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Alicia H Escalante - One of the best experts on this subject based on the ideXlab platform.

  • How can the feeding habits of the sand Tiger Shark influence the success of conservation programs
    Animal Conservation, 2009
    Co-Authors: Luis O Lucifora, Verónica B. García, Alicia H Escalante
    Abstract:

    The feeding habits of the sand Tiger Shark Carcharias taurus, one of the most threatened Sharks of the world, are poorly known. Sand Tiger Sharks are critically endangered in the South-west Atlantic. Since 2007, the law requires that all individuals caught in recreational fisheries off Argentina must be released. Using data from a north Patagonian recreational fishery (n=164 stomachs with contents), we analyzed the diet of sand Tiger Sharks in relation with size, sex, maturity stage and season; assessed prey consumption patterns and hooking location; and estimated diet overlap with fishery landings. Sand Tiger Sharks consumed mainly teleosts (55.4% of the total prey number, N) and elasmobranchs (41.84%N), and ate more benthic elasmobranchs (batoids and angel Sharks) as they become larger. Sharks swallowed prey mostly in one piece (93.7%) and were hooked mainly in internal organs (87.4%, n=175), causing occlusion and perforation of the esophagus and stomach, and lacerations to the pericardium, heart and liver. Sand Tiger Sharks fed on the most heavily landed species, overlapping almost completely (>90%) with fishery landings. Conservation plans should take into account that releasing hooked Sharks could be insufficient to minimize fishing mortality and that competition for food with fisheries is likely to occur.

  • Tooth row counts, vicariance, and the distribution of the sand Tiger Shark Carcharias taurus
    Ecography, 2003
    Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alberto Luis Cione, Alicia H Escalante
    Abstract:

    Geographic variation in tooth row counts among sand Tiger Sharks Carcharias taurus (Chondrichthyes), from the SW Atlantic, NW Atlantic and the East China Sea is analyzed in this paper. We found significant differences between sand Tigers from the SW Atlantic (Southern Hemisphere population) and each of the other two (Northern Hemisphere) regions in the number of upper lateral tooth rows, and between individuals from the SW Atlantic and the East China Sea in the total number of upper tooth rows. Sand Tiger Sharks from the two Northern Hemisphere populations did not differ in any of the studied variables. Our results agree with comparisons of vertebral counts between sand Tiger Sharks from Southern and Northern Hemispheres. Both lines of evidence suggest that Southern and Northern Hemisphere populations of C. taurus were isolated to a larger extent than populations of the Northern Hemisphere. The fossil record of the genus Carcharias begins in the Early Cretaceous and C. taurus is certainly known since the Late Miocene. During the Miocene, the Tethys Sea separating northern and southern land masses was still present and it provided a continuous temperate shallow sea that could allow dispersal of sand Tiger Sharks along Northern Hemisphere seas. Independent observations on the distribution and evolutionary history of the genera Myripristis, Neoniphon, Sargocentron and Aphanius, and genetic studies on the temperate Shark genus Mustelus that indicate a close relationship between the Indo-Pacific M. manazo and the Mediterranean M. asterias suggest that this hypothesis is plausible and deserves to be tested.

  • analysis of dental insertion angles in the sand Tiger Shark carcharias taurus chondrichthyes lamniformes
    Cybium, 2001
    Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alicia H Escalante
    Abstract:

    Differences in insertion angles of each tooth type of Carcharias taurus are described and analyzed within a functional framework. Upper anterior teeth show a more pronounced inward inclination than upper lateral and lower anterior ones that would be related to initial puncturing of prey. Lower ante- rior teeth have an outward inclination, probably related to a function of initial prey grasping by these teeth while the upper anteriors puncture prey. The upper lateral teeth are more inclined than the lower lateral. Upper and lower lateral teeth would be adapted to hold prey. A ventral inclination of the anterior part of the palatoquadrate is present in C.!taurus, and it is likely to facilitate the puncturing work of the upper anterior and to enhance the patchiness of these teeth. We also report some dental anomalies such as inter- mediate tooth reversal, reduced first and second lower anterior teeth, presence of hook-like anterior and lateral teeth, and the absence of a lower lateral tooth. These latter two anomalies are described for the first time in C.!taurus. Our results agree with previously published interpretations based on tooth shape. The results here presented can be considered as a working hypothesis for future experimental research.

