Sphyrna mokarran | UAE National Red List of Marine Species: Reef-building corals, cartilaginous fishes and select bony fishes

Taxa
Sphyrna mokarran | (Rüppell, 1837)
Location
Countries in Assessment
United Arab Emirates
Country ISO code(s)
ARE
Does the assessment cover a marine EEZ area(s)?
Off
Scope (Assessment)
National
Taxon
Taxonomic Group
Vertebrates
Taxonomic Group Level 2
Fishes
Assessed taxon level
Species
Taxon distribution as listed in assessment
The Great Hammerhead occurs throughout UAE waters (Tourenq et al. 2008). Globally, it ranges widely throughout the tropical waters of the world from latitudes 40'°N to 35'°S (Last and Stevens 2009).
Habitats and Ecology
Ecological system type
Terrestrial system
No
Freshwater system
No
Marine system
Yes
Habitat
Habitat details as listed in assessment
The Great Hammerhead is a coastal-pelagic and semi-oceanic tropical hammerhead shark occurring close inshore and well offshore, over continental shelves, island terraces, and in passes and lagoons of coral atolls, as well as over deep water near land, at depths ranging from near-surface to over 80 m (Compagno et al. 2005). The maximum total size is 550-610 cm total length (TL) (Weigmann 2016), though 400 cm TL is more common for a mature adult (Compagno et al. 2005, Last and Stevens 1994). Males mature at about 225 to 269 cm TL, and reach at least 341 cm TL, and females mature at about 225 to 300 cm TL and reach 482 to 549 cm TL (Compagno et al. 2005) In the UAE the largest recorded specimen was 3.82 m (Jabado et al. 2016 biological data sharks uae paper). The Great Hammerhead is viviparous, with a yolk-sac placenta. Litter size ranges from 6 to 42 pups after 11 months' gestation (Ebert et al. 2013). Size at birth is 50 to 70 cm TL with females breeding once every two years (Stevens and Lyle 1989). Generation length is estimated at 24-25 years based on Piercy et al. (2010) and Harry et al. (2011).
Is there a map available in assessment?
Yes
Assessed status
Asessment status in full
Endangered
Assessment status abreviation
EN
Assessment status criteria
A2d
Assessment rationale/justification
The Great Hammerhead occurs throughout UAE inshore and offshore waters, and is unlikely to be abundant wherever it occurs. Capture of this species is totally banned in the UAE. It is particularly susceptible to capture in gill net and longline fisheries and is highly valued for its fins. It suffers very high bycatch mortality, which causes it to be susceptible to population decline. While there is limited information available on this species in the region, its large size, valuable fins, and intensive fisheries mean that, like many other large sharks, it has undergone significant declines. It is apparently highly migratory, and has slow life history characteristics including low fecundity and a low annual rate of population increase. Considering this, the species has a low capacity to recover from even moderate levels of exploitation. It is especially susceptible to exploitation (target and bycatch) in many largely unregulated gill net, longline and trawl fisheries that operate within its range outside and surrounding UAE waters. Some management measures are now in place in the Arabian Sea region, although domestic fisheries are likely to continue. Though data specifically from the UAE are not available, individuals in the UAE are a component of a larger, interconnected and migratory population that occurs broadly in the north-western Indian Ocean. It is inferred that declines reported in the Arabian Sea region are representative of its status in the UAE. Based on recorded levels of exploitation, it is suspected to have declined by at least 50% over the past three generation lengths, or about 75 years. It is listed as Endangered A2d.
About the assessment
Assessment year
2019
Assessors/contributors/reviewers listed
UAE National Red List Workshop
Affliation of assessor(s)/contributors/reviewers listed on assessment
Government
IGO
Assessor affiliation specific
Government|IGO
Criteria system
Criteria system specifics
IUCN v3.1
Criteria system used
IUCN
Criteria Citation
IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1, Second edition. IUCN, Gland, Switzerland and Cambridge, UK. iv + 32pp pp. And IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN. iii + 41pp.
Endemism
Endemic to region
Not_assigned
Endemism Notes
Is an endemic?: Not_assigned
Conservation
Threats listed in assessment
Information pertaining to threats specific to the UAE are unavailable. This species is impacted by bycatch fisheries that are active elsewhere in its range. Marine habitats in the Gulf are experiencing high levels of disturbance and quickly deteriorating due to major impacts from development activities (including dredging and reclamation), desalination plants, industrial activities, habitat destruction through the removal of shallow productive areas and major shipping lanes (Sheppard et al. 2010). Low survival at capture makes this species very vulnerable to fishing pressure, whether directed or incidental. Finning and discarding of carcasses has also been reported, especially in offshore and high seas fisheries (Anderson and Simpfendorfer 2005). This species is being increasingly targeted in some areas in response to increasing demand for the fins (Jabado et al. 2015). Corals in the UAE and Arabian Gulf have severely declined due to the increasing frequency of mass bleaching events caused by rising water temperatures, which is a consequence of climate change, as well as pervasive coastal development (Riegl et al. 2018, Burt et al. 2019).
Conservation Measures

Conservation measures:
Conservation measures notes:
Required conservation measures:

Scientific Name Kingdom Phylum Class Order Family Genus
Sphyrna mokarran Animalia Chordata Chondrichthyes Carcharhiniformes Sphyrnidae Sphyrna