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South, Turks and Caicos Islands

Omori K.L.,Virginia Institute of Marine Science | Hoenig J.M.,Virginia Institute of Marine Science | Luehring M.A.,Great Lakes Indian Fish and Wildlife Commission | Baier-Lockhart K.,Center for Marine Resource Studies
Fisheries Research

Fisheries can be managed based on surplus production models when only catch and effort data are available. However, reported catch and effort may not equal the true values. We studied the effects of jointly underestimated catch and effort on surplus production model parameter estimates (e.g., MSY, Bmsy and Fmsy) as well as estimates of key ratios (e.g., F/Fmsy). We used ASPIC to examine various scenarios of underreporting for three example fisheries, North Atlantic swordfish, northern pike in Minnesota and queen conch in the Turks and Caicos Islands. With constant underestimation of catch and effort throughout time, MSY, Bmsy and Bnext are all underestimated by the same percentage, while Flast and the ratios, F/Fmsy and B/Bmsy, are not affected. As a result, harvest regulations can be set based on fishing mortality and the ratios. That is, when one thinks the harvest is MSY with F = Fmsy, one is achieving MSY and Fmsy even though the catch is actually larger than it is thought to be. However, increasing or decreasing trends in underreporting of catch and effort over time lead to errors in the parameter and ratio estimates whose direction is case-specific and whose magnitude can be high or low. Each fishery model responded differently to the simulated scenarios, which may be a result of different exploitation histories or the quality of the fit of the production model to the data. The wide range of outcomes observed may be due to the fact that underestimation of catch and effort can lead to a gain or reduction in data contrast. Simulations of a variety of possible scenarios similar to the methods in this study should be conducted if catch and effort are believed to be underestimated to determine how the surplus production model responds. © 2016 Elsevier B.V. Source

Jabado R.W.,United Arab Emirates University | Jabado R.W.,Gulf | Al Ghais S.M.,United Arab Emirates University | Hamza W.,United Arab Emirates University | And 2 more authors.
Marine Biodiversity

Although fish fauna in the Arabian/Persian Gulf have been studied for decades, shark diversity has only been recently investigated in the region. Here, we present a first comprehensive account of shark diversity from the United Arab Emirates based on fishery-dependent data collected at market and landing sites over a two-year period of field sampling. Landings across the country were dominated by carcharhinids, and six species were found to be most abundant, including the spot-tail shark, Carcharhinus sorrah, and the milk shark, Rhizoprionodon acutus, contributing 31.8 % and 29.9 %, respectively, of the total number of sharks. While observed landings varied among regions and across seasons, results showed that shark landings were dominated by small-sized species, which may be a reflection of overexploitation. We are now expanding the existing checklist of shark species in the Persian Gulf from 27 to 31, having utilized both morphological identification and genetic barcoding in validating the existence of the grey bamboo shark, Chiloscyllium griseum; the tawny nurse shark, Nebrius ferrugineus; the silky shark, Carcharhinus falciformis; and the sandbar shark, Carcharhinus plumbeus, in these waters. This inventory provides an urgently needed assessment of current regional diversity patterns that can now be used as a baseline for future investigations evaluating the effect of fisheries on shark populations. Results emphasize the need for research on life history traits of the various species in order to determine their regional conservation status, but also reveal that a precautionary approach to conservation will be necessary to mitigate anthropogenic impacts. © 2014 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg Source

Jabado R.W.,United Arab Emirates University | Al Ghais S.M.,United Arab Emirates University | Hamza W.,United Arab Emirates University | Henderson A.C.,Center for Marine Resource Studies
Aquatic Conservation: Marine and Freshwater Ecosystems

Anecdotal evidence suggests that sharks are being targeted in the United Arab Emirates artisanal fishery. However, little information is available on this fishery and baseline information is essential for understanding its impact on shark populations in the Arabian/Persian Gulf, and for managing sharks in this region. The aim of this study was to investigate the artisanal shark fishery and gain an insight into the social, motivational and economic drivers behind it. Fishery characteristics were examined and the effect of fishing on local shark stocks assessed by interviewing Emirati fishermen across the country (n = 126). Sharks were found to be increasingly targeted owing to their high value in the global fin trade industry. The majority of fishermen (80%) confirmed that changes in species composition, abundance and sizes of sharks have been continuing for more than two decades, mainly because of overfishing, raising concerns about the sustainability of this fishery. Results suggest that sharks are likely to be overexploited and that management measures will need to take into account the precautionary principle. There is an urgent need to formulate long-term and effective conservation and management plans to prevent further declines in a number of species. Additional efforts should be directed to quantify the ecological implications of the observed changes and determine if these are aggravated by the life-history traits of the fished species. Such implications should be considered when assessing the sustainability of local fisheries. The data gathered can now serve as a reference to managers, fisheries scientists and other stakeholders to prioritize future research as well as lay foundations for the development and implementation of national management plans for the protection and conservation of sharks. © 2015 John Wiley & Sons, Ltd. Source

Robinson D.P.,University of Edinburgh | Jaidah M.Y.,Qatar Ministry of Environment | Jabado R.W.,United Arab Emirates University | Lee-Brooks K.,University of York | And 7 more authors.

Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. Density estimates of up to 100 sharks within an area of 1 km2 were recorded. Sharks ranged between four and eight metres' estimated total length (mean 6.92±1.53 m). Most animals observed were actively feeding on surface zooplankton, consisting primarily of mackerel tuna, Euthynnus affinis, eggs. © 2013 Robinson et al. Source

Jabado R.,United Arab Emirates University | Jabado R.,Gulf | Al Ghais S.,United Arab Emirates University | Hamza W.,United Arab Emirates University | And 2 more authors.
African Journal of Marine Science

Landing site and market surveys of sharks landed along the Arabian Gulf coast of the United Arab Emirates were undertaken between October 2010 and September 2012 to obtain biological data from this artisanal fishery. Data were collected on the size and sex of 12 482 individuals representing 30 species. Maximum sizes of Carcharhinus sorrah, C. amblyrhynchoides and Hemipristis elongata were extended by at least 300 mm total length (TL) compared with published global maxima. The size at 50% maturity was determined for males of five species and this indicated that the males of smaller shark species (<1 000 mm maximum TL) in the fishery were largely mature. For many species, including Loxodon macrorhinus and Mustelus mosis, overall sex ratios were male-biased, indicating that sexual segregation is likely in those species. Furthermore, sex ratios for several species, such as Rhizoprionodon acutus, showed differences across seasons. Overall, the landings contained a high proportion of juveniles, causing concerns about the sustainability of this fishery. Biological parameters of a number of species differed from those recorded earlier for the region, demonstrating a need for additional local data collection to support the development of management measures. © 2016 NISC (Pty) Ltd Source

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