Bonnie J Holmes - One of the best experts on this subject based on the ideXlab platform.

  • genetic population structure and demography of an apex predator the Tiger Shark galeocerdo cuvier
    Ecology and Evolution, 2019
    Co-Authors: Agathe Pirog, Sébastien Jaquemet, Bonnie J Holmes, Virginie Ravigne, Geremy Cliff, Eric Clua, Nigel E Hussey, John E G Nevill, Andrew J Temple, Per Berggren
    Abstract:

    Population genetics has been increasingly applied to study large Sharks over the last decade. Whilst large Shark species are often difficult to study with direct methods, improved knowledge is needed for both population management and conservation, especially for species vulnerable to anthropogenic and climatic impacts. The Tiger Shark, Galeocerdo cuvier, is an apex predator known to play important direct and indirect roles in tropical and subtropical marine ecosystems. While the global and Indo‐West Pacific population genetic structure of this species has recently been investigated, questions remain over population structure and demographic history within the western Indian (WIO) and within the western Pacific Oceans (WPO). To address the knowledge gap in Tiger Shark regional population structures, the genetic diversity of 286 individuals sampled in seven localities was investigated using 27 microsatellite loci and three mitochondrial genes (CR, COI, and cytb). A weak genetic differentiation was observed between the WIO and the WPO, suggesting high genetic connectivity. This result agrees with previous studies and highlights the importance of the pelagic behavior of this species to ensure gene flow. Using approximate Bayesian computation to couple information from both nuclear and mitochondrial markers, evidence of a recent bottleneck in the Holocene (2,000–3,000 years ago) was found, which is the most probable cause for the low genetic diversity observed. A contemporary effective population size as low as 111 [43,369] was estimated during the bottleneck. Together, these results indicate low genetic diversity that may reflect a vulnerable population sensitive to regional pressures. Conservation measures are thus needed to protect a species that is classified as Near Threatened.

  • a perspective on future Tiger Shark research
    Frontiers in Marine Science, 2019
    Co-Authors: Kim N Holland, James M Anderson, Daniel M Coffey, Bonnie J Holmes, Carl G Meyer, Mark A Royer
    Abstract:

    This ‘Perspectives’ paper identifies aspects of Tiger Shark (Galeocerdo cuvier) biology that are currently unknown or for which additional data are needed to improve interpretive power. Some of these data gaps may be regional. Technical or methodological approaches to acquiring these data are suggested. Some of these technologies already exist, some are in development and some exist in concept only. Reproductive biology and behavior, social interactions and the behavioral ecology of sub-adults are among the areas identified as deserving of future research effort

  • lack of multiple paternity in the oceanodromous Tiger Shark galeocerdo cuvier
    Royal Society Open Science, 2018
    Co-Authors: Bonnie J Holmes, M. B. Bennett, Ian R Tibbetts, Lisa C Pope, Samuel M Williams, J. R. Ovenden
    Abstract:

    Multiple paternity has been documented as a reproductive strategy in both viviparous and ovoviviparous elasmobranchs, leading to the assumption that multiple mating may be ubiquitous in these fishes. However, with the majority of studies conducted on coastal and nearshore elasmobranchs that often form mating aggregations, parallel studies on pelagic, semi-solitary species are lacking. The Tiger Shark (Galeocerdo cuvier) is a large pelagic Shark that has an aplacental viviparous reproductive mode which is unique among the carcharhinids. A total of 112 pups from four pregnant Sharks were genotyped at nine microsatellite loci to assess the possibility of multiple paternity or polyandrous behaviour by female Tiger Sharks. Only a single pup provided evidence of possible multiple paternity, but with only seven of the nine loci amplifying for this individual, results were inconclusive. In summary, it appears that the Tiger Sharks sampled in this study were genetically monogamous. These findings may have implications for the genetic diversity and future sustainability of this population.

