Please note, this National Red List website contains a subset of data whilst we transition to national focal point driven data uploads. We thank you for your patience with this and welcome national contributors to get in touch to update their national dataset. Terms of Use including citation guidance are found here.

The previous dataset is available via: https://archive.nationalredlist.org/. This site is no longer updated but can help with most enquiries whilst we focus on redevelopment.

NRLD - 329871 | Sphyrna lewini

Assessment ID
329871
Taxon name
Sphyrna lewini
(Griffith & Smith, 1834)
Uploaded by
National Red List Database
Taxonomic information
Scientific name
Sphyrna lewini
(Griffith & Smith, 1834)
Assessed taxon level
Species
Higher level taxonomic groupings
Vertebrates
Fishes
Kingdom
Animalia
Phylum
chordata
Class
chondrichthyes
Order
carcharhiniformes
Family
sphyrnidae
Genus
Sphyrna
Species
lewini
Species authority
(Griffith & Smith, 1834)
Location and scope
Specific locality or subnational name or regional name
United Arab Emirates (the)
Scope (of the Assessment)
National
Countries included within the scope of the assessment
United Arab Emirates (the)
Country ISO code(s)
ARE
Does the assessment cover a marine EEZ area(s)?
Not_assigned
Conservation Status
Assessed as
Endangered
Abbreviated status
EN
Qualifying criteria (if given)
A2d
Criteria system used
IUCN

(see Assessment details)

Assessment rationale/justification
The Scalloped Hammerhead occurs throughout UAE inshore and offshore waters, and is apparently infrequently captured there. Capture of this species is totally banned in the UAE. All life-stages of this species are vulnerable to capture in both targeted and incidental fisheries that occur in both coastal areas as well as oceanic. Although there are limited data on its status, other shark species in the Arabian Gulf have undergone significant declines due to exploitation. 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. There is evidence that a distinct subpopulation of this species occurs in the Arabian Sea region. Based on recorded levels of exploitation, it is suspected to have declined by at least 50% over the past three generation lengths, or about 72 years. It is listed as Endangered A2d.
Assessment details
Year assessed
2019
Assessors/contributors/reviewers listed
UAE National Red List Workshop
Criteria system used
IUCN
Reference for methods given
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.
Further information
Endemism (according to assessment)
Endemic to region
Not assigned
Taxon distribution as listed in assessment
The Scalloped Hammerhead occurs throughout UAE waters. Elsewhere, it is circumglobally distributed in coastal warm temperate and tropical seas (Last and Stevens 2009).
Is there a map available in assessment?
Yes
Habitat and systems
Ecological system type
Terrestrial
Not_assigned
Freshwater
Not_assigned
Marine
Yes
Habitat
Habitat details as listed in assessment
The Scalloped Hammerhead is a coastal and semi-oceanic pelagic shark, found over continental and insular shelves and in deep water ranging from intertidal areas and the surface to at least 1,000 m depth (Compagno et al. 2005). Horizontal migration is observed from inshore bays to a pelagic habitat as this species grows. It has been observed to be highly faithful to particular diurnal core areas (Holland et al. 1993) and sometimes form large schools which migrate to higher latitudes in summer (Stevens and Lyle 1989). This species segregates by sex, with females migrating offshore earlier and at smaller sizes than males. Adults spend most of the time offshore in midwater and females migrate to the coastal areas to have their pups (Bass et al. 1975, Klimley and Nelson 1984, Branstetter 1987, Klimley 1987, Chen et al. 1988, Stevens and Lyle 1989). Nursery areas are found in shallow inshore waters, while the adults are found offshore (Compagno 1984, Holland et al. 1993, Kotas et al. 1995, Lessa et al. 1998). Neonates and juveniles are known to shoal in confined coastal pupping areas for up to two years before moving out to adult habitat (Holland et al. 1993). The species is viviparous with a yolk-sac placenta. Only the right ovary is functional. In Taiwanese (POC) waters, ovum development takes approximately 10 months and ova reach a maximum diameter of 40-45 mm. The number of oocytes in the ovarium can be as many as 40-50 per female (Chen et al. 1988). The gestation period is around 9-12 months, with birth in spring and summer. The average number of embryos in the uterus ranges from 12-41 and females pup every year. Newborn size ranges from 31-57 cm (Castro 1983, Compagno 1984, Branstetter 1987, Chen et al. 1988, Stevens and Lyle 1989, Chen et al. 1990, Oliveira et al. 1991, 1997, Amorim et al. 1994, White et al. 2008). Maximum size is reported by several studies, 370-420 cm total length (TL) (Ebert et al. 2013) and ranged from 219-340 cm TL for males and 296-346 cm TL for females (Bass et al. 1975b, Schwartz 1983, Klimley and Nelson 1984, Stevens 1984, Branstetter 1987, Chen et al. 1988, Stevens and Lyle 1989, Chen et al. 1990). Males mature between 140-198 cm TL and females at around 200-250 cm TL (Compagno 1984b, Branstetter 1987, Chen et al. 1990, Carrera and Martinez 2007, White et al. 2008). Branstetter's (1987) growth study in the Gulf of Mexico found asymptotic length for both sexes of 329 cm TL and 253 cm fork length (FL), with an index of growth rate of k = 0.073 y<sup>-1</sup>. Piercy et al.'s (2007) more recent study used FL rather than TL and suggested faster growth, with asymptotic length of 214.8 cm FL for males and 233.1 cm FL for females, with an index growth rate of k=0.13 year<sup>-1</sup> for males and k=0.09 year<sup>-1</sup> for females. It is unclear whether these differences are related to sample size, methodology or changes resulting from a density-dependent compensatory response to population depletion. The nearest studies on life history traits of this species have been undertaken in the Eastern Indian Ocean. White et al. (2008) estimated females and males to mature at 228.5 cm TL and 175.6 cm TL, respectively. Age at maturity was estimated at 13.2 for females and 8.9 years for males (Drew et al. 2015). Based on these data, generation length was estimated at 24 years.
Threats and conservation measures listed
Threats listed in assessment
Information pertaining to threats specific to the UAE are unavailable. This species is impacted by target (for fins and their valuable meat) and bycatch fisheries that are active elsewhere in its range. 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). Furthermore, aggregating behaviour and low survival at capture causes this species to be very susceptible to fishing pressure, and the recolonisation of depleted areas is expected to be a slow and complex process (Maguire et al. 2006, Drew et al. 2015).
Publication
Ralph, G.M., Stump, E., Linardich, C., Bullock, R.W., Carpenter, K.E., Allen D.J., Hilton-Taylor, C., Al Mheiri, R., and Alshamsi, O. 2021. UAE National Red List of Marine Species: Reef-building corals, cartilaginous fishes and select bony fishes. 2021. Ministry of Climate Change and Environment, Dubai, United Arab Emirates.