|Scientific Name:||Carcharhinus leiodon Garrick, 1985|
|Taxonomic Source(s):||Garrick, J.A.F. 1985. Additions to a revision of the shark genus Carcharhinus: synonymy of Aprionodon and Hypoprion, and description of a new species of Carcharhinus. NOAA Tech. Rep., Nat. Mar. Fish. Serv. (34), 14 fig., 4 tab. Cited record from Guyana.|
|Red List Category & Criteria:||Endangered A2cd+3cd ver 3.1|
|Assessor(s):||Simpfendorfer, C., Jabado, R., Valinassab, T., Elhassan, I. & Moore, A.|
|Reviewer(s):||Pollom, R. & Kyne, P.M.|
|Facilitator/Compiler(s):||Jabado, R., Kyne, P.M.|
The Smoothtooth Blacktip Shark (Carcharhinus leiodon) is endemic to the Arabian Seas region and was only rediscovered in 2009. Overall, there are a limited number of specimens reported. It is believed to occur in inshore waters where it is captured in gillnet, line and trawl fisheries within its range. Its recent re-discovery and re-description means that historically it has likely been under-recorded, however reliable identification of Carcharhinus species since then indicates that this species is rare and localised.
Although there are limited data on its status, similar commercially important Carcharhinus species in the Arabian Gulf/Persian Gulf (hereafter referred to as the 'Gulf') have undergone significant declines. One of the areas in which the Smoothtooth Blacktip Shark is known from (southern Oman/eastern Yemen) has been, and continues to be, subject to intensive fishing targeted at sharks, suggesting suspected population declines of 50-80% are appropriate for this species. The other known centre of abundance around Kuwait is also subject to habitat degradation and change from water management practices in the Tigris and Euphrates rivers. Furthermore, the loss and modification of coastal habitats in the Gulf is a significant concern for inshore species such as this. A further population reduction is suspected over three generation lengths (2017-2042) based on current levels of exploitation. The limited geographic range of this species compared to other similar "blacktip" species increase the risks to this species. As such it is assessed as Endangered under criterion A2cd+3cd. Further research and monitoring are required to better understand the distribution, biology, ecology and population status of this species.
|Previously published Red List assessments:|
|Range Description:||The Smoothtooth Blacktip Shark is endemic to the Arabian Seas region, occurring in the northern Indian Ocean, including the Gulf (UAE, Kuwait, Bahrain), Sea of Oman and Arabian Sea (Oman and Yemen).|
Native:Bahrain; Kuwait; Oman; Qatar; United Arab Emirates; Yemen (South Yemen)
|FAO Marine Fishing Areas:|
Indian Ocean – western
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The Smoothtooth Blacktip Shark is morphologically very similar to the Blacktip Shark (C. limbatus), Spottail Shark (C. sorrah) and the Graceful Shark (C. amblyrhynchoides) and there is likely to have been confusion in species identification across its potential range. It was only recently rediscovered in Kuwaiti landings (2009), with subsequent confirmed records across the Gulf and in Oman (Moore et al. 2013). There is no species-specific information on population size or structure.|
Fisheries in the region have experienced increased demand for sharks since the 1970s due to the shark fin trade and as a result, effort is increasing in traditional shark fisheries in many areas (Bonfil 2003, Henderson et al. 2007, Jabado et al. 2015). Reports from Iran based on a comparison of results from trawl surveys in the Gulf indicate that the biomass of sharks (particularly carcharhinids) has been decreasing since the 1970s (Valinassab et al. 2006). Historical surveys in the Gulf indicated that carcharhinid sharks comprised up to 22% of biomass in trawl surveys in 1980-81, whereas in 2002, they represented only ~2% (Valinassab et al. 2006). Similarly, results from interviews with fishermen in the UAE indicate that the majority of fishers started seeing a decline in the abundance of sharks over 20 years ago, and that these declines have been significant (Jabado et al. 2015). Declines in the order of 30-50% in commercially important shark species such as C. limbatus and C. sorrah are suspected. Furthermore, one of the areas in which Smoothtooth Blacktip Shark is known from (southern Oman/eastern Yemen) has been, and continues to be, subject to intensive targeted shark fishing (Bonfil 2001). Therefore, although the status of the Smoothtooth Blacktip Shark remains unknown, based on the significant decline in other similar species in the region, population declines of 50–80% are suspected over a period of three generation spans (~25 years). A further population reduction is suspected over three generation lengths (2017–2042) based on current levels of exploitation.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||There is limited information available on this species because of the limited number of specimens recorded. Its maximum size is 165 cm total length (TL) (Weigmann 2016). Females are mature by at least 131 cm TL and demonstrate placental viviparity with litters of 4-6 embryos. In the northwestern Gulf, there is evidence that parturition occurs in spring when embryos are 35-51 cm TL. Further records of the Smoothtooth Blacktip Shark from the western Arabian Sea indicate that adults are present in this region throughout the year.|
No ageing data are available for the Smoothtooth Blacktip Shark. Generation length is estimated to be 8.25 years based on the Spottail Shark from Australia which has a similar maximum size. The Spottail Shark matures at 2-3 years and reaches a maximum age of 14 years (Davenport and Stevens 1988).