  • the trophic role of a large marine predator the Tiger Shark galeocerdo cuvier
    Scientific Reports, 2017
    Co-Authors: Michael R Heithaus, Bonnie J Holmes, Luciana C. Ferreira, Michele Thums, Adam Barnett, Katya G Abrantes, Lara Marcus Zamora, Ashley J Frisch
    Abstract:

    Tiger Sharks were sampled off the western (Ningaloo Reef, Shark Bay) and eastern (the Great Barrier Reef; GBR, Queensland and New South Wales; NSW) coastlines of Australia. Multiple tissues were collected from each Shark to investigate the effects of location, size and sex of Sharks on δ13C and δ15N stable isotopes among these locations. Isotopic composition of Sharks sampled in reef and seagrass habitats (Shark Bay, GBR) reflected seagrass-based food-webs, whereas at Ningaloo Reef analysis revealed a dietary transition between pelagic and seagrass food-webs. In temperate habitats off southern Queensland and NSW coasts, Shark diets relied on pelagic food-webs. Tiger Sharks occupied roles at the top of food-webs at Shark Bay and on the GBR, but not at Ningaloo Reef or off the coast of NSW. Composition of δ13C in tissues was influenced by body size and sex of Sharks, in addition to residency and diet stability. This variability in stable isotopic composition of tissues is likely to be a result of adaptive foraging strategies that allow these Sharks to exploit multiple shelf and offshore habitats. The trophic role of Tiger Sharks is therefore both context- and habitat-dependent, consistent with a generalist, opportunistic diet at the population level.

  • Tiger Shark galeocerdo cuvier movement patterns and habitat use determined by satellite tagging in eastern australian waters
    Marine Biology, 2014
    Co-Authors: Bonnie J Holmes, Ian R Tibbetts, Julian G Pepperell, Shane P Griffiths, Fabrice R A Jaine, M. B. Bennett
    Abstract:

    Partial migration is considered ubiquitous among vertebrates, but little is known about the movements of ocean- odromous apex predators such as Sharks, particularly at their range extents. PAT-Mk10 and SPOT5 electronic tags were used to investigate Tiger Shark (Galeocerdo cuvier) spatial dynamics, site fidelity and habitat use off eastern Australia between April 2007 and May 2013. Of the 18 tags deployed, 15 recorded information on depth and/or temperature, and horizontal movements. Tracking times ranged between four and 408 days, with two recovered pop-up archival tags allow- ing 63 days of high-resolution archived data to be analysed. Overall mean proportions of time-at-depth revealed that G. cuvier spent the majority of time-at-depths of 500 m) occurred mostly

Luis O Lucifora - One of the best experts on this subject based on the ideXlab platform.

  • How can the feeding habits of the sand Tiger Shark influence the success of conservation programs
    Animal Conservation, 2009
    Co-Authors: Luis O Lucifora, Verónica B. García, Alicia H Escalante
    Abstract:

    The feeding habits of the sand Tiger Shark Carcharias taurus, one of the most threatened Sharks of the world, are poorly known. Sand Tiger Sharks are critically endangered in the South-west Atlantic. Since 2007, the law requires that all individuals caught in recreational fisheries off Argentina must be released. Using data from a north Patagonian recreational fishery (n=164 stomachs with contents), we analyzed the diet of sand Tiger Sharks in relation with size, sex, maturity stage and season; assessed prey consumption patterns and hooking location; and estimated diet overlap with fishery landings. Sand Tiger Sharks consumed mainly teleosts (55.4% of the total prey number, N) and elasmobranchs (41.84%N), and ate more benthic elasmobranchs (batoids and angel Sharks) as they become larger. Sharks swallowed prey mostly in one piece (93.7%) and were hooked mainly in internal organs (87.4%, n=175), causing occlusion and perforation of the esophagus and stomach, and lacerations to the pericardium, heart and liver. Sand Tiger Sharks fed on the most heavily landed species, overlapping almost completely (>90%) with fishery landings. Conservation plans should take into account that releasing hooked Sharks could be insufficient to minimize fishing mortality and that competition for food with fisheries is likely to occur.

