Sharks can use their electrosensory system to detect electric fields in their environment. Measurements of their electrosensitivity are often derived by calculating the voltage gradient from a model of the charge distribution for an ideal dipole. This study measures the charge distribution around a dipole in seawater and confirms the close correspondence with the model. From this, it is possibl...

Sharks are top predators in many marine ecosystems and can impact community dynamics, yet many shark populations are undergoing severe declines primarily due to overfishing. Obtaining species-specific knowledge on shark spatial ecology is important to implement adequate management strategies for the effective conservation of these taxa. This is particularly relevant concerning highly-mobile spe...

Zooplankton samples were taken in the presence (n 68) and absence (n = 65) of surface f e e d ~ n g zooplanktlvorous basking sharks Cetorh~nus mavimus off Plymouth, southwest England, from May to mid-August, 1995-96 A prelim~nary study In 1995 showed zooplankton density (g m-3) to be 46% higher in samples taken near feeding sharks Calanoid copepods predominated In all samples but were 84 O,rl m...

Sharks are important exhibit animals in aquariums and zoologic institutions worldwide. Although veterinarians are encountering these species more frequently in these institutions, our knowledge regarding safe restraint and anesthesia is limited. To date there have been only a few anecdotal reports or studies evaluating the effects of tricaine methane sulfonate (MS-222), ketamine hydrochloride, ...

The potential effectiveness of marine protected areas (MPAs) as a conservation tool for large sharks has been questioned due to the limited spatial extent of most MPAs in contrast to the complex life history and high mobility of many sharks. Here we evaluated the movement dynamics of a highly migratory apex predatory shark (tiger shark Galeocerdo cuvier) at the Galapagos Marine Reserve (GMR). U...

Metabolic and activity rates determined from free-ranging juvenile scalloped hammerhead shark pups (Sphyrna lewini) in Kāne’ohe Bay, Ō’ahu, HI, were used to develop a simplified energy budget for this population. Five shark pups were tracked using a specially designed acoustic tail beat transmitter. Previous laboratory experiments determined that tail beat frequency (TBF) and water temperature ...

Tiger sharks (Galeocerdo cuvier) are a wide ranging, potentially keystone predator species that display a variety of horizontal movement patterns, making use of coastal and pelagic waters. Far less, however, is known about their vertical movements and use of the water column. We used pop-up satellite archival tags with two data sampling rates (high rate and standard rate tags) to investigate th...

Because sharks possess an unusual suite of reproductive characteristics, including internal fertilization, sperm storage, relatively low fecundity, and reproductive modes that range from oviparity to viviparity, they can provide important insight into the evolution of mating systems and sexual selection. Yet, to date, few studies have characterized behavioral and genetic mating systems in natur...

1. Sharks are hungry: Sharks like all animals are not hungry all the time (Wetherbee, et al, 2012; Semmens, et al, 2013). Research has also shown that large predatory sharks are extremely adapted to catching their prey and have been found to have a broad range of prey items in their stomach (Wetherbee, et al, 2012; Bruce, et al, 2006; Simpfendorfer, 2001) indicating a varied diet. Large predato...

Overfishing is arguably the greatest ecological threat facing the oceans, yet catches of many highly migratory fishes including oceanic sharks remain largely unregulated with poor monitoring and data reporting. Oceanic shark conservation is hampered by basic knowledge gaps about where sharks aggregate across population ranges and precisely where they overlap with fishers. Using satellite tracki...