Sphyrna Lewini
Family
Sphyrnidae (Hammerhead, bonnethead, or scoophead sharks)
Order
Carcharhiniformes (ground sharks)
Class
Elasmobranchii (sharks and rays)
Maximum Size
430 cm TL (male/unsexed); max. published weight: 152.4 kg; max. reported age: 35 years
Environment
reef-associated; oceanodromous; brackish; marine ; depth range 0 - 275 m
Climate
Subtropical; 46°N - 36°S, 180°W - 180°E
Importance
fisheries: commercial; gamefish: yes
Resiliance
Low, minimum population doubling time 4.5 - 14 years (rm=0.028; K=0.1; tm=4-15; tmax=35; Fec=13-23)
Distribution
Circumglobal in coastal warm temperate and tropical seas. Western Atlantic: New Jersey, USA to Brazil, including the Gulf of Mexico and Caribbean. Eastern Atlantic: Mediterranean to Namibia
Diagnosis
Dorsal spines (total): 0-0; Anal spines: 0-0. A large hammerhead with a notch at the center of head; 1st dorsal fin moderately high, 2nd dorsal and pelvic fins low. Front margin of head broadly arched with prominent median notch. Side wings of head narrow, rear margins swept backward. Uniform grey, grayish brown, or olivaceous above, shading to white below; pectoral fins tipped with grey or black ventrally. .
Biology
A coastal-pelagic, semi-oceanic shark occurring over continental and insular shelves and adjacent deep water, often approaching close inshore and entering enclosed bays and estuaries. Found in inshore and offshore waters to about 275 m depth. Huge schools of small migrating individuals move pole ward in the summer in certain areas. Permanent resident populations also exist. Adults solitary, in pairs, or schools; young in large schools. Viviparous. Produces 15-31, of 43-55 cm young in a litter. Feeds mainly on teleost fishes and cephalopods, also lobsters, shrimps, crabs, including other sharks and rays. Considered potentially dangerous to people but often not aggressive when approached by divers. Readily available to inshore artisanal and small commercial fisheries as well as to offshore operations. Sold fresh, dried-salted, smoked and frozen; also sought for its fins and hides. Oil used for vitamins and carcasses for fishmeal.
