818 



Fishery Bulletin 98(4) 



Age (years) 



Figure 6 



Length-at-age plots for (A) male, (Bl female. (Ci injected. (Di noninjected. and (E) all Car- 

 charhinus ohscurus from southwestern Australia. Lines represent linear gi-owth functions 

 based on parameters given in Table 4. 



Despite the difficulties in obtaining von Bertalanffy 

 growth parameters with the Fabens (1965) method, the 

 growth rates from age zero to 5 years were similar to those 

 from the linear growth function from the Francis (1988) 

 and length-at-age methods (Fig. 7). Each of the methods 

 indicates that on average juvenile C. ohscurus grow 8-11 

 cm/year. The results from the current study (for all meth- 

 ods) were also similar to those from previous studies for 

 C. ohscurus in the western North Atlantic and southwest- 

 ern Indian Ocean by Natanson et al. (1995) and Natan- 

 son and Kohler (1996), respectively (Fig. 7). However, the 

 growth rates were lower than those suggested by Brans- 



tetter (1990) who used data from Schwartz (1983) to esti- 

 mate the growth rate of C. ohscurus pups from the western 

 North Atlantic to be approximately 15 cm/year. At ages 

 greater than five years, the gi-owth rates estimated by 

 the current study corresponded poorly to obsei-ved results 

 in other studies. This is a result of the linear growth of 

 the juveniles that does not predict the decrease of growth 

 rates as individuals age. Extrapolation of the results to 

 ages greater than five years is thus invalid and should be 

 avoided. 



The results of the Francis (1988) method indicate a rela- 

 tively high level of growth variation in juvenile C. obscu- 



