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Sand tiger sharks
\"Sand tiger sharks are unique for their jagged teeth and ability to swallow air to help them float underwater. Find out why these slow-moving sharks are not as scary as they look. Download the Capston 4D app to access a variety of bonus content.\"-- Provided by publisher.
Book
Testosterone and semen seasonality for the sand tiger shark Carcharias taurus
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. Summary sentence During mating season, in situ sand tiger sharks Carcharias taurus have higher plasma testosterone and better semen quality than aquarium housed sand tiger sharks impairing reproductive success of aquarium populations.
Journal Article
Sand tiger sharks
Describes the physical characteristics, behavior, and life cycle of sand tiger sharks.
Book
Spatial ecology of Carcharias taurus in the northwestern Mid-Atlantic coastal ocean
The sand tiger shark Carcharias taurus is a highly migratory coastal species with declining populations worldwide. This species exhibits many behaviors that make coastal sharks difficult to manage, including aggregatory behavior, sexual segregation, and large-scale migrations through shallow coastal waters with many opportunities for human interactions. Sand tigers from the Western North Atlantic subpopulation are known to seasonally inhabit Delaware Bay and surrounding coastal waters. This region has been recommended as a habitat area of particular concern for the Western North Atlantic sand tiger population, and increased understanding of their movements and habitat requirements will facilitate management efforts. We developed models to predict sand tiger occupancy using spatially dynamic environmental predictors. Our models predicted sand tiger (juveniles, adult males, adult females, and all sharks combined) occurrences in 2 study regions, the Delaware Bay and the western Mid-Atlantic coastal ocean. Sea surface temperature, day of year, water depth, and remote sensing reflectance at 555 nm were the most important environmental predictors of occurrence, and correctly predicted 80–89% of sand tiger acoustic telemetry records in the 2 study regions. Our models predicted differences in the timing and location of occurrences among juveniles and adults, as well as areas where these life history stages overlap in the Mid-Atlantic coastal ocean. Our hope is that a daily forecast of sand tiger occurrence from our modeling efforts could be useful for conservation and management efforts in this important region, as well as for studying the spatial and behavioral ecology of this important top predator.
Journal Article
Flip & Fin : super sharks to the rescue!
When sand shark twins Flip and Fin try to rescue people and save the day like the heroes of their favorite cartoon, there's a misunderstanding.
Book
Reproductive philopatry in a coastal shark drives age-related population structure
The cosmopolitan lamniform shark Carcharias taurus (commonly known as the ragged-tooth, grey nurse or sand tiger shark) is threatened by overexploitation in parts of its range. Return migrations of females to specific nursery areas suggest that females exhibit reproductive philopatry, a behaviour that over time might lead to genetically isolated subpopulations over various spatial scales. To investigate genetic evidence for reproductive philopatry, genetic data from mitochondrial and microsatellite markers were generated for 104 young-of-the-year and juvenile sharks. Comparing the smallest versus the largest young sharks revealed a pattern of size-related differentiation between nurseries that was only found in the smaller size class. This not only confirms reproductive philopatry of their mothers, but is also in line with previous observations of larger juvenile sharks increasing their migration range and moving between sites. Our results highlight the need to target young-of-the-year sharks when investigating reproductive philopatry to exclude roaming individuals that obscure size-related signals of genetic differentiation. Given the species’ high susceptibility to overexploitation, the evidence for reproductive philopatry is of direct importance to the management and conservation of C. taurus worldwide. As many nursery areas as possible should be protected to ensure that the number of locally resident juveniles and the pool of the returning females remain stable in the long term. This may warrant protected areas, or time-area closures, prohibiting exploitation in the nursery areas during pupping season.
