Carl G. Meyer

University of Hawai'i System · Hawaii Institute of Marine Biology

The Mistaken Identity Hypothesis (MIH) interprets shark bites on surfers, swimmers and snorkel-ers as 'mistakes' stemming primarily from similarities in the visual appearance of ocean users and the sharks typical prey. MIH is now widely accepted as fact by the general public and some sections of the scientific community despite remaining unproven....

We analyzed a tiger shark (estimated 2.8 m total length) bite on a snorkeler. The removal of the terminal part of the leg suggests a predatory motivation for the bite. This is the first documented bite by a tiger shark in French Polynesia waters for the past 75 years. When sharks bite humans, the removal of large pieces of flesh or bones indicates...

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 globa...

Background - Biologging technologies have yielded new insights into the ecology and behaviour of elasmobranchs, but to date most studies involve animal capture and restraint to attach tags. Capturing animals usually results in a period of atypical behaviour after release and is undesirable or simply not possible for large and vulnerable elasmobranc...

Shark depredation is a worldwide yet not well understood problem that is responsible for economic losses in both commercial and recreational fisheries. We collaborated with fishers from the Mariana Islands in the western Pacific to identify depredating shark species via mitochondrial DNA (mtDNA) barcoding of partially consumed fish from real‐world...

Acoustic telemetry is widely used to investigate aquatic animal movement. Pulse position modulation (PPM) is an acoustic telemetry method that allows multiple unique identification codes to be transmitted at a single acoustic frequency, typically in the 69 kHz range. However, because the potential number of unique identification codes (i.e. tags) i...

Understanding why sharks bite humans is essential for developing strategies to prevent these incidents. Here, we use bite wound characteristics and eye witness descriptions of shark behavior to determine the likely motivation for several bites perpetrated by an oceanic whitetip (OWT) shark Carcharhinus longimanus on an adult female snorkeler off Mo...

Identifying the species involved in shark bite incidents is an ongoing challenge but is important to mitigate risk. We developed a sampling protocol to identify shark species from DNA transferred to inanimate objects during bite incidents. To develop and refine the technique, we swabbed shark bite impressions on surfboards and wetsuit neoprene coll...

Regional endothermy has evolved several times in marine fishes, and two competing hypotheses are generally proposed to explain the evolutionary drivers behind this trait: thermal niche expansion and elevated cruising speeds. Evidence to support either hypothesis is equivocal, and the ecological advantages conferred by endothermy in fishes remain de...

DNA evidence is routinely used to identify individual predators responsible for attacks on people and livestock in terrestrial settings. However, the use of transfer DNA techniques in aquatic environments20 for similar purposes is a recent development. To date, DNA barcoding has been used successfully to identify shark species depredating fish catc...

DNA evidence is routinely used to identify individual predators responsible for attacks on people and livestock in terrestrial settings. However, the transfer of DNA techniques to aquatic environments for similar purposes is a recent development. To date, DNA barcoding has been used successfully to identify shark species depredating fish catches an...

Advances in biologging technology have enabled 3D dead-reckoning reconstruction of marine animal movements at spatiotemporal scales of meters and seconds. Examining high-resolution 3D movements of sharks (Galeocerdo cuvier, N = 4; Rhincodon typus, N = 1), sea turtles (Chelonia mydas, N = 3), penguins (Aptenodytes patagonicus, N = 6), and marine mam...

Selective removal of problem individuals following shark bite incidents would be consistent with current management practices for terrestrial predators, and would be more effective and more environmentally responsible than current mass-culling programs. In parallel, and in addition to traditional forensics analysis, we recommend the routine collect...

Background Great hammerhead sharks (Sphyrna mokarran) routinely swim on their sides and periodically roll from side to side. A previous study used wind tunnel tests with a rigid model hammerhead shark to demonstrate that the rolling behavior could improve swimming efficiency using the tall first dorsal fin as a lift-generating surface. Scalloped ha...

Diel vertical migration is a widespread behavioral phenomenon where organisms migrate through the water column and may modify behavior relative to changing environmental conditions based on physiological tolerances. Here, we combined a novel suite of biologging technologies to examine the thermal physiology (intramuscular temperature), fine-scale s...

We used long-term observations of 55 individually identified tiger sharks (Galeocerdo cuvier) at a shark eco-tourism site off Tahiti to estimate the prevalence, retention times and impacts of residual hooks and trailing line resulting from fisheries interactions. Thirty-eight percent of tiger sharks had at least one fisheries interaction resulting...

This “Perspectives” paper identifies aspects of tiger shark (Galeocerdo cuvier) biology that are currently unknown or for which additional data are needed to improve interpretive power. Some of these data gaps may be regional. Technical or methodological approaches to acquiring these data are suggested. Some of these technologies already exist, som...

Background Globally, there are a large and growing number of researchers using biotelemetry as a tool to study aquatic animals. In Europe, this community lacks a formal network structure. The aim of this study is to review the use of acoustic telemetry in Europe and document the contribution of cross-boundary studies and inter-research group collab...