|Continuing decline in area, extent and/or quality of habitat:||Unknown|
|Generation Length (years):||8.25|
|Use and Trade:||
The meat of this species may be sold fresh for human consumption at local markets in the region. In some countries, such as Oman and Yemen, the meat is cut into fillets, dried and salted for domestic sales or trade with neighbouring countries. Species with black fins such as this one have higher value fins and fetch higher prices (although still lower than hammerheads and guitarfishes) (Jabado et al. 2015).
|Major Threat(s):||The Smoothtooth Blacktip Shark is likely to be taken by inshore gillnet, line and trawl fisheries within its range given it is known only from specimens from fish markets (Moore et al. 2013, Jabado et al. 2015). One of the known centres of abundance around Kuwait is also subject to habitat degradation and change from water management practices in the Tigris and Euphrates rivers (Moore et al. 2013). 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) which is likely to impact this species.|
There are no species-specific conservation measures in place. Some countries across its range have banned the targeted fishing for sharks (e.g., Kuwait and Saudi Arabia). Seasonal bans on shark fishing are in place in Iran (from March to August) and the UAE (February to June). The UAE, Qatar and Oman have banned trawling in their waters (since 1980, 1993 and 2011, respectively) while Iran, Kuwait and Saudi Arabia have seasonal trawl bans that might benefit the species. However, incidental catches occur in other fisheries (e.g., gillnetting). Finning has also been banned in the UAE, Oman and Iran, yet trade surveys indicate that some trade in the fins and meat of this species still occurs.
Research is needed to determine distribution, population size and trends in abundance to further assess status and any future conservation needs.
Effective monitoring of fisheries is required, as is the effective implementation and management of marine protected areas. An education program on sustainable fishing and bycatch mitigation is needed for fishers.
Bonfil, R. 2003. Consultancy on Elasmobranch Identification and Stock Assessment in the Red Sea and Gulf of Aden. Regional Organization for the Conservation of the Environment of the Red Sea and Gulf of Aden.
Davenport, S. and Stevens, J.D. 1988. Age and growth of two commercially important sharks (Carcharhinus tilstoni and C. sorrah) from Northern Australia. Australian Journal Marine Freshwater Research 39: 417-433.
Henderson, A.C., McIlwain, J.L., Al-Oufi, H.S. and Al-Sheili, S. 2007. The Sultanate of Oman shark fishery: Species composition, seasonality and diversity. Fisheries Research 86: 159-168.
IUCN. 2017. The IUCN Red List of Threatened Species. Version 2017-2. Available at: www.iucnredlist.org. (Accessed: 14 September 2017).
IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.
Jabado, R.W., Al Ghais, S.M., Hamza, W. and Henderson, A.C. 2015. The shark fishery in the United Arab Emirates: an interview based approach to assess . Aquatic Conservation: Marine and Freshwater Ecosystems 25(6): 800-816.
Jabado, R.W., Al Ghais, S.M., Hamza, W., Henderson, A.C., Spaet, J.L.Y., Shivji, M.S. and Hanner, R.H. 2015. The trade in sharks and their products in the United Arab Emirates. Biological Conservation 181: 190-198.
Moore, A.B.M., Almojil, D., Harris, M., Jabado, R.W. and White, W.T. 2013. New biological data on the rare, threatened shark Carcharhinus leiodon (Carcharhinidae) from the Persian Gulf and Arabian Sea. Marine and Freshwater Research 65(4): 327-332.
Sheppard, C., Al-Husiani, M., Al-Jamali, F., Al-Yamani, F., Baldwin, R., Bishop, J., Benzoni, F. and Dutrieux, E. 2010. The Gulf: A young sea in decline. Marine Pollution Bulletin 60: 13-38.
Valinassab, T., Daryanabard, R., Dehghani, R. and Pierce, G.J. 2006. Abundance of demersal fish resources in the Persian Gulf and Oman Sea. Journal of the Marine Biological Association of the United Kingdom 86: 1455-1462.
Weigmann, S. 2016. Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyes) of the world, with a focus on biogeographical diversity. Journal of Fish Biology 88(3): 837-1037.
|Citation:||Simpfendorfer, C., Jabado, R., Valinassab, T., Elhassan, I. & Moore, A. 2017. Carcharhinus leiodon. The IUCN Red List of Threatened Species 2017: e.T39371A109876922.Downloaded on 24 June 2018.|
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