  • Tooth row counts, vicariance, and the distribution of the sand Tiger Shark Carcharias taurus
    Ecography, 2003
    Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alberto Luis Cione, Alicia H Escalante
    Abstract:

    Geographic variation in tooth row counts among sand Tiger Sharks Carcharias taurus (Chondrichthyes), from the SW Atlantic, NW Atlantic and the East China Sea is analyzed in this paper. We found significant differences between sand Tigers from the SW Atlantic (Southern Hemisphere population) and each of the other two (Northern Hemisphere) regions in the number of upper lateral tooth rows, and between individuals from the SW Atlantic and the East China Sea in the total number of upper tooth rows. Sand Tiger Sharks from the two Northern Hemisphere populations did not differ in any of the studied variables. Our results agree with comparisons of vertebral counts between sand Tiger Sharks from Southern and Northern Hemispheres. Both lines of evidence suggest that Southern and Northern Hemisphere populations of C. taurus were isolated to a larger extent than populations of the Northern Hemisphere. The fossil record of the genus Carcharias begins in the Early Cretaceous and C. taurus is certainly known since the Late Miocene. During the Miocene, the Tethys Sea separating northern and southern land masses was still present and it provided a continuous temperate shallow sea that could allow dispersal of sand Tiger Sharks along Northern Hemisphere seas. Independent observations on the distribution and evolutionary history of the genera Myripristis, Neoniphon, Sargocentron and Aphanius, and genetic studies on the temperate Shark genus Mustelus that indicate a close relationship between the Indo-Pacific M. manazo and the Mediterranean M. asterias suggest that this hypothesis is plausible and deserves to be tested.

  • analysis of dental insertion angles in the sand Tiger Shark carcharias taurus chondrichthyes lamniformes
    Cybium, 2001
    Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alicia H Escalante
    Abstract:

    Differences in insertion angles of each tooth type of Carcharias taurus are described and analyzed within a functional framework. Upper anterior teeth show a more pronounced inward inclination than upper lateral and lower anterior ones that would be related to initial puncturing of prey. Lower ante- rior teeth have an outward inclination, probably related to a function of initial prey grasping by these teeth while the upper anteriors puncture prey. The upper lateral teeth are more inclined than the lower lateral. Upper and lower lateral teeth would be adapted to hold prey. A ventral inclination of the anterior part of the palatoquadrate is present in C.!taurus, and it is likely to facilitate the puncturing work of the upper anterior and to enhance the patchiness of these teeth. We also report some dental anomalies such as inter- mediate tooth reversal, reduced first and second lower anterior teeth, presence of hook-like anterior and lateral teeth, and the absence of a lower lateral tooth. These latter two anomalies are described for the first time in C.!taurus. Our results agree with previously published interpretations based on tooth shape. The results here presented can be considered as a working hypothesis for future experimental research.

Agathe Pirog - One of the best experts on this subject based on the ideXlab platform.

  • New insights into the reproductive biology of the Tiger Shark Galeocerdo cuvier and no detection of polyandry in Reunion Island, western Indian Ocean
    Marine and Freshwater Research, 2020
    Co-Authors: Agathe Pirog, Hélène Magalon, Thomas Poirout, Sébastien Jaquemet
    Abstract:

    The reproductive biology of the Tiger Shark Galeocerdo cuvier remains poorly documented because it is difficult to obtain data on a sufficient number of mature individuals to conduct appropriate analyses and thus to adequately investigate its population biology. In this study, the reproductive traits of 150 individuals caught during a Shark control program in Reunion Island (western Indian Ocean), including five gravid females, were investigated. Specific microsatellite loci were used to investigate the occurrence of polyandry. The total length (TL) of the studied individuals was 130–415cm for males and 175–429cm for females. Sizes at maturity were estimated at 278.5cm for males and 336cm for females. Although the length–weight relationships differed between both sexes (analysis of covariance (ANCOVA): intercept, n=49, F1,45=0.95, P=0.34; slope, n=49, F1,45=8.39, P=0.01), the TL–frequency distributions did not differ significantly. Parturition likely occurs during the warm season, in December–January. No evidence of genetic polyandry was detected, and this supports recently published results. This absence of polyandry in the species likely reflects both a long reproductive cycle and a specific reproductive behaviour related to the oceanic nature of the Tiger Shark. These results are valuable for improving conservation and management plans for this species.

