Author: (Peron, 1807)
Field Marks:
A broad-headed, small-eyed, large seven-gilled shark with one dorsal fin and usually small, numerous black spots on body.
Diagnostic Features:
Head broad and rounded or bluntly pointed, with 7 pairs of gill slits on head; eyes small; mouth wide and arcuate; large lower comblike teeth high and short, with mesial serrations, a low cusp, and 5 or 6 distal cusplets in adults. Caudal peduncle short, distance from dorsal fin insertion to upper caudal origin about equal to length of dorsal base. Colour: body usually with numerous small black spots, but dorsal fin and upper caudal lobe without black tips.
Geographical Distribution:
Wideranging in mostly temperate seas. Western South Atlantic: From southern Brazil to northern Argentina. Eastern South Atlantic and Western Indian Ocean: From Namibia, southern Africa to India. Western Pacific: From southern Japan, the Koreas, China, also Australia (New South Wales, Victoria, Tasmania, South Australia), and New Zealand. Eastern Pacific: From British Columbia, Canada to southern California, USA, Gulf of California, Mexico, also from Peru to central Chile.
Habitat and Biology:
Marine and benthic, neritic, on the continental shelves; depth to at least 46 m, but often shallow water less than 1 m deep and at the surface.
A coastal shark, common in shallow bays and close to shore, often caught at the surfline, but with larger individuals ranging into deeper water offshore and deep channels in bays. Active and strong-swimming, often found cruising steadily and slowly near the bottom but sometimes at the surface; can dash at speed when attacking prey. Apparently coordinates its movements in bays with the tidal cycle, moving in with a tidal rise and out with its fall.
Ovoviviparous but with reproduction little known; litters large, up to 82 young. Gravid females apparently drop their young in shallow bays.
A powerful predator, rather indiscriminate in its feeding habits; may prefer other sharks (including spiny dogfish, houndsharks, and also hooked conspecifics which it readily attacks) and rays (eagle rays commonly taken), also bony fishes (Pacific salmon, sturgeon, herring, anchovies, and probably many others) and carrion (including porpoise, dolphin, rats, and even human flesh). Aggressive when provoked, and regarded as potentially dangerous to people in open waters. It has attacked divers in captivity, and may have been involved in a few shark attacks off California and South Africa; however, verified attacks by this species on people in open waters have not been recorded. It vigorously snaps and thrashes when captured by fishermen, and is often subdued by firearms or powerheads before being boated.
Size:
Maximum total length about 290 cm and possibly between 3 and 4 m; an old record at 4.6 m was based on Hexanchus griseus. Size at birth between 45 and 53 cm; males maturing between 150 and 180 cm and reaching at least 226 cm; females maturing between 192 and 208 cm and reaching at least 288 cm.
Interest to Fisheries:
The large size, local abundance and high-quality flesh of this shark makes it the subject of fisheries in several areas where it occurs. In California, USA and southern Australia it is fished by sport and commercial fishermen for human consumption, but it is also utilized in China for its skin, which produces leather of good quality, and its liver, which yields oil with high concentrations of Vitamin A. It is fished with rod and reel and longline gear, on the bottom. In California fishermen capture it from boats at moderate depths (down to at least 30 m), but on the Cape coast, South Africa, sports fishermen commonly hook it from shore.
Remarks:
I follow Bass, d'Aubrey and Kistnasamy (1975c) and Kemp (1978) in tentatively recognizing a single species of Notorynchus, N. cepedianus. The characters used by Fowler (1941) to separate N. pectorosus from N. cepedianus (presence of a medial tooth on the upper symphysis and serrations on the premedial or symphyseal edge of the lower comblike anterolateral teeth of the former, and absence of a medial tooth on the upper symphysis and serrations weak or absent in the latter) apparently are the result of individual variation within a single species (Kemp, 1978; also from series of Notorynchus specimens from San Francisco Bay, California, USA, examined by the writer).
The identity of the species of Notorynchus from Indian waters needs to be confirmed. This is often accorded a separate species, N. indicus (Agassiz, 1835), but this is not separable from N. cepedianus using available data on the species. I tentatively include it in N. cepedianus pending new information clarifying its status. A visit to India by the writer in 1982 revealed no extant material of Notorynchus in collections, but uncovered the first record of Heptranchias perlo from India (Compagno and Talwar, 1982, in press). It is possible that records of Notorynchus from India are erroneous (P.K. Talwar, pers.comm.).
Type material:
Holotype: Unknown. Type Locality: Adventure Bay, Tasmania.