Scalloped Hammerhead Shark (Sphyrna lewini)
Status | Taxonomy | Species Description | Habitat | Distribution |
Population Trends | Threats | Conservation Efforts | Regulatory Overview |
Key Documents | More Info
 Scalloped Hammerhead Shark (Sphyrna lewini) Photo: NOAA |
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Did You Know? · Comment on the proposed listing of 4 DPSs, through 06/04/2013 |
Status
ESA Proposed Endangered
--Eastern Atlantic "DPS"
--Eastern Pacific "DPS"
ESA Proposed Threatened
--Central and Southwest Atlantic "DPS"
--Indo-West Pacific "DPS"
CITES Appendix II - effective 09/14/2013
CITES Appendix III - included by Costa Rica
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Sphyrnidae
Genus: Sphyrna
Species: lewini
Species Description
Scalloped hammerhead sharks are moderately large sharks with a global distribution. The eight or so species of hammerhead sharks are characterized by the flat, extended head or "cephalofoil." The cephalofoil of a scalloped hammerhead shark is characterized by an indentation located centrally on the front margin of the broadly arched head. Two more indentations flank the main central indentation, giving this hammerhead a "scalloped" appearance.
They feed on crustaceans, teleosts, cephalopods and rays.
Habitat
The scalloped hammerhead shark is a coastal pelagic species that can also be found in ocean waters and occurs over continental and insular shelves and adjacent to deeper water. It has been observed close inshore and even entering estuarine habitats, as well as offshore to depths of 1000m. Adult aggregations are common at seamounts, especially near the Galapagos, Malpelo, Cocos and Revillagigedo Islands and within the Gulf of California, but otherwise adults can be solitary or occur in pairs.
Distribution
Scalloped hammerhead sharks are found worldwide residing in coastal warm temperate and tropical seas in the Atlantic, Pacific, and Indian Oceans between 46°N and 36°S to depths of 1000 meters.
DPS Boundaries are shown in the map below:
Population Trends
A recent stock assessment (Hayes et al. 2009) found that the northwestern Atlantic population has decreased from about 155,500 in 1981 to about 26,500 in 2005.
- targeted fisheries, shark fin trade
- bycatch
This species is highly desired for the shark fin trade because of its fin size and high fin ray count. They are caught in a variety of fisheries including artisanal and small-scale commercial fisheries, bottom longlines as well as offshore pelagic longlines, gillnets, etc. They are valuable in the international fin and are often used to make shark fin soup. Compilation of market prices from auction records indicates an average, wholesale, unprocessed fin market value of US $50-100/lb.
Conservation Efforts
In October 2012, a number of countries agreed to sponsor a proposal to add scalloped hammerhead shark to Appendix II of CITES to provide further protections from the high demand in international trade. The proposal will be considered for adoption at the next CITES meeting in March 2013.
The United States offered a similar proposal (co-sponsored by Palau) at the last CITES meeting in March 2010. The proposal garnered a simple majority but failed to acquire the two-thirds majority needed for adoption.
Regulatory Overview
On August 14, 2011, we received a petition from WildEarth Guardians and Friends of Animals to list the scalloped hammerhead shark (Sphyrna lewini) as threatened or endangered under the ESA throughout its entire range, or, as an alternative, to delineate the species into DPSs. On November 28, 2011, we published a notice that listing of scalloped hammerhead sharks may be warranted, and we commenced a status review. The proposed rule to list and status review published in April 2013.
Key Documents
(All documents are in PDF format.)
| Title | Federal Register | Date |
|---|---|---|
| Scalloped Hammerhead Shark Status Review Report | 04/2013 | |
Proposed Endangered and Threatened Listing Determinations for 4 Distinct Population Segments (DPSs)
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78 FR 20717 | 04/05/2013 |
Negative 12-month finding for 2 DPSs
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78 FR 20717 | 04/05/2013 |
| CITES Appendix II Proposal | 10/04/2012 | |
| New import and export requirements under CITES Appendix III inclusion [pdf] | 09/25/2012 | |
| 90-Day Finding on a Petition To List the Scalloped Hammerhead Shark as Threatened or Endangered and Initiation of Status Review | 76 FR 72891 | 11/28/2011 |
| Petition to List Under the ESA | n/a | 08/2011 |
Updated: April 30, 2013