  • genetic population structure and demography of an apex predator the Tiger Shark galeocerdo cuvier
    Ecology and Evolution, 2019
    Co-Authors: Agathe Pirog, Sébastien Jaquemet, Bonnie J Holmes, Virginie Ravigne, Geremy Cliff, Eric Clua, Nigel E Hussey, John E G Nevill, Andrew J Temple, Per Berggren
    Abstract:

    Population genetics has been increasingly applied to study large Sharks over the last decade. Whilst large Shark species are often difficult to study with direct methods, improved knowledge is needed for both population management and conservation, especially for species vulnerable to anthropogenic and climatic impacts. The Tiger Shark, Galeocerdo cuvier, is an apex predator known to play important direct and indirect roles in tropical and subtropical marine ecosystems. While the global and Indo‐West Pacific population genetic structure of this species has recently been investigated, questions remain over population structure and demographic history within the western Indian (WIO) and within the western Pacific Oceans (WPO). To address the knowledge gap in Tiger Shark regional population structures, the genetic diversity of 286 individuals sampled in seven localities was investigated using 27 microsatellite loci and three mitochondrial genes (CR, COI, and cytb). A weak genetic differentiation was observed between the WIO and the WPO, suggesting high genetic connectivity. This result agrees with previous studies and highlights the importance of the pelagic behavior of this species to ensure gene flow. Using approximate Bayesian computation to couple information from both nuclear and mitochondrial markers, evidence of a recent bottleneck in the Holocene (2,000–3,000 years ago) was found, which is the most probable cause for the low genetic diversity observed. A contemporary effective population size as low as 111 [43,369] was estimated during the bottleneck. Together, these results indicate low genetic diversity that may reflect a vulnerable population sensitive to regional pressures. Conservation measures are thus needed to protect a species that is classified as Near Threatened.

  • isolation and characterization of eight microsatellite loci from galeocerdo cuvier Tiger Shark and cross amplification in carcharhinus leucas carcharhinus brevipinna carcharhinus plumbeus and sphyrna lewini
    PeerJ, 2016
    Co-Authors: Agathe Pirog, Antonin Blaison, Sébastien Jaquemet, Marc Soria, Hélène Magalon
    Abstract:

    The Tiger Shark Galeocerdo cuvier (Carcharhinidae) is a large elasmobranch suspected to have, as other apex predators, a keystone function in marine ecosystems and is currently considered Near Threatened (Red list IUCN). Knowledge on its ecology, which is crucial to design proper conservation and management plans, is very scarce. Here we describe the isolation of eight polymorphic microsatellite loci using 454 GS-FLX Titanium pyrosequencing of enriched DNA libraries. Their characteristics were tested on a population of Tiger Shark (n = 101) from Reunion Island (SouthWestern Indian Ocean). All loci were polymorphic with a number of alleles ranging from two to eight. No null alleles were detected and no linkage disequilibrium was detected after Bonferroni correction. Observed and expected heterozygosities ranged from 0.03 to 0.76 and from 0.03 to 0.77, respectively. No locus deviated from Hardy-Weinberg equilibrium and the global F IS of the population was of 0.04 NS. Some of the eight loci developed here successfully cross-amplified in the bull Shark Carcharhinus leucas (one locus), the spinner Shark Carcharhinus brevipinna (four loci), the sandbar Shark Carcharhinus plumbeus (five loci) and the scalloped hammerhead Shark Sphyrna lewini (two loci). We also designed primers to amplify and sequence a mitochondrial marker, the control region. We sequenced 862 bp and found a low genetic diversity, with four polymorphic sites, a haplotype diversity of 0.15 and a nucleotide diversity of 2 × 10 −4 .

