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Alicia H Escalante - One of the best experts on this subject based on the ideXlab platform.
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How can the feeding habits of the Sand Tiger Shark influence the success of conservation programs
Animal Conservation, 2009Co-Authors: Luis O Lucifora, Verónica B. García, Alicia H EscalanteAbstract: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.
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Tooth row counts, vicariance, and the distribution of the Sand Tiger Shark Carcharias taurus
Ecography, 2003Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alberto Luis Cione, Alicia H EscalanteAbstract: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.
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Reproductive ecology and abundance of the Sand Tiger Shark, Carcharias taurus, from the southwestern Atlantic
ICES Journal of Marine Science, 2002Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alicia H EscalanteAbstract:This study analyses the sexual activity and segregation of Sand Tiger Sharks, Carcharias taurus, from Anegada Bay (Argentina). Reproduction-linked movements along the South American Atlantic coast were inferred from data from several SW Atlantic localities. Male Sand Tigers (n=162) matured at 193 cm total length (L T ). Females (n=77) matured between 218 and 235 cm L T . These figures are similar to those from other populations, although size-at-maturity of males was slightly different from South African and Australian populations. In females, the size of ovarian follicles was positively correlated with gonadosomatic index and negatively correlated with hepatosomatic index, while the liver was significantly larger than in males. Sand Tiger Sharks were present in Anegada Bay from December to April. Males were significantly more abundant than females (2:1). Significant differences in reproductive condition through time were observed in males. During January and February males had seminal vesicles full of spermatozeugmata but by March and April the vesicles were empty. As the proportion of males with a lighter colouration peaked from January to March, it is very likely that mating takes place during January and February. The skewed sex-ratio during the mating season indicates a possible strong competition for mates among males, as observed in captivity. Males, females and some juveniles occur in Argentinean and Uruguayan waters, where mating takes place. Pregnant females occur in subtropical waters of southern Brazil, where they give birth. Given that pregnant and non-pregnant females occur at the same time in different zones, we suggest that the female reproductive cycle is biennial. Striking differences among migratory patterns of Sand Tiger Sharks from the SW and NW Atlantic and South Africa were observed. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.
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analysis of dental insertion angles in the Sand Tiger Shark carcharias taurus chondrichthyes lamniformes
Cybium, 2001Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alicia H EscalanteAbstract: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.
Ilze K. Berzins - One of the best experts on this subject based on the ideXlab platform.
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Correlations of Swimming Patterns with Spinal Deformities in the Sand Tiger Shark, Carcharias taurus
International Journal of Comparative Psychology, 2013Co-Authors: Erin E. Tate, Paul A. Anderson, Daniel R. Huber, Ilze K. BerzinsAbstract:Spinal deformities among captive Sand Tiger Sharks, Carcharias taurus, are unfortunately common, and abnormal swimming behavior due to constrained aquarium space has been hypothesized to contribute to the development of this condition. Public aquaria across the United States were surveyed for number, condition (healthy vs. affected), and total length of resident C. taurus specimens and for dimensions of their aquaria. They were also asked to record 10 minute video segments of individual C. taurus swimming in lateral view. Total length of Sharks, regardless of condition, averaged 225 ± 5 (mean ± SE) cm. Aquarium shapes varied widely, but aquaria held median volumes of 1.03 X 106 L, and were a median of 4.6 m in depth and 20.7 m in greatest horizontal distance. The greatest horizontal distance of aquaria was negatively correlated with disease prevalence of resident populations in a logarithmic fashion (r = 0.72). Behaviorally, Sharks were assessed for total time and percentage of time spent swimming in a specific direction (clockwise, counter-clockwise, or linear), in a glide, and tail-beat duration. Regardless of condition, C. taurus spent a median of 98.9% of time swimming and 0.62% of time gliding. Healthy Sharks spent a median of 0.67% gliding versus a median of 0% for afflicted Sharks (p= 0.036), suggesting an increased swim-to-glide ratio among the latter group. All Sharks swam asymmetrically in either a clockwise or counter-clockwise direction for a median of 99.7% of observed time. Affected specimens had tail beat durations of 3.37 ± 0.23 s vs. 2.72 ± 0.10 s for healthy Sharks (p = 0.005). The increase in swim-to-glide ratios and inordinate time spent swimming asymmetrically for all affected Sharks support the hypothesis that swimming patterns induced by captive exhibits may contribute to spinal deformities in C. taurus due to more stress placed on the spine. Large, complex aquarium designs are recommended in the planning of new exhibits to discourage stereotypical swimming behavior and also to provide sufficient length for Sharks to complete natural swimming repertoires. Comprehensive behavioral enrichment activities that encourage complex movement are also recommended as well as considerations such as even weight distribution of the animal during capture, sourcing of appropriately aged Sharks, and nutritional supplementation.
