Description:

A large hammerhead light grey-brown dorsally (mature females often a much darker olive-grey shade) fading to cream or white ventrally. The anterior edge of the cephalophoil 
(head) has a distinctive central notch flanked either side by two further indentations giving the head its characteristic scalloped appearance. The body has a laterally 
flattened fusiform (spindle) shape. The first dorsal fin is high and moderately falcate. The pectoral fins are ventrally black-tipped and there is a terminal dark blotch 
on the lower caudal lobe. Black tips fading to dusky or just dark edged in adults. No interdorsal ridge. Mid-sized gills. Large round eyes placed in middle of lateral 
cephalophoil processes. Mouth quite acutely arched.

Maturity: male 140-165 TL, female approx. 210 cm TL. Max Length: males 370cm TL, females 420cm TL.

Species of island and continental shelves and adjacent deep water, from the surface to 1000m depth (depth range usually 0-25m, but down to 1000m or more). Juveniles 
mainly occur in shallow inshore areas, sub-adults in deeper water. Horizontal migration is observed from inshore bays to a pelagic habitat as the sharks grow. 
Vivaparous 13-31 pups per litter after an 11-12 month gestation. Eat rays, teleosts and invertebrates. This species segregates by sex, with females migrating offshore 
earlier and at smaller sizes than males.

This species is not protected or subject to fishery regulations. It is however illegal to fish for sharks with nets (Fisheries Act, Reg 16.c). It is caught in the long line, 
hand line and gill net fishery. Of the three species of hammerhead recorded in Seychelles waters S. lewini is by far the most commonly caught in the artisanal shark fishery.
 

Ebert, D.A. et al (2013). Sharks of the World – A fully illustrated guide. Wild Nature press ISBN 978-0-9573946-0-5
Fisheries Act 2014. Prohibition of net fishing of sharks, Reg. 16c of 1st August 1998. (Carried over from the 1986 Fisheries Act as per Fisheries Act 2014 para 79: 
Savings and Transitional provisions).
Froese, R. and D. Pauly. Eds. (2018). FishBase. www.fishbase.org. https://www.fishbase.de/summary/Sphyrna-lewini (21/08/18).
Florida Museum (2018). Sphyrna lewini. https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/sphyrna-lewini/  (21/08/18).
Nevill, J.E.G. et al (2015). An identification guide for the sharks of the Seychelles Artisanal Fishery.
Rigby, C.L. et al (2019). Sphyrna lewini. The IUCN Red List 2019: e.T39385A2918526. (27/09/21).

Nevill, J.E.G. (2019). Sphyrna lewini, Scalloped hammerhead. Seychelles Seatizens. www.seatizens.sc. https://seatizens.sc/species/sphyrna-lewini-griffith-smith-1834/ (Updated 27/09/21).