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Polynesians' detailed observations of shark behaviour encompass the notion of a divinity, the fleeting image of a sky god, as well as potential source of food and valued tools. Due to prevailing cosmogony, sharks benefited from being a taboo species, historically limiting their exploitation. We examine how the reputedly fierce warriors of ' Anaa (an atoll in Tuamotu archipelago, French Polynesia) came to be symbolically identified with a marine predator, being called \"Parata,\" the vernacular name of the oceanic whitetip shark Carcharinus longimanus. Both sharks and indigenous cultures are currently under threat in the East Pacific and we propose that an understanding of these sacred relationships could be used to help protect them.

Studies on reproduction in sharks are important for their management, since the attainment of sexual maturity has a substantial impact on their distribution, behaviour and biology. However, reproductive biology of large oceanic sharks is poorly studied in the Indian seas. In this study, the size structure, sex and maturity of pelagic thresher (Alopias pelagicus), bigeye thresher (A. superciliosus), oceanic whitetip shark (Carcharhinus longimanus), tiger shark (Galeocerdo cuvier), shortfin mako (Isurus oxyrinchus), longfin mako (I. paucus) and blue shark (Prionace glauca) in the eastern Arabian Sea are described based on 1449 specimens collected from gillnet-cum-longline landings at the Cochin fisheries harbour during 2013–2014. Sex ratios of sampled specimens were biased to males in pelagic thresher, bigeye thresher, tiger shark and blue shark, while females dominated in the specimens of oceanic whitetip shark. Females matured at greater lengths than males in all species except oceanic whitetip shark. Lengths at maturity for males were in the range of 189.05–286.56 cm, whereas those of females were in the range of 187.74–310.69 cm. Litter sizes of both the thresher shark species were always two, while in oceanic whitetip shark, litter size was 3–9 and 22–51 in tiger shark. Seasonal reproduction was noticed in oceanic whitetip shark and tiger shark. Pregnant females were not found in the blue shark, shortfin and longfin makos sampled during the study period. Reproductive aspects of pelagic thresher, bigeye thresher, oceanic whitetip shark, tiger shark, shortfin mako, longfin mako and blue sharks in the eastern Arabian Sea are generally consistent with earlier reports from other regions of the world's oceans. These preliminary findings should be useful to identify suitable management measures for the above shark species.

Protecting sharks from overexploitation has become global priority after widespread population declines have occurred. Tracking catches and trade on a species-specific basis has proven challenging, in part due to difficulties in identifying processed shark products such as fins, meat, and liver oil. This has hindered efforts to implement regulations aimed at promoting sustainable use of commercially important species and protection of imperiled species. Genetic approaches to identify shark products exist but are typically based on sequencing or amplifying large DNA regions and may fail to work on heavily processed products in which DNA is degraded. Here, we describe a novel multiplex PCR mini-barcode assay based on two short fragments of the cytochrome oxidase I (COI) gene. This assay can identify to species all sharks currently listed on the Convention of International Trade of Endangered Species (CITES) and most shark species present in the international trade. It achieves species diagnosis based on a single PCR and one to two downstream DNA sequencing reactions. The assay is capable of identifying highly processed shark products including fins, cooked shark fin soup, and skin-care products containing liver oil. This is a straightforward and reliable identification method for data collection and enforcement of regulations implemented for certain species at all governance levels.

Large-bodied pelagic ectotherms such as sharks need to maintain internal temperatures within a favourable range in order to maximise performance and be cost-efficient foragers. This implies that behavioural thermoregulation should be a key feature of the movements of these animals, although field evidence is limited. We used depth and temperature archives from pop-up satellite tags to investigate the role of temperature in driving vertical movements of 16 oceanic whitetip sharks, Carcharhinus longimanus , (OWTs). Spectral analysis, linear mixed modelling, segmented regression and multivariate techniques were used to examine the effect of mean sea surface temperature (SST) and mixed layer depth on vertical movements. OWTs continually oscillated throughout the upper 200 m of the water column. In summer when the water column was stratified with high SSTs, oscillations increased in amplitude and cycle length and sharks reduced the time spent in the upper 50 m. In winter when the water column was cooler and well-mixed, oscillations decreased in amplitude and cycle length and sharks frequently occupied the upper 50 m. SSTs of 28  o C marked a distinct change in vertical movements and the onset of thermoregulation strategies. Our results have implications for the ecology of these animals in a warming ocean.