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Mechanical properties of Sand Tiger Shark ( Carcharias taurus ) vertebrae in relation to spinal deformity
Journal of Experimental Biology, 2013Co-Authors: Daniel R. Huber, Paul A. Anderson, Danielle E. Neveu, Charlotte M. Stinson, Ilze K. BerzinsAbstract:SUMMARY Approximately 35% of Sand Tiger Sharks ( Carcharias taurus ) in public aquaria exhibit spinal deformities ranging from compressed vertebrae and loss of intervertebral space to dislocated spines with vertebral degeneration and massive spondylosis caused by excessive mineralization both within vertebrae and outside the notochordal sheath. To identify the mechanical basis of these deformities, vertebral centra from affected ( N =12) and non-affected ( N =9) C. taurus were subjected to axial compression tests on an MTS 858 Bionix material testing system, after which mineral content was determined. Vertebral centra from affected Sharks had significantly lower mineral content and material behavior in nearly all variables characterizing elasticity, plasticity and failure. These mechanical deficiencies are correlated with size at capture, capture method, vitamin C and zinc deficiency, aquarium size and swimming behavior in public aquaria. Non-affected C. taurus had greater stiffness and toughness even though these properties are generally incompatible in mineralized structures, suggesting that the biphasic (mineralized, unmineralized phases) nature of chondrichthyan vertebrae yields material behavior not otherwise observed in vertebrate skeletons. However, vertebral centra from non-affected Sharks had lower mineral content (33%), stiffness (167 MPa), yield strain (14%) and ultimate strength (16 MPa) than other species of Sharks and bony vertebrates, indicating that biomechanical precautions must be taken in the husbandry of this species.
Jürgen Kriwet - One of the best experts on this subject based on the ideXlab platform.
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Probing the ecology and climate of the Eocene Southern Ocean with Sand Tiger Sharks Striatolamia macrota
Paleoceanography and Paleoclimatology, 2020Co-Authors: Sora L. Kim, Thomas Mors, Jürgen Kriwet, Sarah S. Zeichner, Albert S. Colman, Howie D Scher, Matthew HuberAbstract:Many explanations for Eocene climate change focus on the Southern Ocean – where tectonics influenced oceanic gateways, ocean circulation reduced heat transport, and greenhouse gas declines prompted glaciation. To date, few studies focus on marine vertebrates at high latitudes to discern paleoecological and paleoenvironmental impacts of this climate transition. The Tertiary Eocene La Meseta (TELM) Formation has a rich fossil assemblage to characterize these impacts; Striatolamia macrota, an extinct (†) Sand Tiger Shark, is abundant throughout the La Meseta Formation. Body size is often tracked to characterize and integrate across multiple ecological dimensions. †Striatolamia macrota body size distributions indicate limited changes during TELMs 2 – 5 based on anterior tooth crown height (n = 450, mean = 19.6 ± 6.4mm). Similarly, environmental conditions remained stable through this period based on δ¹⁸O_(PO4) values from tooth enameloid (n = 42; 21.5 ± 1.6‰), which corresponds to a mean temperature of 22.0 ± 4.0°C. Our preliminary e_(Nd) (n = 4) results indicate an early Drake Passage opening with Pacific inputs during TELM 2 – 3 (45 – 43 Ma) based on single unit variation with an overall radiogenic trend. Two possible hypotheses to explain these observations are (1) †S. macrota modified its migration behavior to ameliorate environmental changes related to the Drake Passage opening, or (2) the local climate change was small and gateway opening had little impact. While we cannot rule out an ecological explanation, a comparison with climate model results suggests that increased [CO₂] produces warm conditions that also parsimoniously explain the observations.
