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Fishery Bulletin 97(1), 1999 



Our growth coefficient is similar to that found by 

 Cailliet et al. ( 1985), and both are an order of magni- 

 tude lower than that of 7. oxyrinchus at 0.203-0.266 

 (Pratt and Casey, 1983) and that oiLamna nasus at 

 0.116 (Aasen, 1963). In the first year of growth, C. 

 carcharias grows 19-26% of its size at birth which is 

 less than that of other lamnoids (Branstetter, 1990). 

 Our findings place C. carcharias in Branstetter's 

 (1990) group of sharks with slow growth (/?<0.10; 

 growth in the first year<30% of the birth size). 



In our study, back-calculated size at birth was 100 

 cm and calculated value was 135 cm. The smallest 

 accurately measured free-swimming C. carcharias 

 in southern Africa was 108 cm (140 cm TL) (Smith, 

 1951) and the sizes of the smallest white sharks 

 caught at the NSB are 128-145 cm. "Umbilical scars" 

 (Cliff et al., 1996a) were present in sharks of 138, 

 143, 144, and 145 cm, including the 131 cm (0 GR) 

 specimen of this study. If the presence of these scars 

 is interpreted as an indication of recent birth, it is 

 tempting to suggest a very wide range in size at birth, 

 between 100 and 145 cm. These scars, however, may 

 persist for some time after birth and given a growth 

 of about 25 cm/yr in newborn sharks, birth size of C. 

 carchirias would be more in the region of that re- 

 ported by Francis (1996), i.e. 92-116 cm (120-150 

 cm TL). Our range in mass at birth (22-54 kg) is 

 also substantial, which is in keeping with Francis 

 ( 1996 ) who stated that the range in mass at birth for 

 C. carcharias is quite pronounced. 



Our three mature males had 8, 10, and 13 GRs 

 (293, 317, and 373 cm; 371, 544, and 882 kg, respec- 

 tively). The NSB has caught immature specimens 

 larger and heavier than our smallest mature, e.g. a 

 295 cm (420 kg) and a 306 cm (442 kg) specimen (Cliff 

 et al., 1996a). Pratt's (1996) smallest mature male 

 was 299 cm (379 cm TL), which is similar to our 

 shark; however, he notes that sizes at sexual matu- 

 rity for male C. carcharias vary widely in the litera- 

 ture. These differences could be due to a variation in 

 length at maturity depending on location, both com- 

 pounded by the use of different length conversion 

 equations and maturity criteria. If the number of GRs 

 is taken as an age estimate, assuming annual GR 

 deposition, male C. carcharias in South Africa would 

 mature between 8-10 years which is similar to the 

 findings of Cailliet et al. (1985) who worked with a 

 size at maturity of 313-365 cm (366-427 cm TL), 

 corresponding to an age of 9-10 years. This age at 

 maturity is higher than that of other lamnids, e.g. 

 that of male I. oxyrinchus at 2-3 years (Pratt and 

 Casey, 1983) and male L. nasiis at about 5 years 

 (Paust and Smith, 1986). 



No mature female has ever been examined from 

 NSB nets, and the biggest female in our study was 



297 cm (6 GRs). The biggest female on record is an 

 immature 348 cm specimen (Cliff et al., 1989), and 

 Bass et al. (1975) reported a mature female of 352 

 cm (445 cm TL). Again if GRs are deposited annu- 

 ally, the above specimens would be 11 and 12 years, 

 respectively. Age at maturity for female C. carcharias 

 in South Africa would then be at least 12-13 years, 

 slightly higher than that for males. Again, this age 

 at maturity is higher than in other lamnids, e.g. that 

 for female /. oxyrinchus at 7 years (Pratt and Casey, 

 1983) and female L. nasus at 9-10 years (Paust and 

 Smith, 1986). 



Although this study could not conclusively prove 

 annual or biannual GR periodicity, the recapture of 

 one shark injected with OTC provided some evidence 

 for annual GR deposition. Assuming that only one 

 growth ring is laid down per year, then C. carcharias 

 from South Africa is relatively slow growing in com- 

 parison with other lamnoids. This observation would 

 support current protective legislation. The NSB nets 

 are now the only directed source of apparent fishing 

 mortality for C. carcharias in South Africa. Cliff et 

 al. ( 1996b ) were of the opinion, using their estimates 

 of mortalities, that the current fishing mortality did 

 not represent overfishing of the white shark stock. 

 Examination of interannual catch rates of C. 

 carcharias in the NSB nets showed an significant 

 decline immediately following the introduction of 

 netting, but thereafter (1978-93) there was no sig- 

 nificant change (Cliff et al., 1996a). Because they are 

 apex predators, C. carcharias are likely to have a 

 small population size (Cliff et al., 1996b), and we have 

 no knowledge about the fecundity and nursery 

 grounds of this species in South African waters. Any 

 possible relaxation of the South African current leg- 

 islation will depend on improved knowledge about 

 population size, immigration and emigration, natu- 

 ral mortality, and fecundity of C. carcharias from 

 South Africa. 



Any such relaxation, however, is highly unlikely 

 given the increasing protection that has been granted 

 to this species worldwide. It is now also protected in 

 some states of America (Fergusson et al., in press) 

 and Australia (StevensM, where such legislation is 

 based on a more limited knowledge or understand- 

 ing of the biology and papulation dynamics of this 

 species. 



Acknowledgments 



The assistance of the field staff of the NSB, who pro- 

 vided specimens and associated information, is 

 greatly appreciated. The laboratory staff was respon- 

 sible for dissecting many sharks and for collecting 



