THE DIET OF RISSOS DOLPHIN, GRAMPUS-GRISEUS (CUVIER, 1812), FROM THE EAST-COAST OF SOUTH-AFRICA

Examined the stomach contents of Risso's dolphins (Grampus griseus), s tranded along the east coast of South Africa over a 22 year period (19 69-1991). Prey consisted exclusively of cephalopods from which sevente en species mere identified. Index of relative importance values were u sed to identify the most important prey. The most dominant prey Loligo vulgaris reynaudii, a shallow water, semipelagic subspecies constitut ed 81 % by mass of the total prey and 48.1 % and 29.2 % by number and frequency of occurrence, respectively. Other important species, were L ucotenthis diadema, Argonauta nodosa, Octopus magnificus and Ancistroc heirus lesueuri. The diversity of prey species differed for males and females and also between dolphin size classes. These data suggest a pa rtitioning of food resources between sub-groups. The results of this s tudy indicate chat Risso's dolphins probably feed in the Agulhas curre nt and also in coastal waters where the continental al shelf is narrow .