Journal Article
Habitat selection of a coastal shark species estimated from an autonomous underwater vehicle
Quantifying habitat selection in marine organisms is challenging because it is difficult to obtain species location information with multiple corresponding habitat measurements. In the ocean, habitat conditions vary on many spatiotemporal scales, which have important consequences for habitat selection. While macroscale biotic and abiotic features influence seasonal movements (spatial scales of 100–1000 km), selectivity of conditions on mesoscales (1–100 km) reflects an animal’s response to the local environment. In this study, we examined habitat selectivity by pairing acoustic telemetry with environmental habitat parameters measured by an autonomous underwater vehicle (AUV), and demonstrate that migrating sand tiger sharks Carcharias taurus along the East Coast of the USA did not randomly use the coastal environment. Of the variables examined, we found evidence to suggest that sand tigers were selecting their habitat based on distance to shore, salinity, and colored dissolved organic matter (CDOM). Notably, temperature was not predictive of habitat use in our study. We posit that during their coastal migration, sand tigers select for specific mesoscale coastal habitats that may inform navigation or feeding behaviors. To our knowledge, this is the first empirical measure of mesoscale habitat selection by a coastal marine organism using an AUV. The applications of this method extend beyond the habitat selectivity of sand tigers, and will prove useful for future studies combining in situ observations of marine habitats and animal observations.
Journal Article
Hook‐shaped enterolith and secondary cachexia in a free‐living grey nurse shark (Carcharias taurus, Rafinesque 1810)
The carcass of a critically endangered, juvenile female grey nurse shark (Carcharias taurus, Rafinesque 1810) was recovered from a south‐eastern Australian beach and subjected to necropsy. The 1.98‐m‐long shark exhibited advanced cachexia with its total weight (19.0 kg) and liver weight (0.37 kg) reduced by 60% and 89%, respectively, compared with a healthy individual of the same length. Marked tissue decomposition was evident preventing histopathology and identification of a definitive cause of death. At necropsy, the abdominal organs were abnormally displaced and showed marked reductions in size compared with a healthy individual of the same size. Importantly, a hook‐shaped enterolith (HSE), with a rough surface and cream in colour, was found within the spiral valve of the intestine and is to the authors’ knowledge, the first description of such in any marine animal. X‐ray diffractometry showed that the HSE comprised the minerals monohydrocalcite (Ca[CO₃].H₂O; ~70 wt%) and struvite (Mg [NH4] [PO4]. [H2O]6; ~30 wt%). A CT scan showed concentric lamellate concretions around a 7/o offset J‐hook that formed the nidus of the HSE. Nylon fishing line attached to the hook exited the HSE and was evident in the abdominal cavity through a perforation in the intestinal wall where the posterior intestinal artery merges. The most parsimonious reconstruction of events leading to enterolithiasis and secondary cachexia in this shark was the consumption of a hooked fish and subsequent hook migration causing perforations of the cardiac stomach wall followed by the thin, muscular wall of the apposed, sub‐adjacent intestine.
Hook‐shaped enterolith found in the intestine of a stranded, immature female grey nurse shark, Carcharias taurus, that exhibited advanced cachexia. The enterolith was composed of the minerals monohydrocalcite and struvite and a 7/o offset J‐hook formed the nidus. Nylon line attached to the hook (enterolith) was also evident in the abdominal cavity via a perforation of the intestine.
Journal Article
Review of the records of the smalltooth sand tiger shark, Odontaspis ferox (Elasmobranchii: Lamniformes: Odontaspididae), in the Azores
In recent years Azorean fishermen reported the presence of the smalltooth sand tiger shark, Odontaspis ferox (Risso, 1810), a very rare demersal shark species, associated with insular shelves and slopes, with occasional incursions into shallow waters and of poorly known biology and ecology. There are fourteen new records of this species, between 1996 and 2014, captured by spearfishing, harpoons, hand lines, or entangled in fishing gear in the Azores. These records were analysed and complemented with fishermen interviews, providing new locations and new biological data for this species. Also, specimens photographs were studied and post-mortem analysis were carefully carried out in one individual. This species is rare and captured only as bycatch in shallow waters. More detailed information on this species is critically needed in order to assess its conservation status and implement management guidelines. Bycatch statistics are crucial in this respect.
Journal Article