Description:

Large hammerhead, dark olive grey to dark grey dorsally and white underside. Some individuals have dusky or black-edged pectoral fins. The cephalophoil has a broad anterior 
margin without central notch. The mouth is acutely arched.

First dorsal fin is moderately high with rounded apex and falcate form; originating over the pectoral fin insertions. The back is smooth to the touch lacks an interdorsal 
ridge. Second dorsal and pelvic fins are short. Pectoral fins are of medium length with slightly falcate posterior margins.

Size:

Maturity: 210-240cm TL. Max Length: 400-500cm TL.

Habitat and Ecology:

Coastal and pelagic it occurs over continental and insular plains as well as far offshore (0-200m depth, usually 0-20m). In shallower waters it is often bottom associated. 
Feeds on a variety of teleosts as well as small sharks, rays, crustaceans and cephalopods. Viviparous, 20-50 pups per litter, 10-11 month gestation period. No evidence to 
date that they breed in Seychelles waters.

Fishery Status:

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 hand line 
and long line fisheries. It is a rare component of the artisanal catch. 

Notes:

No completely intact specimens yet encountered, hence the photo of a dressed carcass.

References:

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).
Florida Museum (2018). Sphyrna zygaena. https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/sphyrna-zygaena/ (23/08/18).
Froese, R. and D. Pauly. Eds. (2018). FishBase. http://www.fishbase.org/summary/917 (22/08/18).
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 zygaena. The IUCN Red List 2019: e.T39388A2921825. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T39388A2921825.en. (27/09/21).
SharkReferences.com (2018). Sphyrna zygaena https://shark-references.com/species/view/Sphyrna-zygaena (23/08/18).

Citation:

Nevill, J.E.G. (2019). Sphyrna zygaena, Smooth hammerhead. Seychelles Seatizens. www.seatizens.sc. https://seatizens.sc/species/sphyrna-zygaena-linnaeus-1758/  (Updated 28/09/21).