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Sphyrna mokarran (Ruppell, 1837)
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Sphyrna mokarran (Ruppell, 1837)
  • Photo. (c) 2019 John Nevill.
  • Photo. (c) 2019 John Nevill.
  • Photo. (c) 2019 John Nevill.
Genus: ,

Scientific Name: Sphyrna mokarran

English Name: Great hammerhead

Creole Name: Marto blan

French Name: Grand requin marteau

IUCN Red List Status: Critically Endangered (CR)



Information

Description:

A very large hammerhead. Grey-brown dorsally white ventrally. Shallow notch at the centre of an otherwise near straight cephalophoil in adults (gently curved in juveniles). 
This gives an overall somewhat rectangular appearance to the cephalophoil particularly when viewed from the ventral surface. Mid-sized gill slits. Medium sized eyes 
situated towards the front of the lateral cephalophoil processes. The first dorsal fin is very high and strongly falcate with a narrow rounded to pointed apex. The 
trailing edges of the pelvic fins are concave. Interestingly international accounts state that Great hammerhead fins are plain and unmarked. This is not the case in 
Seychelles where the pectoral (underside), pelvic, anal, lower caudal and second dorsal have distinct dark/black tips. These markings are retained by adults particularly 
on the pectoral and pelvic fins, with others fading somewhat to dusky. 


Size:

Maturity: Male approx. 235-270cm TL, Female 250-300cm TL. Max Length: > 600cm TL.


Habitat and Ecology:

Coastal to pelagic and oceanic distribution over continental shelves, island terraces, in passes and lagoons of coral atolls and on coral reefs, 1 -80m depth or more.

Viviparous 6 to 42 pups per litter after an approximately 11 month gestation. Mature at around 7-8 years old in Seychelles waters. Known to feed on rays, batoids, and 
large teleosts.


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 long line, hand line and gill net fisheries. S. mokarran is today scarce in Seychelles waters with adults only an occasional component of the artisanal shark fishery catch.


Notes:
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).
Froese, R. and D. Pauly. Eds. (2018). FishBase. https://www.fishbase.de/summary/Sphyrna-mokarran.html (21/08/18).
Florida Museum (2018). Sphyrna mokarran https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/sphyrna-mokarran/ (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 mokarran. The IUCN Red List 2019: e.T39386A2920499. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T39386A2920499.en. (27/09/21).


Citation:

Nevill, J.E.G. (2019). Sphyrna mokarran, Great hammerhead. Seychelles Seatizens. www.seatizens.sc. https://seatizens.sc/species/sphyrna-mokarran-ruppell-1837/ (Updated 27/09/21).


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