Featured Elasmobranch-Scoophead Shark

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Featured Elasmobranch-Scoophead Shark

December 2011

Scoophead Shark

Sphyrna media (Springer 1940)

Family Sphyrnidae, Hammerhead sharks

Identification: This hammerhead shark has a moderately broad but short mallet-shaped side extensions of the head (the width of the cephalofoil is 22-33% of TL).  The front margin of the head is broadly arched, and the snout is moderately long (length before mouth is usually roughly 1/3 of head width).  The mouth is broadly arched, and front teeth are blade-like and smooth while the lower teeth are straight.  The first dorsal fin is moderately large and erect, with a rear margin that is noticeably concave.  The origin of the second dorsal fin is above the middle of the anal fin.  The tail fin is strongly asymmetrical, and notched under the tip of top lobe.  This shark has a grey-brown coloration on the back and sides, while lighter on ventral surfaces.

 

 

Size: Scoophead sharks reach a maximum of 150 cm total length.  Females mature at 100 cm TL, and males at 90 cm TL.

 

Distribution: They are found in the eastern Pacific from the Gulf of California to Peru, and the western Atlantic from Panama to Brazil.

 

Habitat: Little is known of the habitat of this shark. It is known that they can be found over soft bottom, shallow, inshore areas. They are demersal, and occur in areas of the continental shelf no deeper than 200m.

Biology: The diet of the scoophead shark consists of benthic and pelagic crustaceans, benthic gastropods and bivalves, cephalopods, echinoderms, and some bony fishes. They have a placental viviparous reproductive pattern, and pups are 30-35 cm at birth. The size at maturity is 100 cm TL and 90 cm TL for females and males respectively. The maximum size is estimated at 150cm TL. However, litter size, gestation time, average reproductive age, age at maturity, longevity, reproductive periodicity, average annual fecundity, annual rate of population increase, and natural mortality rate are unknown.

 

 

 

 

 

 

General Interest: These sharks are common as bycatch in the mackerel gillnet fishery in Trinidad.  It can be sold as fresh for human consumption, or utilized for fishmeal.  It is presumably also taken with bottom longlines, gillnets, and hook and line throughout its coastal range, but no information is available for the extent of capture and fishing practices.  Its current IUCN Red List classification is listed as Data Deficient.

Written by: Kelley Andrews
Pacific Shark Research Center
Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039

kandrews@mlml.calstate.edu