Elasmobranchs of the Persian (Arabian) Gulf: ecology, human aspects and research priorities for their improved management

Abstract

Given widespread concern about the status of elasmobranch fishes globally, information on this group in the Persian (Arabian) Gulf is reviewed comprehensively for the first time. The Arabian region may be of overlooked significance to elasmobranch biogeography, and the environmentally unique Gulf has some highly distinctive elements of biodiversity: an endemic and critically endangered rajid skate, a rarely recorded carcharhinid shark, and preliminary molecular studies which indicate intriguing levels of distinctness from conspecifics elsewhere in the IndoPacific. Elasmobranchs also have a long history of association with, and exploitation by, humans around the Gulf. Despite this, Gulf elasmobranchs have been poorly researched, probably due to their low esteem as food. Information is scattered through a variety of literature, and only a handful of published works have been primarily concerned with aspects relevant to management. Key areas of concern include large reported landings by Iran; the export of fins to east Asian markets (particularly through the United Arab Emirates); potentially increasing demand for elasmobranchs for pharmaceutical products and human consumption; a reported change in elasmobranch community structure along the Iranian coast; and major degradation of the Gulf's shallow, semienclosed environment. Priorities for research in the near future should include: resolution of taxonomic issues; species-level monitoring and reporting of fisheries landings by all Gulf states (including the species, pathways and fisheries involved in the fin trade locally); establishing the degree of connectivity of Gulf populations to those in adjacent waterbodies; and identification of key spatio-temporal sensitivities.

Ongoing decline of shark populations in the Eastern Red Sea

“…1), which are considered relatively undisturbed with only moderate recreational and extractive use of coastal resources (Klaus et al, 2008). Due to great political and logistical constraints, sampling was conducted opportunistically between March 8th, 2011 andMarch 19th, 2013. Table 1 includes geographic details and sampling effort of all sampling locations.…”

“…Unsustainable fishing and overexploitation of shark resources coupled with a severe lack of enforced protection strategies is a common scenario in the Arabian Seas region (Henderson et al, 2007;Moore, 2011;Jabado et al, 2015). Such regional overexploitation of marine resources is especially worrisome in light of shared stock structures, as demonstrated genetically for a range of the most commonly landed shark species throughout the region .…”

Contribution to the Taxonomy and Distribution of Six Shark Species (Chondrichthyes, Elasmobranchii) from the Gulf of Thailand

“…Generally, Chiloscyllium griseum is considered a taxonomically complex species and the differentiation of several species of Chiloscyllium remains difficult due to strong ontogenetic changes and a high margin of variation in some morphometric ratios [19,47].…”

Extensive use of mesopelagic waters by a Scalloped hammerhead shark (Sphyrna lewini) in the Red Sea

“…Furthermore, S. lewini represents over 3% of all species traded in the Arabian Seas region [17]. At the same time, S. lewini populations in the western Indian Ocean appear fragmented with limited dispersal between the Arabian Seas region and other Indian Ocean regions [18]; yet, stock assessments and species-specific studies are missing in the area [19,20]. Gathering ecological information of movement data is a critical first step toward appropriate management strategies of shark species, and several studies have examined movements of S. lewini in different ocean systems (e.g., [21][22][23][24][25][26][27]).…”