FISHERY BULLETIN: VOL. 85, NO. 2 



£ 



o 



^^ 



X 



I- 

 o 



z 



LU 



< 



I- 



o 



I- 



450 

 400 

 350 



300 

 250 

 200 

 150 

 100 



Galeocerdo cuvieri 



? c? 9 



O ^ ir Gulf of Mexico 



O • Atlantic coast 



•• 



U« o , 



• o •* 



o 

 o • 



■sir • • 

 * T 



von Bertalanffy parameters 



1 



g 



Gulf 

 K =.184- 



L„=388 

 t» = -1.13 



Atlantic 

 .107 



440 



-2.35 



Combined 

 !l58 



388 



-1.73 



Winter marks 



5 



J , i_ 



9 11 13 15 



J I I I I r I L 



7 9 11 



AGE (yr) 



13 



I 



17 



Figure 4.— Length at age for Galeocerdo cuvieri from the Gulf of Mexico and the Atlantic coast of Virginia. In- 

 dividuals are plotted by their estimated actual ages (time elapsed since formation of the last winter mark). Birthdays 

 set at 1 June. 



at recapture, 7 April 1984, was estimated to be 320 

 cm from the weight/length relationship. The tiger 

 shark grew 90 cm in 5.4 years. By using the age/ 

 length relationship estimated by the growth curve 

 (Fig. 4), the shark would have been 3.4 years of age 

 when tagged and 8.8 years of age at recapture. 



Even with the relatively rapid growth rate ex- 

 hibited by this species, a length-frequency analysis 

 for both samples (Fig. 5) did not distinguish age 

 classes. The size distribution did indicate that young 

 juvenile tiger sharks occur only rarely in the Virginia 

 region. 



Males matured at approximately 310 cm, females 

 at 315-320 cm, and the differences in growth rates 

 between the two samples meant that they reached 

 maturity at different ages. For the Gulf of Mexico, 

 the smallest mature males (310, 311 cm) were 8.0 

 and 7.8 years old. The largest male aged (340 cm) 



was only 8.8 years old. Back calculations indicated 

 that this individual grew relatively rapidly compared 

 with smaller individuals in the sample, and the only 

 larger male collected (363 cm) was not aged. The 

 smallest mature female (325 cm) was 8.8 years old, 

 the largest (355 cm) was 11.2 years old. For the 

 Atlantic sample, two immature males (310, 311 cm) 

 were not aged, but a 312 cm mature male was 10.1 

 years old. The largest male (381 cm) was 15.1 years 

 old. The largest immature female (307 cm) was 8.1 

 years of age, the smallest mature females (318, 319 

 cm) were 9.0 and 11.1 years of age, and the largest 

 female (381 cm) was 16.1 years old. 



The rapid linear growth early in life did not cor- 

 respond to a great increase in the weight of the in- 

 dividuals (Fig. 6). Growth from the third through 

 the seventh winter decreased from 30 to 20 cm/year, 

 and weights increased during this period. As the 



274 



