 PREDICTED 



O BACK CALCULATED 



O 



MALE 



0.276 (f0.881) 



L^- 166.5 (1-e 



r .9791 

 n'53 



0123456789 



ESTIMATED AGE (years) 

 B23456789 10 



NUMBER OF RINGS 



Figure 7. — Von Bertalanffy growth curve foi- male blacktip sharks fit from observed data. Distance between 

 ring B and ring 1 is only 7-8 months but is represented as a 1-yr interval to prevent overestimation of early 

 growth rates. 



851 



