ECOLOGY: INDIAN OCEAN SHARKS 



547 



30° 



50" 



10°- 



V 



-10° 



INDIAN 

 OCEAN 



Wallets 

 Shoal 



30 



30° 



50° 



Figure 1 The southwest Indian Ocean with an indication of the major current systems. 

 The 100-fathom depth contour is shown as a dotted line from Beira southwards along the 

 African coast. (After Figure 1 of Bass et al. 1973.) 



Mozambique Current is thus reduced in strength. In addition, the latter may 

 form a discrete circulation in the Mozambique channel at this season, so that 

 the Agulhas Current is fed by only that part of the Equatorial Current that 

 runs along the east coast of Madagascar. The Agulhas Current thus penetrates 

 furthest along the east coast during summer, when warm Agulhas water may 

 extend as far as the Cape Peninsula. In winter the relatively cool south coast 

 waters may extend as far north as Natal in the form of an inshore counter- 

 current. 



The distribution of pelagic animals along the east coast thus depends on 

 the season, while that of sedentary animals is limited by the extremes of 

 temperature to which they may be subjected at different times. Seasonal 

 changes of inshore surface temperatures at four localities on the southern 

 African coast are shown in Table 1. 



