One hundred seventeen specimens of sharks were caught along the coast of Pernambuco State, Northern Brazil, between May 2004 and May 2007, among which 86 were blacknose sharks, Carcharhinus acronotus, enabling a more detailed study of the species. Blacknose sharks were caught in the 2 study areas along the Boa Viagem/Piedade and Paiva beaches, accounting for the highest relative abundance among...

White-tip reef sharks are common inhabitants of the shallow waters surrounding the Galapagos Islands, where several known aggregation sites have become touristic attractions. With the aim to describe site fidelity and residency patterns of the white-tip reef sharks in a saltwater creek, we used the ultrasonic telemetry method. The study was undertaken in a saltwater channel South of Academy Bay...

Citizen science is promoted as a simple and cost-effective alternative to traditional approaches for the monitoring of populations of marine megafauna. However, the reliability of datasets collected by these initiatives often remains poorly quantified. We compared datasets of shark counts collected by professional dive guides with acoustic telemetry data from tagged sharks collected at the same...

Eight whale sharks tagged with pop-up satellite archival tags off the Gulf of California, Mexico, were tracked for periods of 14-134 days. Five of these sharks were adults, with four females visually assessed to be pregnant. At least for the periods they were tracked, juveniles remained in the Gulf of California while adults moved offshore into the eastern Pacific Ocean. We propose that parturi...

Wound healing is important for sharks from the earliest life stages, for example, as the 'umbilical scar' in viviparous species heals, and throughout adulthood, when sharks can incur a range of external injuries from natural and anthropogenic sources. Despite anecdotal accounts of rapid healing in elasmobranchs, data regarding recovery and survival of individuals from different wound or injury ...

Bamboo sharks (Chiloscyllium griseum) were tested for their ability to perceive subjective and illusionary contours as well as line length illusions. Individuals were first trained to differentiate between squares, triangles, and rhomboids in a series of two alternative forced-choice experiments. Transfer tests then elucidated whether Kanizsa squares and triangles, grating gaps and phase shifte...

The space utilization and distribution of young (<2 yr old) bull sharks Carcharhinus leucas within a 27 km stretch of the Caloosahatchee River estuary in Southwest Florida was examined using an array of acoustic monitors to define influences of environmental variables. A total of 56 young sharks from 3 cohorts (2003, 2004, 2005) were fitted with acoustic tags and monitored for up to 460 d. Shar...

BACKGROUND Fishermen's knowledge is a source of indispensable information in decision-making processes related to efforts to stimulate the management and conservation of fishing resources, especially in developing countries. This study analyzed the knowledge of fishermen from three municipal areas of Bahia in northeast Brazil regarding the behavior repertoire of sharks and the possible influenc...

Several factors that influence the evolution of the unusual head morphology of hammerhead sharks (family Sphyrnidae) are proposed but few are empirically tested. In this study we tested the 'enhanced binocular field' hypothesis (that proposes enhanced frontal binocularity) by comparison of the visual fields of three hammerhead species: the bonnethead shark, Sphyrna tiburo, the scalloped hammerh...

Sharks play a key role in the structure of marine food webs, but are facing major threats due to overfishing and habitat degradation. Although sharks are also assumed to be at relatively high risk from climate change due to a low intrinsic rate of population growth and slow rates of evolution, ocean acidification (OA) has not, until recently, been considered a direct threat. New studies have be...