Directed conservation of the world's reef sharks and rays.

Many shark populations are in decline around the world, with severe ecological and economic consequences. Fisheries management and marine protected areas (MPAs) have both been heralded as solutions. However, the effectiveness of MPAs alone is questionable, particularly for globally threatened sharks and rays ('elasmobranchs'), with little known about how fisheries management and MPAs interact to conserve these species.

Tissue metal concentrations and antioxidant enzyme activity in western north Atlantic white sharks (Carcharodon carcharias).

Anthropogenic practices have increased metal contamination in marine ecosystems. Most sharks have long lifespans, occupy an important ecological position at the top of marine food webs, and can accumulate metals. However, reference levels of metal contaminants in the tissues of sharks, particularly, apex predators such as the white shark (Carcharodon carcharias), are lacking.

Widespread diversity deficits of coral reef sharks and rays.

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages.

Diving into the vertical dimension of elasmobranch movement ecology.

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species.

Global collision-risk hotspots of marine traffic and the world's largest fish, the whale shark.

Marine traffic is increasing globally yet collisions with endangered megafauna such as whales, sea turtles, and planktivorous sharks go largely undetected or unreported. Collisions leading to mortality can have population-level consequences for endangered species. Hence, identifying simultaneous space use of megafauna and shipping throughout ranges may reveal as-yet-unknown spatial targets requiring conservation.

Microbiome structure in large pelagic sharks with distinct feeding ecologies.

Background: Sharks play essential roles in ocean food webs and human culture, but also face population declines worldwide due to human activity. The relationship between sharks and the microbes on and in the shark body is unclear, despite research on other animals showing the microbiome as intertwined with host physiology, immunity, and ecology. Research on shark-microbe interactions faces the significant challenge of sampling the largest and most elusive shark species.

Elasmobranch microbiomes: emerging patterns and implications for host health and ecology.

Elasmobranchs (sharks, skates and rays) are of broad ecological, economic, and societal value. These globally important fishes are experiencing sharp population declines as a result of human activity in the oceans. Research to understand elasmobranch ecology and conservation is critical and has now begun to explore the role of body-associated microbiomes in shaping elasmobranch health.

Connecting post-release mortality to the physiological stress response of large coastal sharks in a commercial longline fishery.

Bycatch mortality is a major factor contributing to shark population declines. Post-release mortality (PRM) is particularly difficult to quantify, limiting the accuracy of stock assessments. We paired blood-stress physiology with animal-borne accelerometers to quantify PRM rates of sharks caught in a commercial bottom longline fishery.

First insights into the vertical habitat use of the whitespotted eagle ray Aetobatus narinari revealed by pop-up satellite archival tags.

The whitespotted eagle ray Aetobatus narinari is a tropical to warm-temperate benthopelagic batoid that ranges widely throughout the western Atlantic Ocean. Despite conservation concerns for the species, its vertical habitat use and diving behaviour remain unknown. Patterns and drivers in the depth distribution of A.

Author Correction: Global status and conservation potential of reef sharks.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Global status and conservation potential of reef sharks.

Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally.

Global spatial risk assessment of sharks under the footprint of fisheries.

Effective ocean management and the conservation of highly migratory species depend on resolving the overlap between animal movements and distributions, and fishing effort. However, this information is lacking at a global scale. Here we show, using a big-data approach that combines satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries.

Experimental study of laminar and turbulent boundary layer separation control of shark skin.

The Shortfin Mako shark (Isurus oxyrinchus) is a fast swimmer and has incredible turning agility, and has flexible scales known to bristle up to 50° in the flank regions. It is purported that this bristling capability of the scales may result in a unique pass flow control method to control flow separation and reduce drag. It appears that the scales have evolved to be only actuated when the flow over the body is reversed; thereby inducing a method of inhibiting flow reversal close to the surface.

Correlations of metabolic rate and body acceleration in three species of coastal sharks under contrasting temperature regimes.

