GREAT WHITE SHARK

The white shark is primarily a fish eater, taking all manner of bony fish as prey, from sedentary bottom-living rockfish, lingcod and flatfish to fast open-ocean species such as broadbill swordfish and bluefin tuna.

A broad range of elasmobranchs - sharks and batoids - are eaten by white sharks, as are marine turtles, cephalopods (e.g., squid), molluscs, crustaceans (crabs) and occasionally seabirds.

The role of the white shark as a primary predator upon marine mammals, and especially seals and sealions (pinnipeds), has dominated much contemporary study and commentary on this species but the importance of these prey may be grossly overstated from a more global standpoint, due in part to the bias in contemporary study towards those areas where sharks and pinnipeds occur together.

White sharks (and especially larger individuals) are also active hunters of small cetaceans including dolphins and porpoises, particularly so (but not exclusively) in regions where pinnipeds are scarce or absent.

These opportunistic sharks will readily congregate to scavenge upon the carcasses of great whales and have been known to ingest basking shark flesh on a number of occasions, albeit apparently only through scavenging. 

Predatory Biology

The white shark is a formidible macropredator, with its primary prey marine vertebrates and its most important prey bony fishes, cartilaginous fishes, and marine mammals. Smaller sharks are primarily piscivorous, but with growth the maximum prey size becomes larger and larger juveniles and adults feed on a wide variety of small to large bony fishes, elasmobranchs, cetaceans, and pinnipeds as their principal prey, with other marine vertebrates and invertebrates also taken. Fish prey recorded from across the size-range of this species includes a number of elasmobranchs, such as juvenile dusky sharks, sandbar sharks, tope, spiny dogfish, smoothhounds and other houndsharks, bronze whalers, milk sharks, and blue sharks, shortfin makos, sandtigers, scalloped hammerheads, whiptailed stingrays (Dasyatidae), batrays, eagle rays, guitarfish (Rhinobatidae), wedgefishes (Rhynchobatidae), and elephantfish (Callorhynchidae). Bony fish taken include bluefin tuna, Atlantic bonito, albacore, bullet tuna and other scombrids such as frigate mackerel; hake, bluefish, swordfish, sardines and other herring-like fishes, sturgeons, sea catfish, cabezon, lingcod, rockfish, sea breams, croakers, jacks (Carangidae), barracuda, striped bass, Pacific salmon, halibut and flounders, and even ocean sunfish. Marine reptiles are sporadically ingested, and within Mediterranean waters white sharks have been caught with the remains of Loggerhead Caretta caretta and green turtles Chelonia mydas in their stomachs (Fergusson et al., in press). Cephalopods (such as squid and cuttlefish), gastropods and crustaceans are less important prey but benthic crabs may be ingested in suprising numbers by large sharks, which don't necessarily spurn small prey.

The role of Carcharodon as a primary predator upon marine mammals, particularly pinnipeds, is oft-cited but sometimes overemphasised versus the fish components in its diet. It is sometimes stated that larger sharks switch to pinnipeds as prey and are narrowly dependent on them, but this is apparently erroneous. In areas where pinnipeds are abundant and sympatric with white sharks, such as along the coasts of California, the Cape Province of South Africa,islands off South Australia, and the Otago region of New Zealand, these sharks will lurk off haul-outs and prey upon a variety of species including northern elephant seals Mirounga angustirostris, fur seals Arctocephalus spp., harbour seals Phoca vitulina, grey seals Halichoerus grypus, and sea lions including California sea lions Zalophus californianus and Australian sea lions Neophoca cinerea. The dynamics of such predator-prey relationships have been the focus for recent Californian studies, primarily at the Farallon Islands (Ainley et al., 1981; 1985; Klimley et al., 1992 and 1996) and at Ano Nuevo Island, a low, sandy feature north of Santa Cruz (Le Boeuf et al., 1982; S. van Sommerman, pers.comm.). Similar field studies have been pursued off Cape Province, South Africa, by the Shark Research Center (SRC) of the South African Museum.