An increasing awareness of the vulnerability of sharks to exploitation by shark finning has contributed to a growing concern about an unsustainable shark fishery. Taiwan's fleet has the 4th largest shark catch in the world, accounting for almost 6% of the global figures. Revealing the diversity of sharks consumed by Taiwanese is important in designing conservation plans. However, fins make up less than 5% of the total body weight of a shark, and their bodies are sold as filets in the market, making it difficult or impossible to identify species using morphological traits. In the present study, we adopted a DNA barcoding technique using a 391-bp fragment of the mitochondrial cytochrome oxidase I (COI) gene to examine the diversity of shark filets and fins collected from markets and restaurants island-wide in Taiwan. Amongst the 548 tissue samples collected and sequenced, 20 major clusters were apparent by phylogenetic analyses, each of them containing individuals belonging to the same species (most with more than 95% bootstrap values), corresponding to 20 species of sharks. Additionally, Alopias pelagicus, Carcharhinus falciformis, Isurus oxyrinchus, and Prionace glauca consisted of 80% of the samples we collected, indicating that these species might be heavily consumed in Taiwan. Approximately 5% of the tissue samples used in this study were identified as species listed in CITES Appendix II, including two species of Sphyrna, C. longimanus and Carcharodon carcharias. DNA barcoding provides an alternative method for understanding shark species composition when species-specific data is unavailable. Considering the global population decline, stock assessments of Appendix II species and highly consumed species are needed to accomplish the ultimate goal of shark conservation.