  • Isolation and characterization of 20 microsatellite markers from Carcharhinus leucas (bull Shark) and cross-amplification in Galeocerdo cuvier (Tiger Shark), Carcharhinus obscurus (dusky Shark) and Carcharhinus plumbeus (sandbar Shark)
    Conservation Genetics Resources, 2015
    Co-Authors: Agathe Pirog, Antonin Blaison, Sébastien Jaquemet, Marc Soria, Hélène Magalon
    Abstract:

    With the development of genetics methods, it becomes possible to study the population structure and some aspects of the reproductive behaviour of endangered Sharks. Here we describe the isolation of 20 polymorphic microsatellite markers in the bull Shark Carcharhinus leucas (Carcharhinidae) and their characteristics. Two to 10 alleles per locus were detected. Observed and expected heterozygosities ranged from 0.00 to 0.78 and from 0.05 to 0.80, respectively. Four markers showed deviations from Hardy–Weinberg equilibrium; among them, three showed presence of null alleles. No linkage disequilibrium was detected among any of the loci. Moreover, four, 11 and 19 of these 20 markers successfully cross-amplified in the Tiger Shark Galeocerdo cuvier, the sandbar Shark Carcharhinus plumbeus and the dusky Shark Carcharhinus obscurus, respectively.

Sébastien Jaquemet - One of the best experts on this subject based on the ideXlab platform.

  • New insights into the reproductive biology of the Tiger Shark Galeocerdo cuvier and no detection of polyandry in Reunion Island, western Indian Ocean
    Marine and Freshwater Research, 2020
    Co-Authors: Agathe Pirog, Hélène Magalon, Thomas Poirout, Sébastien Jaquemet
    Abstract:

    The reproductive biology of the Tiger Shark Galeocerdo cuvier remains poorly documented because it is difficult to obtain data on a sufficient number of mature individuals to conduct appropriate analyses and thus to adequately investigate its population biology. In this study, the reproductive traits of 150 individuals caught during a Shark control program in Reunion Island (western Indian Ocean), including five gravid females, were investigated. Specific microsatellite loci were used to investigate the occurrence of polyandry. The total length (TL) of the studied individuals was 130–415cm for males and 175–429cm for females. Sizes at maturity were estimated at 278.5cm for males and 336cm for females. Although the length–weight relationships differed between both sexes (analysis of covariance (ANCOVA): intercept, n=49, F1,45=0.95, P=0.34; slope, n=49, F1,45=8.39, P=0.01), the TL–frequency distributions did not differ significantly. Parturition likely occurs during the warm season, in December–January. No evidence of genetic polyandry was detected, and this supports recently published results. This absence of polyandry in the species likely reflects both a long reproductive cycle and a specific reproductive behaviour related to the oceanic nature of the Tiger Shark. These results are valuable for improving conservation and management plans for this species.

  • genetic population structure and demography of an apex predator the Tiger Shark galeocerdo cuvier
    Ecology and Evolution, 2019
    Co-Authors: Agathe Pirog, Sébastien Jaquemet, Bonnie J Holmes, Virginie Ravigne, Geremy Cliff, Eric Clua, Nigel E Hussey, John E G Nevill, Andrew J Temple, Per Berggren
    Abstract:

    Population genetics has been increasingly applied to study large Sharks over the last decade. Whilst large Shark species are often difficult to study with direct methods, improved knowledge is needed for both population management and conservation, especially for species vulnerable to anthropogenic and climatic impacts. The Tiger Shark, Galeocerdo cuvier, is an apex predator known to play important direct and indirect roles in tropical and subtropical marine ecosystems. While the global and Indo‐West Pacific population genetic structure of this species has recently been investigated, questions remain over population structure and demographic history within the western Indian (WIO) and within the western Pacific Oceans (WPO). To address the knowledge gap in Tiger Shark regional population structures, the genetic diversity of 286 individuals sampled in seven localities was investigated using 27 microsatellite loci and three mitochondrial genes (CR, COI, and cytb). A weak genetic differentiation was observed between the WIO and the WPO, suggesting high genetic connectivity. This result agrees with previous studies and highlights the importance of the pelagic behavior of this species to ensure gene flow. Using approximate Bayesian computation to couple information from both nuclear and mitochondrial markers, evidence of a recent bottleneck in the Holocene (2,000–3,000 years ago) was found, which is the most probable cause for the low genetic diversity observed. A contemporary effective population size as low as 111 [43,369] was estimated during the bottleneck. Together, these results indicate low genetic diversity that may reflect a vulnerable population sensitive to regional pressures. Conservation measures are thus needed to protect a species that is classified as Near Threatened.

