Great Hammerhead shark (Sphyrna mokarran)
Great Hammerhead Shark
Did You Know?
· Great hammerhead sharks are the largest of the hammerheads and can reach lengths of over 20 feet and weigh up to 1,280 pounds!
|Weight:||over 500 pounds (230 kg)|
|Length:||about 10-13 feet (3-4 m)|
|Appearance:||expanded head, in the shape of a hammer; serrated teeth; tall and curved first dorsal fin, relatively large second dorsal fin and anal fin with deep notches in the rear margins; fusiform body with dark brown to light grey or olive shades on dorsal side and white underside|
|Lifespan:||about 40 years; maturity is reached at 6-8 years|
|Diet:||fishes, cephalopods, crustaceans, with a preference for stingrays|
|Behavior:||"viviparous," mothers give birth to live young; gestation is thought to last 10-11 months with litter sizes anywhere from 6 to 55 pups, they typically give birth every 2 years|
Great hammerhead sharks are the largest of the hammerhead species. They can reach lengths of over 20 feet (6.1 m), however most are usually less than 13 feet (4 m). The eight or so species of hammerhead sharks are characterized by the flat, extended head or "cephalofoil." The cephalofoil of a great hammerhead shark is characterized by a nearly straight front margin, with a median indentation in the center of the head in adults.
The great hammerhead shark can be found in coastal warm temperate and tropical waters. They are usually observed in coastal waters and over continental shelves, but may also be found in adjacent deep waters and in coral reefs and lagoons.
Great hammerhead sharks are highly migratory and can be found worldwide in appropriate habitat. Along the U.S. Atlantic coast, the great hammerhead shark may be observed in waters off Massachusetts (although the species is rare north of North Carolina) south to Florida, and may also be found in the Gulf of Mexico.
Declines in great hammerhead populations have been observed in some areas of its range. Because of the similarity in appearances, catches of great hammerheads tend to be grouped with those of other hammerhead shark species (mainly smooth and scalloped), confounding species-specific population trend analyses. We are conducting an Endangered Species Act status review of this species and will update this section as more information becomes available.
Shark fin trade
This species is highly desired for the shark fin trade because of its larger fin size and high fin ray count. They are caught in a variety of fisheries including:
- artisanal and small-scale commercial fisheries
- bottom longline fisheries
- offshore pelagic longline, gillnet, and similar fisheries
They are valuable in the international fin trade and are often used to make shark fin soup. Compilation of market prices from auction records indicates an average, wholesale, unprocessed hammerhead fin market value of US $45-100/lb.
Due to their similarity in appearance to the scalloped hammerhead shark, both the great and smooth hammerhead sharks have been added to CITES Appendix II in an effort to better regulate the international trade of all three species to ensure their sustainability.
In March 2013, at the CITES Conference of the Parties meeting in Bangkok, member nations, referred to as "Parties," voted in support of listing three species of hammerhead sharks (scalloped, smooth, and great) in CITES Appendix II—an action that means increased protection, but still allows legal and sustainable trade. This CITES listing will go into effect on September 14, 2014. At that time, export of their fins will require permits that ensure the products were legally acquired and that the Scientific Authority of the State of export has advised that such export will not be detrimental to the survival of that species.
On December 21, 2012, we received a petition from WildEarth Guardians to list the great hammerhead shark (Sphyrna mokarran) as threatened or endangered under the ESA throughout its entire range, or, as an alternative, to delineate the species into distinct population segments (DPSs). On March 19, 2013, we received a petition from Natural Resources Defense Council to list the northwest Atlantic population of great hammerhead sharks as a threatened DPS, or, as an alternative, to list the great hammerhead shark as threatened throughout its range. On April 26, 2013, we published a notice that listing of great hammerhead sharks may be warranted, and we commenced a status review of the species. In June 2014, we completed the status review and determined that the species does not warrant listing at this time.
(All documents are in PDF format.)
|"Not Warranted" for listing 12-Month Finding||79 FR 33509||06/2014|
Positive 90-day finding on Petitions To List the Great Hammerhead Shark Under the ESA; Request for Information and Initiation of Status Review
|78 FR 24701||04/26/2013|
|Petition to List the Northwest Atlantic or range-wide population as Threatened and Designate Critical Habitat||03/19/2013|
|Petition to List as Threatened or Endangered and Designate Critical Habitat||12/21/2012|
- CITES conference takes decisive action to halt decline sharks, other species
- NOAA's role in CITES
- IUCN Red List species information
Updated: July 10, 2014