[Diagnosis] [Size] [Biology] [Interaction with Man]

Diagnosis
Diagnosis A large, heavy-bodied shark of fusiform shape, with crescentic tail and conical snout. First dorsal fin broadly triangular, with origin above or slightly posterior to the axil of the pectoral fins. Second dorsal fin minute, lying anterior to the equally-small anal fin; strong caudal keels. Teeth are essentially broad and triangular, with serrated margins, distinguishing this species from the other lamnids. Newborns (neonates) have narrower teeth, with basal cusps on the lower jaw dentition. Colour slate-grey or olive-brown above, often with a bronzy sheen on the flanks; strong, variable and blotchy line of demarcation between dark dorsal surfaces and white ventral surfaces; underside of pectorals tipped with black; a black, oval blotch often present in the axil of the pectorals although this is sometimes absent on Mediterranean specimens. Newborn white sharks are often locally misidentified as Isurus oxyrinchus or Lamna nasus.

Size
Probably to 714cm (females); ca. 530 cm (males) based on recent regional specimens; commonly from 350 to 540cm TL in Mediterranean; also juveniles between 120 to 250 cm. Size at birth 120 to 150 cm.

Biology
An active, voracious predator of coastal, insular and offshore waters; occasionally in bays and harbours; also penetrating narrow straits such as the Dardenelles; found from the surfline to at least 50 miles offshore (Sicilian Channel) and at depths from the surface to ca. 200 metres in the region. Often encountered over offshore banks (e.g., Hecate, Talbot and Aventure, Sicilian Channel) and in the vicinity of fisheries for bluefin tuna (Favignana [Sicily] & Malta) or swordfish (Calabria & Messina). The white shark preys regionally upon bottlenose, striped and common dolphins, large bony fishes (especially tunas, bonito and swordfish), other sharks (blue sharks and shortfin makos); dasyatid rays and sea-turtles. It also scavenges readily from coastal and offshore fisheries and takes dead whales, dolphins and domestic mammals as carrion. Capture data and observations of free-swimming examples strongly infer a propensity towards aggregation at selected sites, mainly insular, on an annual basis and seemingly for feeding, courtship or both; typically such locales are sited on the migratory routes of mature bluefin tuna and are most seasonally pronounced during the spring and early summer months. Although long considered a solitary hunter, more recent work (particularly in South Africa) has shown the white shark to exhibit complex social behaviours and also non-predatory behaviours towards other marine organisms (and humans). Based on neonatal captures and the localised dual presence of mature males and females, white sharks apparently reproduce in the region, with the Western Sicilian Channel forming the focus for this activity. A single confirmed pregnant female has been taken in Mediterranean waters, off Cape Bon, Tunisia (1992) and contained two foetuses (the remaining litter possibly aborted upon capture). The species is aplacentally viviparous and embryos are nourished by ingesting unfertilised eggs (oophagy); litters of 6 to 11 young and parurition probably in the spring and summer over warm-temperate shelf waters. Males mature at ca. 360cm TL; females at 450-500cm.

Interaction with Man
Limited. Incidentally caught annually but infrequently in fisheries for pelagic teleosts, (bluefin tuna and swordfish), by fixed-traps (Tonnara), harpoon, gill-nets and set-lines; smaller specimens by longlines at the surface and on the bottom; juveniles taken by bottom trawls down to 200m in the Sicilian Channel. Sometimes directly hunted (usually with little success), mainly off Italy in the wake of fatal or injurious shark attacks; also sought as a gamefish on a short-term basis following repeated sightings of assumedly single individuals. Infrequently present on fishmarkets; usually juvenile specimens; flesh utilised for human consumption; jaws and teeth sold as curios. Implicated or confirmed in the majority of attacks on swimmers, divers and boats within the region and should be treated with great caution, but recent subsurface encounters between divers and large white sharks at Sicilian Channel sites (e.g., at Pantelleria, Malta, S.W. Marretimo) demonstrate that these sharks will more readily investigate divers and depart without any mode of physical contact. Their welfare in Mediterranean waters is of increasing concern, not least as traditional prey-sources (such as tuna) are grossly over-exploited and historical coastal habitats increasingly degraded (North Adriatic Sea).