Elasmobranchs (sharks and rays) have been apex predators in aquatic ecosystems for over 400 million years. In contrast to most bony fishes, elasmobranchs generally have life history characters that severely restrict the ability of populations to recover from anthropogenic causes of mortality. Intensive and expanding fisheries, driven by a growing human population and the
shark fin trade, have resulted in major declines in elasmobranch populations globally. With an increasing realisation of the vulnerability of elasmobranchs - and that scientific data to help inform their sustainable management were severely lacking - recent years have seen relevant studies flourish. However, much of this work has been limited geographically, with vast marine areas - particularly those associated with developing nations - still largely unknown.
The Persian (Arabian) Gulf represents one such area, despite being a unique marine environment surrounded by wealthy nations with significant fisheries interests. The handful of previous studies providing useful elasmobranch data are either geographically limited, or outdated, or both. An exhaustive literature review was undertaken (Rev. Fish Biol. Fisheries (2012) 22: 35-61), which collated scattered data from a wide range of sources including published scientific studies, 'grey' literature, and those from other disciplines such as archaeology and historical accounts. While seemingly disparate, these data were distilled into a coherent and comprehensive synthesis that i) provides a single foundation source for future researchers of Gulf elasmobranchs ii) identifies key concerns and realistic research priorities iii) identifies novel ideas, such as the possibly overlooked biogeographic importance of the region to elasmobranchs. The literature review was important in demonstrating that even without
targeted field studies, a large amount of less 'useful' desk-based data can collectively identify areas of interest relevant to management and conservation.
Complementing this desk-based work, the first major survey of the diversity, biology and fisheries of Gulf elasmobranchs was undertaken through intensive visits to fish markets and landing sites in Kuwait, Qatar and Abu Dhabi Emirate (/. Fish Biol. 80: 1619-1642). The elasmobranch fauna in landings was distinctive, and included species that are undescribed, rare and have a highly restricted known distribution. Numerical abundance was dominated by sharks (c. 80%), of which carcharhinids were by far the most important. The milk shark Rhizoprionodon acutus and whitecheek shark Carcharhinus dussumieri together comprised just under half of all recorded individuals. Around 90% of recorded sharks were small (50-90 cm total length, L1-) individuals, most of which were mature individuals of species with a small maximum size (<100 cm LT), although immature individuals of larger species (e.g. Carcharhinus
sorrah and other Carcharhinus spp.) were also important. The first size, sex and maturity data for a wide range of Gulf elasmobranch species are presented and include some notable differences from other locations in the Indo-West Pacific Ocean. A number of concerns regarding the sustainability of the fishery were highlighted by this study, notably that most of the batoid species recorded are classed by the IUCN Red List as vulnerable, endangered, data deficient or
not evaluated. Despite their considerable elasmobranch landings, none of the three countries sampled have developed an FAO 'Shark Plan', and Kuwait and Qatar currently report zero or no elasmobranch landings to the FAO.
Without a clear understanding of the biodiversity present in any ecosystem, management or conservation efforts are significantly hampered. Previous reports of the Gulf's elasmobranch fauna have been fragmentary, erroneous (Zootaxa (2007) 1591: 67-68) and confusing. The present work corrects these errors, and significantly advances a robust elasmobranch inventory for the Gulf based on accountable evidence such as museum specimens, genetic samples (using the
mitochondrial COI 'barcoding' gene) from market surveys, and historic and recent
photographs. In addition to that already known, the occurrence of a further 15 elasmobranch species in the Gulf is confirmed based on new evidence (Afr. J. Mar. Sci. (2012) 34: 297-301; Zool. Mid. East. (2010) 49: 101-103 and 50: 83-88). Major findings were the rediscovery in Kuwait of the very rare smoothtooth blacktip shark Carcharhinus leiodon, previously known only from a
single specimen collected in Yemen (3000 km away) in 1902 (Mar. Fresh. Res. (2011) 62: 528-539); and the description of a new species of whipray (Zootaxa (2012) 3327: 20-32), which may be endemic. The first evidence-based checklist of Gulf shark species was also collated, which not only lists those species reliably recorded but also those that have previously been reported without evidence (Zootaxa (2012) 3167, 1-16).