Author: (Bonnaterre, 1788)
Long curving dorsal caudal lobe about as long as rest of shark, relatively small eyes, falcate, pointed pectoral fins, white colour of abdomen extending over pectoral fin bases.
Eyes moderately large at all sizes, orbits not expanded onto dorsal surface of head; dorsal profile of head convex and forehead strongly convex in lateral view; space between dorsal edges of eyes broadly convex; snout relatively short, conical and pointed; no grooves on head above gills; labial furrows present; teeth small, over 29 rows in either jaw. Pectoral fins falcate and narrow-tipped; terminal lobe of caudal fin moderately large. White colour of abdomen extending over pectoral fin bases as a conspicuous patch.
Oceanic and coastal, virtually circumglobal in warm seas. Western Atlantic: Newfoundland to Cuba, Gulf of Mexico, Venezuela, Brazil to Argentina. Eastern Atlantic: Norway and British Isles to Mediterranean, Morocco, Ghana and Ivory Coast; also Cape Province, South Africa. Indo-West Pacific: South Africa, Tanzania, Somalia, Maldives, Chagos Archipelago, Gulf of Aden, Pakistan, India, Sri Lanka, Sumatra, Japan, Republic of Korea, China, Australia (Queensland, New South Wales, Victoria, Tasmania, South Australia), New Zealand, New Caledonia. Central Pacific: Society Islands, Fanning Islands, Hawaiian Islands. Eastern Pacific: British Columbia to central Baja California, Panama, Chile.
Habitat and Biology:
Coastal over the continental and insular shelves and epipelagic far from land in temperate to tropical waters; young often close inshore and in shallow bays. Depth range from the surface to 366 m.
An active, strong-swimming shark, sometimes leaping out of the water. Populations in the northwestern Indian Ocean show spatial and depth segregation by sex. Ovoviviparous and apparently a uterine cannibal, number of young 2 to 4 in a litter (usually 2). Feeds mostly on small schooling fishes, including mackerels, bluefishes, clupeids, needlefishes, lancetfishes and lanternfishes; also squids, octopuses and pelagic crustaceans, and rarely seabirds. Herds and stuns its prey with its long, whiplike caudal fin, and is often caught on longlines by being tailhooked. A few attacks on boats are doubtfully attributed to this species but it is otherwise apparently harmless to people, though the size of adults of this species should invite respect. There is an unconfirmed anecdotal account of a fisherman on the western North Atlantic coast of the USA that was decapitated by a tailstroke from a big adult thresher (Mundus and Wisner, 1971). Small specimens have been seen underwater by divers, at the surface or close to the bottom, and have circled them at the limit of visibility without acting aggressively.
Maximum total length 549 cm and possibly to 609 cm, adult males 319 to at least 420 cm, adult females 376 to 549 cm; size at birth 114 to 150 cm.
Interest to Fisheries:
Caught in the oceanic longline fisheries operated by the USSR and Japan; especially important areas for these fisheries are the northwestern Indian Ocean and the central Pacific, but the species is caught elsewhere on longlines. Also fished with anchored bottom and surface gillnets, floating gillnets and sportsfishing gear (rod and reel); the species has recently become the object of an important pelagic gillnet fishery off southern California. The meat is highly prized fresh for human consumption but is also eaten smoked and dried salted; the fins are valuable for shark-fin soup; the hide is usable for leather and the liver oil can be processed for vitamins.
Holotype: Unknown. Type Locality: Mediterranean Sea.