The Sultanate of Oman shark fishery: Species composition, seasonality and diversity

Abstract. The smoothtooth blacktip shark, Carcharhinus leiodon, is one of the rarest whaler shark species of the genus Carcharhinus, previously known only from the holotype collected over 100 years ago from the Arabian Sea coast of Yemen. Recent market surveys in the Persian (Arabian) Gulf rediscovered 25 specimens (,2% of individual sharks recorded) in Kuwait, ,3000 km away from the type location. This study combined morphometric and molecular approaches to provide a detailed redescription of this species based on new material, as well as the first information on fresh colouration, size range and maturity. Sequences from two separate regions of the mitochondrial genome (COI and ND2) support the identity of C. leiodon as a distinct species, closely related to C. limbatus, C. amblyrhynchoides and C. tilstoni. Carcharhinus leiodon is superficially similar to, but clearly distinct from, C. melanopterus and C. amblyrhynchoides. The previously uncertain type locality of C. leiodon is considered to be correct, and the narrow range and unusual disjunct distribution, relatively rare for a marine carcharhinid, is discussed. The Kuwait population of C. leiodon, including juveniles, is subject to fisheries by-catch and is in an area of extensive habitat alteration. As a result, C. leiodon is considered vulnerable, requiring urgent conservation action.

Section: Distribution and Abundancementioning

confidence: 95%

Section: Conservationmentioning

confidence: 99%

Rediscovery and redescription of the smoothtooth blacktip shark, Carcharhinus leiodon (Carcharhinidae), from Kuwait, with notes on its possible conservation status

Moore

White

Ward

et al. 2011

“…As such, carcharhinids form a major component of the targeted commercial catch of elasmobranchs within these waters (Henderson et al 2007;White 2007;Harry et al 2011b). Life-history parameters such as maximum total length, growth rates and length and age at maturity show considerable variation within the Carcharhinidae (Stevens and McLoughlin 1991;Last and Stevens 2009).…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported in moderate numbers from commercial and artisanal shark fisheries from Indonesia (White 2007), the Maldives (Anderson and Ahmed 1993), Oman (Henderson et al 2007) and eastern Australia (Harry et al 2011b). Although limited research has been conducted on the biology of the species, L. macrorhinus has demonstrated regional variations in reproductive characteristics, with length at maturity ,600 mm TL in northern Australia (Stevens and McLoughlin 1991) and ,820 mm TL in Indonesia (White 2007).…”

Section: Introductionmentioning

confidence: 99%

Life-history traits of a small-bodied coastal shark

Gutteridge

Huveneers

Marshall³

et al. 2013

Abstract. The life histories of small-bodied coastal sharks, particularly carcharhinids, are generally less conservative than those of large-bodied species. The present study investigated the life history of the small-bodied slit-eye shark, Loxodon macrorhinus, from subtropical Hervey Bay, Queensland, and compared this species' biology to that of other coastal carcharhinids. The best-fit age model provided parameters of L N ¼ 895 mm total length (TL), k ¼ 0.18 and t 0 ¼ À6.3 for females, and L N ¼ 832 mm TL, k ¼ 0.44 and t 0 ¼ À2.6 for males. For sex-combined data, a logistic function provided the best fit, with L N ¼ 842 mm TL, k ¼ 0.41 and a ¼ À2.2. Length and age at which 50% of the population was mature was 680 mm TL and 1.4 years for females, and 733 mm TL and 1.9 years for males. Within Hervey Bay, L. macrorhinus exhibited an annual seasonal reproductive cycle, producing an average litter of 1.9 AE 0.3 s.d. With the exception of the low fecundity and large size-at-birth relative to maximum maternal TL, the life-history traits of L. macrorhinus are comparable to other small-bodied coastal carcharhinids, and its apparent fast growth and early maturation contrasts that of large-bodied carcharhinids.

“…Artisanal and commercial fisheries for carcharhiniform sharks exist in most equatorial and tropical regions and are particularly common throughout Asia, especially in the Indo-Pacific region and the Indian subcontinent (Kasim 1991;Hanfee 1999;Henderson et al 2007;White 2007), as well as parts of Africa, the Caribbean, and throughout central America (Motta et al 2005), notably Mexico (Castillo-Géniz et al 1998). Despite the important contribution these fisheries make to regional economies and food security, management of such fisheries is often neglected (Fowler et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Evaluating catch and mitigating risk in a multispecies, tropical, inshore shark fishery within the Great Barrier Reef World Heritage Area

Harry¹,

Tobin²,

Simpfendorfer³

et al. 2011

Abstract. Small-scale and artisanal fisheries for sharks exist in most inshore, tropical regions of the world. Although often important in terms of food security, their low value and inherent complexity provides an imposing hurdle to sustainable management. An observer survey of a small-scale commercial gill-net fishery operating within the Great Barrier Reef World Heritage area revealed at least 38 species of elasmobranch were present in the catch. Of the total elasmobranch catch, 95% was 25 species of Carcharhiniformes from the families Carcharhinidae, Hemigaleidae and Sphyrnidae. Individual species were captured in a variety of ways by the fishery, often with strongly biased sex ratios and in a variety of life stages (e.g. neonates, juveniles, adult). Despite this, the main carcharhiniform taxa captured could be qualitatively categorised into four groups based on similar catch characteristics, body size and similarities in life history: small coastal (,1000 mm); medium coastal (1000-2000 mm); large coastal/semi-pelagic (.2000 mm); and hammerheads. Such groupings can potentially be useful for simplifying management of complex multispecies fisheries. The idiosyncrasies of elasmobranch populations and how fisheries interact with them provide a challenge for management but, if properly understood, potentially offer underutilised options for designing management strategies.