Author: (Lowe, 1839)
Field Marks:
Long dorsal caudal lobe nearly as long as rest of shark, notched or helmeted contour of head, huge eyes extending onto dorsal surface of head, falcate but rather broad-tipped pectoral fins.
Diagnostic Festures:
Eyes very large, with orbits expanded onto dorsal surface of head; dorsal profile of head indented and forehead weakly convex in lateral view; space between dorsal edges of eyes nearly flat; snout moderately long, bulbous; a deep horizontal groove present on each side of head above gills; labial furrows absent; teeth moderately large, less than 25 rows in either jaw. Pectoral fins falcate with broad apices; terminal lobe of caudal fin moderately large. Light colour of abdomen not extending over pectoral fin bases.
Geographical Distribution:
Oceanic and coastal, virtually circumtropical. Western Atlantic: New York to Florida (USA), Bahamas, Cuba, Venezuela, and southern Brazil. Eastern Atlantic: Portugal, Madeira, Senegal, Guinea to Sierra Leone, Angola; also Mediterranean Sea. Western Indian Ocean: South Africa, Madagascar, Arabian Sea. Western Pacific: Southern Japan, Taiwan (Province of China), New Caledonia, Australia (northwestern coast), New Zealand. Central Pacific: North and south of Hawaiian Islands. Eastern Pacific: Southern California, Gulf of California and west of Galapagos Islands.
Habitat and Biology:
Found in coastal waters over the continental shelves, sometimes close inshore in shallow waters, and on the high seas far from land; sometimes caught near the bottom in deep water. Depths of occurrence range from the surface to at least 500 m.
An epipelagic, neritic, and epibenthic shark, apparently strong-swimming. Ovoviviparous, with uterine cannibalism, number of young usually 2 per litter, but sometimes up to 4. Feeds on pelagic (lancetfishes, clupeoids, scombroids, and small billfishes) and bottom fishes (hakes); also squids. Apparently stuns its prey with its long caudal fin, as individuals are often tail-hooked on longlines. Apparently harmless to people.
Size:
Maximum total length about 461 cm, smallest adult male reported 270 cm and largest about 400 cm, smallest adult female about 355 cm and largest over 430 cm; size at birth between 64 to 106 cm, full term fetuses have been collected at 105 or 106 cm.
Interest to Fisheries:
Generally 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. The bigeye thresher is a very important component of the Cuban longline fishery, and has recently been taken in considerable numbers by longliners off the northeastern USA. The species is also taken in fixed bottom and pelagic gillnets, in trawls, and with sportsfishing gear (rod and reel). Its meat is utilized fresh, smoked and dried salted for human consumption, its liver oil is processed for vitamins, its skin for leather, and fins for shark-fin soup.
Remarks:
See Gruber and Compagno (1982) for a discussion of the synonymy of A. profundus with this species, and for a general review of the biology of A. superciliosus.
Type material:
Holotype: Unknown. Type Locality: Madeira. eastern Atlantic.