Scalloped hammerhead

IDENTIFYING FEATURES

Its head is shaped with the eyes on the end of a “hammer” to give a wide range of vision, an advantage when chasing after fast-moving fish.

Scientific name: Sphyrna lewini
Common names: Scalloped hammerhead shark
Family: Sphyrnidae 
Size: Males can grow to 340cm and females to 346cm

DISTRIBUTION

The scalloped hammerhead has a worldwide distribution in coastal, warm temperate and tropical seas.

HABITAT

This is a coastal and semi-oceanic pelagic shark, found over continental shelves and in deep water near to them. The pups of this species tend to stay in coastal zones, near the bottom, occurring in high concentrations in estuaries and bays during summer.

DIET

Adults feed on fish, small sharks, squid and stingrays and juveniles feed on reef fish and crustaceans.

REPRODUCTION

Hammerhead sharks are known to congregate in large shoals when spawning takes place. The species is viviparous. The gestation period is between 9 and 10 months, with birth in spring and summer. The number of pups ranges from 13 to 31. Predation on pups and juveniles is high, mainly by other sharks and even by adults of the same species.

Length at maturity: males 180 cm, females 250 cm
Age at maturity: males 10 years, females 15 years
Maximum age: 30 years

DID YOU KNOW?

The unusual head shape is thought to perform a number of functions:

  • It can serve as a bow plane to increase lift and maneuverability.
  • Smell and visual perception may be enhanced by spreading the sense organs over a wider area.
  • They are known to use their head to hold stingrays down on the sea bed whilst biting at them.

REGULATIONS

Daily recreational bag limit: one
SASSI: Red list

CONSERVATION

The scalloped hammerhead shark is caught by trawls, purse-seines, gillnets, longlines and inshore artisanal fisheries. The latter catch large numbers of pups and juveniles in some regions. The species’ aggregating habit makes them vulnerable to capture in large schools. Their fins are being increasingly targeted in some areas in response to increasing demand for shark fins.

Scalloped hammerhead shark