We compared tiger shark (Galeocerdo cuvier) spatial behaviour among 4 Hawaiian Islands to evaluate whether local patterns of movement could explain higher numbers of shark bites seen around Maui than other islands. Our sample consisted of 96 electronically-tagged (satellite and acoustic transmitters) tiger sharks, individually tracked for up to 6 y...

The redistribution of species has emerged as one of the most pervasive impacts of anthropogenic climate warming, and presents many societal challenges. Understanding how temperature regulates species distributions is particularly important for mobile marine fauna such as sharks given their seemingly rapid responses to warming, and the socio-politic...

The application of genome-wide cytonuclear molecular data to identify management and adaptive units at various spatiotemporal levels is particularly important for overharvested large predatory organisms, often characterized by smaller, localized populations. Despite being “near threatened”, current understanding of habitat use and population struct...

The application of genome-wide cytonuclear molecular data to identify management and adaptive units at various spatio-temporal levels is particularly important for overharvested large predatory organisms, often characterized by smaller, localized populations. Despite being "near threatened", current understanding of habitat use and population struc...

Blooms of alien invasive marine algae have become common, greatly altering the health and stability of nearshore marine ecosystems. Concurrently, herbivorous fishes have been severely overfished in many locations worldwide, contributing to increases in macroalgal cover. We used a multi-pronged, interdisciplinary approach to test if higher biomass o...

In aquatic environments, what one observes during the day can differ substantially by night. The species composition and associated ecological processes that occur during the day are often different than night. In polar seas and at great depths, " night " can span, months, years, and beyond. Teleosts and elasmobranchs have evolved unique sensory an...

The past six decades have seen the emergence of new electronic tag technologies enabling scientists to remotely study the behavior of fishes in a wide variety of aquatic habitats. This revolution began in the 1950s and 1960s with the first studies utilizing acoustic and radio transmitters to actively track fish movements. Subsequent decades saw the...

It has been hypothesized that protecting herbivorous fishes within Marine Reserves (MRs) will help these areas to resist algal overgrowth of corals. However, we lack empirical studies demonstrating the validity of key assumptions underpinning this concept, including that herbivorous fishes (1) are permanently resident within MR boundaries, (2) rout...

Broadly distributed reef fishes tend to have high gene flow mediated by a pelagic larval phase. Here, we survey a reef-associated fish distributed across half the tropical oceans, from the Red Sea to the central Pacific. Our goal is to determine whether genetic structure of the broadly distributed Yellowstripe Goatfish (Mulloidichthys flavolineatus...

We do not expect non air-breathing aquatic animals to exhibit positive buoyancy. Sharks, for example, rely on oil-filled livers instead of gas-filled swim bladders to increase their buoyancy , but are nonetheless ubiquitously regarded as either negatively or neutrally buoyant. Deep-sea sharks have particularly large, oil-filled livers, and are beli...

Marine predators will often perform diel and seasonal movements associated with specific habitats. In tropical areas, mesophotic coral reefs may be an important habitat type for many predators, but their use of these areas has rarely been investigated. We used results of acoustic telemetry and stable isotope analyses to investigate the diel and sea...

Tiger sharks (Galecerdo cuvier) are apex predators characterized by their broad diet, large size and rapid growth. Tiger shark maximum size is typically between 380 & 450 cm Total Length (TL), with a few individuals reaching 550 cm TL, but the maximum size of tiger sharks in Hawaii waters remains uncertain. A previous study suggested tiger sharks g...

Animals are often faced with complex movement decisions, particularly those that involve long-distance dispersal. Partial migrations, ubiquitous among all groups of vertebrates, are a form of long-distance movement that occurs when only some of the animals in a population migrate. The decision to migrate or to be a resident can be dependent on many...

We monitored the long-term residency of reef-associated ballan wrasse and sand-dwelling rays captured at the site of a potential future Marine Protected Area (MPA: Portelet Bay, Jersey) by implanting them with small transmitters and deploying underwater receivers inside the bay. Individual fish were detected at Portelet Bay for up to 618 days, but...

Direct measurement of predator feeding events would represent a major advance in marine trophic ecology. To date, devices available for empirically quantifying feeding in free-swimming fishes have relied on measuring stomach temperature, pH or physical motility, each of which has major practical limitations. We hypothesized that the considerable ph...

Sharks zigzag vertically through the water in a series of alternating ascending and descending segments, changing depth by a few tens of meters over a period of a few hundred seconds. This 'yo-yo' like behavior has several characteristic patterns, identifiable by the way the swimming and vertical velocities vary along the dive. We suggest that thes...

Many pelagic fishes exhibit 'yo-yo' diving behavior, which may serve several possible functions, including energy conservation, prey searching and navigation. We deployed accelerometers and digital still cameras on 4 free-ranging tiger sharks Galeocerdo cuvier, to test whether their vertical movements are most consistent with energy conservation or...