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the southernmost occurrence of brachycarcharias lamniformes odontaspididae from the eocene of antarctica provides new information about the paleobiogeography and paleobiology of paleogene Sand Tiger Sharks
Rivista Italiana Di Paleontologia E Stratigrafia, 2018Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Thomas Mors, Marcelo Reguero, Jürgen KriwetAbstract:The first record of one of the most common and widespread Paleogene selachians, the Sand Tiger Shark Brachycarcharias , in the Ypresian strata of the La Meseta Formation, Seymour Island, Antarctica, is provided herein. Selachians from the early Eocene horizons of this deposit represent the southernmost Paleogene occurrences in the fossil record, and are represented by isolated teeth belonging to orectolobiforms, lamniforms, carcharhiniforms, squatiniforms and pristiophoriforms. The combination of dental characters of the 49 isolated teeth collected from the horizons TELMs 2, 4 and 5 supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a lamniform species widely spread across the Northern Hemisphere during the early Paleogene. The unambiguous first report of this lamniform Shark in the Southern Hemisphere in the Eocene of the La Meseta Formation improves our knowledge concerning the diversity and paleobiology of the cartilaginous fishes of this deposit, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine settings after the end-Cretaceous extinction and before the establishment of the modern marine ecosystems.
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Eocene Sand Tiger Sharks (Lamniformes, Odontaspididae) from the Bolca Konservat-Lagerstätte, Italy: palaeobiology, palaeobiogeography and evolutionary significance
Historical Biology, 2017Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Giorgio Carnevale, Jürgen KriwetAbstract:AbstractHere we report the first record of one of the most common and widespread Palaeogene selachians, the Sand Tiger Shark Brachycarcharias, from the Ypresian Bolca Konservat-Lagerstatte. The combination of dental character of the 15 isolated teeth collected from the Pesciara and Monte Postale sites (e.g. anterior teeth up to 25 mm with fairly low triangular cusp decreasing regularly in width; one to two pairs of well-developed lateral cusplets; root with broadly separated lobes; upper teeth with a cusp bent distally) supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a species widely spread across the North Hemisphere during the early Palaeogene. The unambiguous first report of this lamniform Shark in the Eocene Bolca Konservat-Lagerstatte improves our knowledge concerning the diversity and palaeobiology of the cartilaginous fishes of this palaeontological site, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine ...
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Eocene Sand Tiger Sharks (Lamniformes, Odontaspididae) from the Bolca Konservat-Lagerstätte, Italy: palaeobiology, palaeobiogeography and evolutionary significance
2017Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Giorgio Carnevale, Jürgen KriwetAbstract:Here we report the first record of one of the most common and widespread Palaeogene selachians, the Sand Tiger Shark Brachycarcharias, from the Ypresian Bolca Konservat-Lagerstätte. The combination of dental character of the 15 isolated teeth collected from the Pesciara and Monte Postale sites (e.g. anterior teeth up to 25 mm with fairly low triangular cusp decreasing regularly in width; one to two pairs of well-developed lateral cusplets; root with broadly separated lobes; upper teeth with a cusp bent distally) supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a species widely spread across the North Hemisphere during the early Palaeogene. The unambiguous first report of this lamniform Shark in the Eocene Bolca Konservat-Lagerstätte improves our knowledge concerning the diversity and palaeobiology of the cartilaginous fishes of this palaeontological site, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine settings after the end-Cretaceous extinction.
