ECOLOGY: INDIAN OCEAN SHARKS 



563 



North 6 



>2.4m 



South 8-1 



= 2. 4m 



n 



n H n 



_□_ 



Figure 9 Seasonal distribution of 117 Carcharodon carcharias taken in the shark nets off 

 Natal, divided into two arbitrary regions north and south of Durban. (After the data given 

 in Figure 38 of Wallett 1973.) Also shown are the monthly surf temperatures as recorded 

 at Durban. (After Figure 12 of Bass et al. 1975c.) 



pronounced seasonal occurrence with a peak in September and October. 

 Larger sharks occur in lesser numbers throughout the year with a slight peak 

 from March to May. In the southern part of Natal C. carcharias is definitely 

 more abundant, the younger sharks being found throughout the year with 

 only a slight peak in September and October. The larger specimens again 

 occur throughout the year without any marked seasonality. 



Bearing in mind that water temperatures are lower in southern Natal 

 as compared to the northern area, it seems clear that young C. carcharias 

 have a warm temperate rather than a tropical or subtropical distribu- 

 tion. In Durban and northwards these juveniles are caught only during 

 the cooler parts of the year. To the south of Durban, however, water 

 temperatures are somewhat lower and these young sharks are caught 

 throughout the year. Although we have few definite records, small 

 C. carcharias appear to be fairly common in southern and southwestern 

 Cape waters. (Bass et al. 1975c) 



