153 



Abstract.— Ages of white sharks, 

 Carcharodon carcharias. from the east 

 coast of South Africa were estimated by 

 counting growth rings (GRs) in verte- 

 bral centra and relating them to length 

 and mass. The vertebrae of 61 females 

 (128-297 cm precaudal length (PCL)) 

 and 53 males (142-373 cm PCL) were 

 examined. Mass range was 42-442 kg 

 for females (n=60) and 46-882 kg for 

 males (n=53). X-radiography was used 

 to enhance the visibility of the GRs in 

 whole centra. Counts were made di- 

 rectly from the x-radiographs by one 

 reader and from scanned x-radiographs 

 by two readers. Count precision for each 

 method and reader was determined by 

 using the average percentage error (APE ) 

 index which ranged from 5.3 to 6.1'7c. 



One shark injected with oxytetracy- 

 cline (OTC) was recaptured after 942 

 days at liberty. The shark was tagged 

 at 140 cm and 46 kg and grew 69 cm 

 and 104 kg. The OTC was visible in the 

 vertebra and there was evidence of 

 annual growth ring deposition. This 

 could, however, not be confirmed with 

 centrum analyses of the entire sample. 



The number of GRs counted varied 

 in the following manner. The female 

 and male with the lowest number of 

 GRs, had GR ( 131 cm PCL) and 1 GR 

 (142 cm PCL), respectively. The female 

 and male with the highest number of 

 GRs, had 8 GRs (282 cm PCL) and 13 

 GRs (373 cm PCL). respectively The 

 smallest mature male had 8 GRs (293 

 cm PCL); there were no mature fe- 

 males. Von Bertalanffy parameters for 

 the combined sexes were L^ = 544 cm 

 PCL, k = 0.065/yr, t^ = -4.4 yr. Growth 

 calculated from predicted lengths de- 

 creased from 26 cm for sharks with 1 

 GR to 12 cm for sharks with 13 GRs. 

 Gompertz parameters were Wg = 54 kg, 

 G = 3.94, g = 0.094/yr Growth calcu- 

 lated from predicted mass increased 

 from 23 kg (1 GR) to 94 kg (13 GRs). 

 Back-calculated lengths and mass were 

 lower than observed values and Lee's 

 phenomenon was evident in both back- 

 calculated lengths and mass but not 

 consistentlv. 



Age and growth determination of the 

 white shark, Carcharodon carcharias, 

 from the east coast of South Africa 



Sabine P. Wintner 

 Geremy Cliff 



Natal Sharks Board 



Private Bag 2 



Umhianga Rocks 4320, South Africa 



E-mail address (for S P Wintner) wintner.S'sfiark co za 



Manuscript accepted 30 April 1998. 

 Fish. Bull. 153-169(1999). 



The white shark, Carcharodon 

 carcharias, is found worldwide in 

 cold and temperate coastal and 

 shelf waters (Compagno, 1984). As 

 a large, uncommon apex predator, 

 it has received considerable atten- 

 tion from scientists over the past 

 few years. Because of its great re- 

 sale value, compared with most 

 other sharks, catches of white 

 sharks have increased in various 

 parts of the world, mainly in Aus- 

 tralia and South Africa (Compagno, 

 1990, 1991). Claims of a declining 

 population size in South Australian 

 waters (Compagno, 1991; Bruce, 

 1992) influenced an initiative to 

 implement protective legislation for 

 this species in South Africa. In 1991 

 the South African government pro- 

 hibited the catching or killing of 

 white shark without a permit 

 (Compagno, 1991). This measure 

 was a preemptive protection and is 

 to be reviewed as results of more 

 research into the biology of this spe- 

 cies become available (Compagno, 

 1991 ). Protection has now also been 

 introduced in California, Florida, 

 and Tasmania (Fergusson et al., in 

 press), as well as in Queensland, 

 New South Wales, South Australia, 

 and Western Australia (Stevens') 



Legislation in South Africa has 

 prevented this species from being 

 targeted by commercial and recre- 

 ational anglers. White sharks con- 

 tinue to be caught on the east coast 

 in the nets of the Natal Sharks 



Board (NSB), which operates a 

 shark control program to protect 

 beach users against shark attack 

 (Cliff et al., 1988). Between 1984 

 and 1995 an annual average of 40 

 C. carcharias were caught in NSB 

 nets, and 159^ were released alive. 

 This activity has formed the basis 

 of a small-scale tagging program 

 that has provided the first esti- 

 mates of the size of the white shark 

 population (Cliff et al., 1996b). In- 

 formation about the distribution, 

 diet, movements, and catches of C 

 carcharias in South Africa is avail- 

 able from Bass et al. ( 1975) and Chff 

 etal. (1989, 1996a). 



Little is known about age and 

 growth of C carcharias, mainly be- 

 cause so few are caught at any one 

 locality, thus hampering collection 

 of vertebral samples for ageing pur- 

 poses. Knowledge of age at matu- 

 rity, maximum ages, and growth 

 rates is a prerequisite for age-based 

 methods of stock assessment, which 

 in turn can be used for the manage- 

 ment of this species. The only pre- 

 vious attempt at ageing the white 

 shark was that of Cailliet et al. 

 (1985) who had access to only 21 

 samples, mainly from California. 

 This study attempts to provide age 

 estimates for C. carcharias from 

 South Africa from vertebral growth 

 ring counts of 114 sharks. 



Stevens, J. D. 1997. CSIRO Marine Labo- 

 ratories. Tasmania, Australia. Personal 

 comm 