Accurate assessment of shark population status is essential for conservation but is often constrained by limited and unreliable data. To provide a basis for improved management of shark resources, we analyzed a long-term record of species-specific catches, sizes, and sexes of sharks collected by onboard observers in the western and central Pacific Ocean from 1995 to 2010. Using generalized linear models, we estimated population-status indicators on the basis of catch rate and biological indicators of fishing pressure on the basis of median size to identify trends for blue (Prionace glauca), mako (Isurus spp.), oceanic whitetip (Carcharhinus longimanus), and silky (Carcharhinus falciformis) sharks. Standardized catch rates of longline fleets declined significantly for blue sharks in the North Pacific (by 5% per year [CI 2% to 8%]), for mako sharks in the North Pacific (by 7% per year [CI 3% to 11%]), and for oceanic whitetip sharks in tropical waters (by 17% per year [CI 14% to 20%]). Median lengths of silky and oceanic whitetip sharks decreased significantly in their core habitat, and almost all sampled silky sharks were immature. Our results are consistent with results of analyses of similar data sets. Combined, these results and evidence of targeted fishing for sharks in some regional fisheries heighten concerns for sustainable utilization, particularly for oceanic whitetip and North Pacific blue sharks. Regional regulations that prohibit shark finning (removal of fins and discarding of the carcass) were enacted in 2007 and are in many cases the only form of control on shark catches. However, there is little evidence of a reduction of finning in longline fisheries. In addition, silky and oceanic whitetip sharks are more frequently retained than finned, which suggests that even full implementation of and adherence to a finning prohibition may not substantially reduce mortality rates for these species. We argue that finning prohibitions divert attention from assessing whether catch levels are sustainable and that the need for management of sharks should not be addressed by measures that are simple to implement but complex to enforce and evaluate. La evaluación precisa del estatus de las poblaciones de tiburón es esencial para la conservación pero a menudo es constreñida por datos limitados y poco confiables. Para proporcionar una base para un mejor manejo del recurso tiburón, analizamos un registro de largo plazo sobre la captura de especies, tamaños y sexos de tiburón recolectados por observadores a bordo de embarcaciones en el Pacífico occidental y central de 1995 a 2010. Utilizando modelos lineales generalizados, estimamos indicadores del estatus de la población con base en la tasa de captura e indicadores biológicos de la presión de pesca con base en tamaño medio para identificar tendencias para Prionace glauca, Isurus spp., Carcharhinus longimanus y Carcharhinus falciformis. Las tasas de captura estandarizadas declinaron significativamente para P. glauca en el Pacífico Norte (5% por año [IC 2% a 8%]), para I. spp. en el Pacífico Norte (7% por año [IC 3% a 11%] y para C. longimanus en aguas tropicales (17% por año [IC 14% a 20%]). Los tamaños medios de C. falciformis y C. longimanus decrecieron significativamente en su hábitat núcleo, y casi todos los individuos de C. falciformis eran inmaduros. Nuestros resultados son consistentes con los análisis de conjuntos de datos similares. Combinados, estos resultados y evidencia de la pesca de tiburones en algunas pesquerías regionales aumentan la preoocupación por el uso sustentable de tiburones, particularmente de C. longimanus y P. glauca, no son sustentables. En 2007 se decretaron regulaciones regionales que prohíben el cercenamiento de aletas de tiburón (remoción de aletas y eliminación del cuerpo) y en muchos casos son la única forma de control de la captura de tiburones. Sin embargo, hay poca evidencia de la reducción del cercenamiento en las pesquerías. Adicionalmente, C. longimanus y P. glauca son retenidos más frecuentemente que cercenados, lo que sugiere que aun con la implementación plena de y la adhesión a una prohibición de cercenamiento puede que no se reduzcan sustancialmente las tasas de mortalidad de estas especies. Argumentamos que las prohibiciones de cercenamiento desvían la atención de la evaluación de la sustentabilidad de los niveles de captura y que la necesidad del manejo de tiburones no debe ser abordada con medidas que son sencillas de implementar pero complejas de aplicar y evaluar.

There is a growing need to identify shark products in trade, in part due to the recent listing of five commercially important species on the Appendices of the Convention on International Trade in Endangered Species (CITES; porbeagle, Lamna nasus, oceanic whitetip, Carcharhinus longimanus scalloped hammerhead, Sphyrna lewini, smooth hammerhead, S. zygaena and great hammerhead S. mokarran) in addition to three species listed in the early part of this century (whale, Rhincodon typus, basking, Cetorhinus maximus, and white, Carcharodon carcharias). Shark fins are traded internationally to supply the Asian dried seafood market, in which they are used to make the luxury dish shark fin soup. Shark fins usually enter international trade with their skin still intact and can be identified using morphological characters or standard DNA-barcoding approaches. Once they reach Asia and are traded in this region the skin is removed and they are treated with chemicals that eliminate many key diagnostic characters and degrade their DNA (\"processed fins\"). Here, we present a validated mini-barcode assay based on partial sequences of the cytochrome oxidase I gene that can reliably identify the processed fins of seven of the eight CITES listed shark species. We also demonstrate that the assay can even frequently identify the species or genus of origin of shark fin soup (31 out of 50 samples).