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biology and dental morphology ofpriscusurus adruptodontus gen et sp nov chondrichthyes lamniformes from the albian early cretaceous of peru
Journal of Vertebrate Paleontology, 2006Co-Authors: Jürgen KriwetAbstract:Abstract A partial association of fourteen teeth from a small lamniform Shark with uncertain affinities is described. The material comes from the middle? Albian of Peru and represents a new genus and species, Priscusurus adruptodontus. The new taxon is characterized by a tearing-type dentition with comparably small teeth that lack any ornamentation and lateral cusplets. Other diagnostic features include distally inclined cusps in all tooth positions, an asymmetric root, and the lack of a lingual nutritive groove. The most remarkable feature is the very distinctly shaped lingual tooth neck, which differentiates teeth of the new taxon from all known lamniforms. The total body length, which was estimated from the crown height of the tallest preserved anterior tooth and a regression equation for the dentition of the modern Sand Tiger Shark, Carcharias taurus, is only 69 cm. The very rare finds of this taxon and the restricted occurrence may indicate that Priscusurus was probably an endemic element of the shel...
Luis O Lucifora - One of the best experts on this subject based on the ideXlab platform.
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How can the feeding habits of the Sand Tiger Shark influence the success of conservation programs
Animal Conservation, 2009Co-Authors: Luis O Lucifora, Verónica B. García, Alicia H EscalanteAbstract: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.
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Tooth row counts, vicariance, and the distribution of the Sand Tiger Shark Carcharias taurus
Ecography, 2003Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alberto Luis Cione, Alicia H EscalanteAbstract: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.
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Reproductive ecology and abundance of the Sand Tiger Shark, Carcharias taurus, from the southwestern Atlantic
ICES Journal of Marine Science, 2002Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alicia H EscalanteAbstract:This study analyses the sexual activity and segregation of Sand Tiger Sharks, Carcharias taurus, from Anegada Bay (Argentina). Reproduction-linked movements along the South American Atlantic coast were inferred from data from several SW Atlantic localities. Male Sand Tigers (n=162) matured at 193 cm total length (L T ). Females (n=77) matured between 218 and 235 cm L T . These figures are similar to those from other populations, although size-at-maturity of males was slightly different from South African and Australian populations. In females, the size of ovarian follicles was positively correlated with gonadosomatic index and negatively correlated with hepatosomatic index, while the liver was significantly larger than in males. Sand Tiger Sharks were present in Anegada Bay from December to April. Males were significantly more abundant than females (2:1). Significant differences in reproductive condition through time were observed in males. During January and February males had seminal vesicles full of spermatozeugmata but by March and April the vesicles were empty. As the proportion of males with a lighter colouration peaked from January to March, it is very likely that mating takes place during January and February. The skewed sex-ratio during the mating season indicates a possible strong competition for mates among males, as observed in captivity. Males, females and some juveniles occur in Argentinean and Uruguayan waters, where mating takes place. Pregnant females occur in subtropical waters of southern Brazil, where they give birth. Given that pregnant and non-pregnant females occur at the same time in different zones, we suggest that the female reproductive cycle is biennial. Striking differences among migratory patterns of Sand Tiger Sharks from the SW and NW Atlantic and South Africa were observed. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.
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analysis of dental insertion angles in the Sand Tiger Shark carcharias taurus chondrichthyes lamniformes
Cybium, 2001Co-Authors: Luis O Lucifora, Roberto Carlos Menni, Alicia H EscalanteAbstract: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.
Tonya M. Clauss - One of the best experts on this subject based on the ideXlab platform.
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Natural environmental conditions and collaborative efforts provide the secret to success for Sand Tiger Shark Carcharias taurus reproduction in aquaria.
Zoo biology, 2020Co-Authors: Jennifer T Wyffels, Kevin A Feldheim, Robert George, Tonya M. Clauss, Chris Coco, Chris Schreiber, Daniel Palmer, Frank Bulman, Craig Pelton, Tim HandselAbstract:Sand Tiger Sharks are an iconic large Shark species held in aquaria worldwide. They rarely reproduce under managed care, with only seven aquaria reporting limited and sporadic success. For the first time in the Americas, a full-term young was born in an aquarium. The young was the result of breeding among a group of Sharks purposefully brought together in 2016 for reproduction. Sharks were maintained in natural seawater and exposed to natural light and seasonal temperature fluctuations similar to their in situ counterparts. Decreased food consumption associated with breeding season and gestation was observed. Gestation time estimated from breeding observations and parturition was 321 days. Although the neonate was stillborn, this was a significant achievement. The husbandry details described within will be useful for other aquaria striving to support the reproduction of Sand Tiger Sharks.