Cetaceans - and especially dolphins - are a common prey-item in the Mediterranean and elsewhere, including within regions where pinnipeds also occur and are preyed upon (e.g., Spencer Gulf of South Australia; Bruce, 1992;Western Cape, South Africa). Taken free-swimming and opportunistically scavenged from the nets of fishermen and beach meshing programmes, dolphins are known to fall prey to great whites off South Australia (Bruce, 1992), Western Australia (Cockeron et al.) South Africa (Cliff et al., 1989; Compagno, 1991) and in the Mediterranean (Postel, 1958; Fergusson, 1994). In the latter area, bottlenose dolphins Tursiops truncatus are the most frequent prey species. Other odontocetes (toothed whales) taken by these sharks include common dolphins Delphinus delphis off Tunisia (Postel, 1958), harbour porpoises Phocoena phocoena in the Canadian Atlantic (Arnold, 1972), pygmy sperm whale Kogia breviceps and Dall's porpoise Phocoenoides dalli off California (Long, 1992; 1996); also dusky dolphins Lagenorhynchus obscurus and Indo-Pacific humpback dolphins Sousa plumbea within other regions. The carcasses of great whales are readily scavenged by white sharks in feeding aggregations off Long Island (e.g., Carey et al., 1982; Pratt et al., 1982), California (P. Pyle, pers. comm; R. Collier, pers. comm), South Africa and elsewhere. This interrelationship between white sharks and cetaceans is by no means a new one - scars attributable to these sharks have been found marking the fossilised skeletons of bottlenose dolphins (see Cigala Fulgosi, 1990, for a detailed example from Italy) and cetotheriid whales (Demere and Cerutti, 1982).

Interestingly, the white shark will often bite, but rarely ingest, two groups of prey. Firstly, seabirds - particularly jackass penguins Spheniscus demersus on islands off the South African coast - are commonly found to have suffered cursory injurious or mortal 'grab-release' , 'slash' (apparently with the tips of the lower and upper teeth), and 'bash' (with the upper teeth) bites from white sharks (Randall et al., 1988; M.A. Marks, pers. comm.) but are rarely ingested. Other avians including brown pelicans, cormorants, gannets and gulls suffer similar fate, albeit not always culminating in some disabling injury. Ian Fergusson witnessed an entire sequence at Dyer Island wherein a cormorant (Phalacrocorax sp.) was grab-released by a white shark, commencing with the surface-resting bird being taken suddenly by a leaping white shark and carried airborne in its mouth, before being taken subsurface for a few seconds. Much to his incredulity, the bird then re-surfaced and flew-off, showing no visible sign of mishap after the impromptu 'slam-dunk' (Fergusson, 1995). Birds are also 'bounced' (sharks come up underneath gulls and other seabirds sitting on the surface and send them tumbling with an upward flip of their heads), and are either grabbed or not. Sea otters (Enhydra lutris) are mortally injured by white sharks off central California, especially near Monterey and Carmel (Ames and Morejohn, 1980; Ames, 1996) but have yet to be found in white shark stomachs. Exactly why birds and sea-otters are almost exclusively rejected as prey is unclear, but perhaps this phenomena has some enigmatic bearing upon the reasons why most human victims of white shark attack are also released, usually after a very limited and non-energetic contact of a nature that is at odds with the unquestionable power of these fish and the massively traumatic and swiftly lethal nature of full-fledged feeding attacks on similar-sized pinnipeds and other marine vertebrates. However, even regular prey animals such as young of the year Cape fur seals may be lightly grabbed by white sharks and released with little injury (M.A. Marks, pers. comm.).

White sharks will scavenge from fishermens nets and longlines and will take all manner of hooked fish, including conspecifics, taken by rod-and-line. This propensity often results in their own accidental entrapment. In Mediterranean waters and elsewhere, it is because of this opportunistic behaviour that many white shark captures are made by means of the predators scavenging large fish and other sharks taken by longlines, or entrapped in gillnets, on setlines or other fishing modes. In addition, large specimens are sporadically taken by swordfish harpoons within the Straits of Messina, Sicily. Firm evidence of these sharks scavenging fishery discard is afforded by the discovery of a 2 metre bottlenose dolphin carcass in the stomach of a 535cm white shark taken at Favignana, Sicily, in May 1987. The dolphin remains, bitten cleanly in two at the abdomen, were relatively fresh but clearly scavenged - a tightly-knotted nylon rope was bound around the caudal peduncle, an unmistakable sign that the mammal had been entrapped by driftnet, drowned and then retrieved by fishermen. At the time, fearful of environmental lobbying over cetacean mortality in these fisheries, local operators would habitually sink dolphin carcasses by knotting rope around the tails and attaching a stone anchor (Giuseppe Notarbartolo di Sciara, pers. comm.). In all likelihood, this dolphin was ingested post-mortem by a white shark which severed the carcass's anchor-rope during feeding.