Background The oceanic whitetip shark Carcharhinus longimanus (family Carcharhinidae) is one of the largest sharks inhabiting all tropical and subtropical oceanic regions. Due to their life history traits and mortality attributed to pelagic longline fishing practices, this species is experiencing substantial population decline. Currently, C. longimanus is considered by the IUCN Red List of Threatened Species as “vulnerable” throughout its range and “critically endangered” in the western north Atlantic. This study sequences and describes the complete mitochondrial genome of C. longimanus in detail. Methods and results The mitochondrial genome of C. longimanus was assembled through next-generation sequencing and then analyzed using specialized bioinformatics tools. The circular, double-stranded AT-rich mitogenome of C. longimanus is 16,704 bp long and contains 22 tRNA genes, 2 rRNA genes, 13 protein coding genes and a 1,065 bp long control region (CR). Out of the 22 tRNA genes, only one (tRNA-Ser1) lacked a typical ‘cloverleaf’ secondary structure. The prevalence of TTA (Leu), ATT (Ile) and CTA (Leu) codons in the PCGs likely contributes to the AT-rich nature of this mitogenome. In the CR, ten microsatellites were detected but no tandem repeats were found. Stem-and-loop secondary structures were common along the entire length of the CR. Ka/Ks values estimated for all PCGs were < 1, indicating that all the PCGs experience purifying selection. A phylomitogenomic analysis based on translated PCGs confirms the sister relationship between C. longimanus and C. obscurus . The analysis did not support the monophyly of the genus Carcharhinus . Conclusions The assembled mitochondrial genome of this pelagic shark can provide insight into the phylogenetic relationships in the genus Carcharhinus and aid conservation and management efforts in the Central Pacific Ocean.

Landing data are the most basic information used to manage fisheries, although they are often unavailable or incomplete. The objective of this work was to reconstruct the national database of marine commercial landings for the Brazilian industrial and artisanal fisheries, from 1950 to 2015. Total landings increased strongly from 1950 to mid-1980s and suffered sharp decline in the early 1990s, mainly associated to the collapse of sardine fisheries. After that, another period of increasing landings was observed, but at a much lower rate. Industrial landings always surpassed artisanal landings in Brazilian waters, except for the beginning of the time series, when many industrial fleets had not started yet, and in the early 2000s, when a change in the methodology for collecting landing statistics was implemented in the state of Pará leading to an overestimation of artisanal landings. Artisanal fisheries have been declining since 2005, which is worrisome due to the social impact it may have on local income and food security. Regional differences were also observed, with industrial landings being always higher than artisanal landings in southeastern-southern Brazil, while the opposite was true for the northern-northeastern regions. Higher landings were observed in the southeastern-southern regions when both artisanal and industrial fleets were combined. Sardine and demersal fishes were the main resources landed by industrial fishers. Artisanal fishers caught more species than their industrial counterpart, featuring Xiphopenaeus kroyeri , Cynoscion acoupa , and Ucides cordatus . Although the fishing of Epinephelus itajara was banned in Brazil, it continues to be landed. Yet, catches of this species and others under some threat status are still not properly registered, including: Carcharhinus longimanus , Galeorhinus galeus , Sphyrna lewini , Sphyrna mokarran , Pristis pectinata , and Pseudobatos horkelii . Fishing resources not identified in previous landing reconstruction efforts, such as sea urchins and sea cucumbers, have now been reported. The database presented here should be continuously updated and improved. It is of paramount importance to resume the collection of landing statistics, including information on fishing effort, to assess the relative impact of fisheries and environmental factors on the main Brazilian fishing stocks.

Animal behavior should optimize the difference between the energy they gain from prey and the energy they spend searching for prey. This is all the more critical for predators occupying the pelagic environment, as prey is sparse and patchily distributed. We theoretically derive two canonical swimming strategies for pelagic predators, that maximize their energy surplus while foraging. They predict that while searching, a pelagic predator should maintain small dive angles, swim at speeds near those that minimize the cost of transport, and maintain constant speed throughout the dive. Using biologging sensors, we show that oceanic whitetip shark ( Carcharhinus longimanus ) behavior matches these predictions. We estimate that daily energy requirements of an adult shark can be met by consuming approximately 1–1.5 kg of prey (1.5% body mass) per day; shark-borne video footage shows a shark encountering potential prey numbers exceeding that amount. Oceanic whitetip sharks showed incredible plasticity in their behavioral strategies, ranging from short low-energy bursts on descents, to high-speed vertical surface breaches from considerable depth. Oceanic whitetips live a life of energy speculation with minimization, very different to those of tunas and billfish.