The ability to produce estimates of the metabolic rate of free-ranging animals is fundamental to the study of their ecology. However, measuring the energy expenditure of animals in the field has proved difficult, especially for aquatic taxa. Accelerometry presents a means of translating metabolic rates measured in the laboratory to individuals studied in the field, pending appropriate laboratory calibrations.

Modulation of shark prey capture kinematics in response to sensory deprivation.

The ability of predators to modulate prey capture in response to the size, location, and behavior of prey is critical to successful feeding on a variety of prey types. Modulating in response to changes in sensory information may be critical to successful foraging in a variety of environments. Three shark species with different feeding morphologies and behaviors were filmed using high-speed videography while capturing live prey: the ram-feeding blacktip shark, the ram-biting bonnethead, and the suction-feeding nurse shark.

Vertical Movements and Patterns in Diving Behavior of Whale Sharks as Revealed by Pop-Up Satellite Tags in the Eastern Gulf of Mexico.

The whale shark (Rhincodon typus) is a wide-ranging, filter-feeding species typically observed at or near the surface. This shark's sub-surface habits and behaviors have only begun to be revealed in recent years through the use of archival and satellite tagging technology. We attached pop-up satellite archival transmitting tags to 35 whale sharks in the southeastern Gulf of Mexico off the Yucatan Peninsula from 2003-2012 and three tags to whale sharks in the northeastern Gulf off Florida in 2010, to examine these sharks' long-term movement patterns and gain insight into the underlying factors influencing their vertical habitat selection.

Smells Like Home: The Role of Olfactory Cues in the Homing Behavior of Blacktip Sharks, Carcharhinus limbatus.

Animal navigation in the marine environment is believed to be guided by different sensory cues over different spatial scales. Geomagnetic cues are thought to guide long-range navigation, while visual or olfactory cues allow animals to pinpoint precise locations, but the complete behavioral sequence is not yet understood. Terra Ceia Bay is a primary nursery area for blacktip sharks, Carcharhinus limbatus, on southwestern Florida's Gulf of Mexico coast.

Population Structure and Seasonal Migration of the Spotted Eagle Ray, Aetobatus narinari.

Few studies have reported on the fine-scale population genetics of batoid species in the Atlantic basin. Here, we investigate the genetic diversity and population structure of the spotted eagle ray, Aetobatus narinari, sampled in the northeastern and southwestern parts of the Gulf of Mexico and in the northwestern Caribbean Sea. Samples were collected from 286 individuals sampled across 3 geographic localities.

Constructional morphology within the head of hammerhead sharks (sphyrnidae).

The study of functional trade-offs is important if a structure, such as the cranium, serves multiple biological roles, and is, therefore, shaped by multiple selective pressures. The sphyrnid cephalofoil presents an excellent model for investigating potential trade-offs among sensory, neural, and feeding structures. In this study, hammerhead shark species were chosen to represent differences in head form through phylogeny.

There and back again: a review of residency and return migrations in sharks, with implications for population structure and management.

The overexploitation of sharks has become a global environmental issue in need of a comprehensive and multifaceted management response. Tracking studies are beginning to elucidate how shark movements shape the internal dynamics and structure of populations, which determine the most appropriate scale of these management efforts. Tracked sharks frequently either remain in a restricted geographic area for an extended period of time (residency) or return to a previously resided-in area after making long-distance movements (site fidelity).

Movable shark scales act as a passive dynamic micro-roughness to control flow separation.

Shark scales on fast-swimming sharks have been shown to be movable to angles in excess of 50°, and we hypothesize that this characteristic gives this shark skin a preferred flow direction. During the onset of separation, flow reversal is initiated close to the surface. However, the movable scales would be actuated by the reversed flow thereby causing a greater resistance to any further flow reversal and this mechanism would disrupt the process leading to eventual flow separation.

Multisensory integration and behavioral plasticity in sharks from different ecological niches.

The underwater sensory world and the sensory systems of aquatic animals have become better understood in recent decades, but typically have been studied one sense at a time. A comprehensive analysis of multisensory interactions during complex behavioral tasks has remained a subject of discussion without experimental evidence. We set out to generate a general model of multisensory information extraction by aquatic animals.