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testosterone and semen seasonality for the Sand Tiger Shark carcharias taurus
Biology of Reproduction, 2020Co-Authors: Jennifer T Wyffels, Robert George, Lance Adams, Cayman Adams, Tonya M. Clauss, Alisa L. Newton, Michael W. Hyatt, Christopher Yach, Linda M. PenfoldAbstract:Understanding the fundamental reproductive biology of a species is the first step toward identifying parameters that are critical for reproduction and for the development of assisted reproductive techniques. Ejaculates were collected from aquarium (n = 24) and in situ (n = 34) Sand Tiger Sharks Carcharias taurus. Volume, pH, osmolarity, sperm concentration, motility, status, morphology, and plasma membrane integrity were assessed for each ejaculate. Semen with the highest proportion of motile sperm was collected between April and June for both in situ and aquarium Sand Tiger Sharks indicating a seasonal reproductive cycle. Overall, 17 of 30 semen samples collected from aquarium Sharks from April through June contained motile sperm compared to 29 of 29 of in situ Sharks, demonstrating semen quality differences between aquarium and in situ Sharks. Sperm motility, status, morphology, and plasma membrane integrity were significantly higher (P < 0.05) for in situ compared to aquarium Sand Tiger Sharks. Testosterone was measured by an enzyme immunoassay validated for the species. Testosterone concentration was seasonal for both aquarium and in situ Sharks with highest concentrations measured in spring and lowest in summer. In situ Sharks had higher (P < 0.05) testosterone concentration in spring than aquarium Sharks. This study demonstrated annual reproduction with spring seasonality for male Sand Tiger Sharks through marked seasonal differences in testosterone and semen production. Lower testosterone and poorer semen quality was observed in aquarium Sharks likely contributing to the species' limited reproductive success in aquariums.
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Testosterone and semen seasonality for the Sand Tiger Shark Carcharias taurus
Biology of reproduction, 2019Co-Authors: Jennifer T Wyffels, Robert George, Lance Adams, Cayman Adams, Tonya M. Clauss, Alisa L. Newton, Michael W. Hyatt, Christopher Yach, Linda M. PenfoldAbstract:Understanding the fundamental reproductive biology of a species is the first step toward identifying parameters that are critical for reproduction and for the development of assisted reproductive techniques. Ejaculates were collected from aquarium (n = 24) and in situ (n = 34) Sand Tiger Sharks Carcharias taurus. Volume, pH, osmolarity, sperm concentration, motility, status, morphology, and plasma membrane integrity were assessed for each ejaculate. Semen with the highest proportion of motile sperm was collected between April and June for both in situ and aquarium Sand Tiger Sharks indicating a seasonal reproductive cycle. Overall, 17 of 30 semen samples collected from aquarium Sharks from April through June contained motile sperm compared to 29 of 29 of in situ Sharks, demonstrating semen quality differences between aquarium and in situ Sharks. Sperm motility, status, morphology, and plasma membrane integrity were significantly higher (P
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Implantation and Recovery of Long-Term Archival Transceivers in a Migratory Shark with High Site Fidelity.
PloS one, 2016Co-Authors: Danielle E. Haulsee, Dewayne A. Fox, Tonya M. Clauss, Matthew W. Breece, Matthew J. OliverAbstract:We developed a long-term tagging method that can be used to understand species assemblages and social groupings associated with large marine fishes such as the Sand Tiger Shark Carcharias taurus. We deployed internally implanted archival VEMCO Mobile Transceivers (VMTs; VEMCO Ltd. Nova Scotia, Canada) in 20 adult Sand Tigers, of which two tags were successfully recovered (10%). The recovered VMTs recorded 29,646 and 44,210 detections of telemetered animals respectively. To our knowledge, this is the first study to demonstrate a method for long-term (~ 1 year) archival acoustic transceiver tag implantation, retention, and recovery in a highly migratory marine fish. Results show low presumed mortality (n = 1, 5%), high VMT retention, and that non-lethal recovery after almost a year at liberty can be achieved for archival acoustic transceivers. This method can be applied to study the social interactions and behavioral ecology of large marine fishes.