  • isolation and characterization of eight microsatellite loci from galeocerdo cuvier Tiger Shark and cross amplification in carcharhinus leucas carcharhinus brevipinna carcharhinus plumbeus and sphyrna lewini
    PeerJ, 2016
    Co-Authors: Agathe Pirog, Antonin Blaison, Sébastien Jaquemet, Marc Soria, Hélène Magalon
    Abstract:

    The Tiger Shark Galeocerdo cuvier (Carcharhinidae) is a large elasmobranch suspected to have, as other apex predators, a keystone function in marine ecosystems and is currently considered Near Threatened (Red list IUCN). Knowledge on its ecology, which is crucial to design proper conservation and management plans, is very scarce. Here we describe the isolation of eight polymorphic microsatellite loci using 454 GS-FLX Titanium pyrosequencing of enriched DNA libraries. Their characteristics were tested on a population of Tiger Shark (n = 101) from Reunion Island (SouthWestern Indian Ocean). All loci were polymorphic with a number of alleles ranging from two to eight. No null alleles were detected and no linkage disequilibrium was detected after Bonferroni correction. Observed and expected heterozygosities ranged from 0.03 to 0.76 and from 0.03 to 0.77, respectively. No locus deviated from Hardy-Weinberg equilibrium and the global F IS of the population was of 0.04 NS. Some of the eight loci developed here successfully cross-amplified in the bull Shark Carcharhinus leucas (one locus), the spinner Shark Carcharhinus brevipinna (four loci), the sandbar Shark Carcharhinus plumbeus (five loci) and the scalloped hammerhead Shark Sphyrna lewini (two loci). We also designed primers to amplify and sequence a mitochondrial marker, the control region. We sequenced 862 bp and found a low genetic diversity, with four polymorphic sites, a haplotype diversity of 0.15 and a nucleotide diversity of 2 × 10 −4 .

  • Isolation and characterization of 20 microsatellite markers from Carcharhinus leucas (bull Shark) and cross-amplification in Galeocerdo cuvier (Tiger Shark), Carcharhinus obscurus (dusky Shark) and Carcharhinus plumbeus (sandbar Shark)
    Conservation Genetics Resources, 2015
    Co-Authors: Agathe Pirog, Antonin Blaison, Sébastien Jaquemet, Marc Soria, Hélène Magalon
    Abstract:

    With the development of genetics methods, it becomes possible to study the population structure and some aspects of the reproductive behaviour of endangered Sharks. Here we describe the isolation of 20 polymorphic microsatellite markers in the bull Shark Carcharhinus leucas (Carcharhinidae) and their characteristics. Two to 10 alleles per locus were detected. Observed and expected heterozygosities ranged from 0.00 to 0.78 and from 0.05 to 0.80, respectively. Four markers showed deviations from Hardy–Weinberg equilibrium; among them, three showed presence of null alleles. No linkage disequilibrium was detected among any of the loci. Moreover, four, 11 and 19 of these 20 markers successfully cross-amplified in the Tiger Shark Galeocerdo cuvier, the sandbar Shark Carcharhinus plumbeus and the dusky Shark Carcharhinus obscurus, respectively.

  • First Observation of a Pregnant Tiger Shark (Galeocerdo cuvier) at Reunion Island, Western Indian Ocean
    Western Indian Ocean Journal of Marine Science, 2012
    Co-Authors: Sébastien Jaquemet, Antonin Blaison, Malcom Smale, David Guyomard, Marc Soria
    Abstract:

    The Tiger Shark Galeocerdo cuvier is a common predator in tropical oceans although its biology is still not well documented, especially in the western Indian Ocean. We report the first observation of a pregnant Tiger Shark captured at Reunion Island in November 2012. A total of 42 embryos without external yolksacs, measuring 750-846 mm in total length, were found in the two uteri. The sex ratio was nearly 1:1 and males and females did not differ in size or weight. Although the embryos were fully formed, the teeth had not yet erupted through the gums, suggesting that birth would take place a few weeks later. This information is in agreement with observations made in other locations, including the limited data available for this region, suggesting that mating occurs in late winter and parturition in summer