1. Animal search patterns reflect sensory perception ranges combined with memory and knowledge of the surrounding environment. 2. Random walks are used when the locations of resources are unknown, whereas directed walks should be optimal when the location of favourable habitats is known. However, directed walks have been quantified for very few spe...

The main Hawaiian Islands (MHI) are the principal breeding ground for humpback whales in the North Pacific. Over the past 3 decades, population recovery from whaling-era losses has resulted in a steady increase in the number of whales wintering in Hawaiian waters and a geographic expansion of their distribution in the MHI. Until recently, no existi...

Empirical data on the abundance and habitat preferences of coral reef top predators are needed to evaluate their ecological impacts and guide management decisions. We used longline surveys to quantify the shark assemblage at French Frigate Shoals (FFS) atoll from May to August 2009. Fishing effort consisted of 189 longline sets totaling 6,862 hook...

Sharks are found in association with main Hawaiian Island ocean fish farms more frequently and at higher densities than is typical for coastal Hawaiian waters. Sharks attracted to fish farms could potentially threaten human water users, interact negatively with other fisheries, and seasonal migrations could be disrupted if individuals become entrai...

Coral reef habitats in the Papahānaumokuākea Marine National Monument (PMNM) are characterized by abundant top-level predators such as sharks and jacks. The predator assemblage is dominated both numerically and in biomass by giant trevally (Caranx ignobilis) and Galapagos sharks (Carcharhinus galapagensis). A lower diversity of predatory teleosts,...

We equipped individual tiger (Galeocerdo cuvier Péron and Lesueur, 1822) and Galapagos (Carcharhinus galapagensis Snodgrass and Heller, 1905) sharks with both acoustic and satellite transmitters to quantify their long-term movements in the Papahanaumokuakea Marine National Monument (Northwestern Hawaiian Islands). Tiger sharks exhibited two broad p...

We tracked the long-term movements of 70 parrotfishes, surgeonfishes and goatfishes captured inside a small (1.3km2) marine protected area (MPA: Kealakekua Bay Marine Life Conservation District, Hawaii) by implanting them with small transmitters and deploying underwater monitoring devices inside the bay and along 100km of the adjacent west Hawaii c...

In order to investigate ontogenetic changes in diet and diet overlap between rohu (Labeo rohita) and common carp (Cyprinus carpio) in polyculture ponds, food preferences of different size classes of these fishes were quantified. Rohu diet consisted of both phytoplankton and zooplankton, and there was a distinct ontogenetic shift in the relative imp...

In order to better understand behaviour patterns of common carp Cyprinus carpio in aquaculture ponds, their diel grazing, swimming, resting and schooling behaviours were observed in six 1 m(2) tanks under simulated pond conditions. Each tank was fertilized to stimulate natural food production before starting experiments, and then stocked with three...

Shark cage diving is both popular and controversial, with proponents citing educational value and non-extractive use of natural resources and opponents raising concerns about public safety and ecological impacts. Logbook data collected 2004-2008 from two Oahu (Hawaii) shark cage diving operations were analysed to determine whether such voluntary re...

Little is known about the long-term movement patterns of most marine apex predators. A network of acoustic receivers was used to quantify the long-term movements of transmitter-equipped tiger sharks Galeocerdo cuvier Peron & Lesueur, 1822 in the Main Hawaiian Islands. Tiger sharks were wide-ranging, swam between islands and patrolled up to 109 km o...

Prototype acoustic 'business card' (BC) tags were deployed on 4 free-swimming Galapagos sharks Carcharhinus galapagensis associated with a shark ecotourism operation near Haleiwa, Hawaii, USA. These transmitter/receiver tags employed mobile peer-to-peer (MP2P) technology that allowed the tagged sharks to exchange codes among each other and to detec...

We quantified spatial dynamics and substrate impacts of snorkelers and SCUBA divers within four Hawaiian MPAs to determine: (1) whether coral reefs in these areas are being damaged by recreational activities, and (2) how damage might be mitigated. Observers secretly followed snorkelers and SCUBA divers, and used handheld Global Positioning System (...

Little is known about the feeding habits of large free ranging fish, due in large part to lack of an appropriate technique for quantifying feeding variables. A previous study demonstrated that changes in gastric pH can be used as a proxy for feeding events in free-ranging sharks. Here we describe the development of a new acoustic pH transmitter...

Gaps in our knowledge of basic fish ecology have provided impetus for development of novel “ecology tags” to detect and quantify hard to observe behaviors such as spawning, schooling and feeding. The acoustic environment is one source of potentially useful information about these behaviors. We implanted an acoustic recording tag (Bioacoustic Probe)...

Empirical data quantifying the long-term movement patterns of coral reef top predators are needed in order to design marine protected areas (MPAs) that will provide these fishes with effective, long-term protection. Acoustic telemetry was used to quantify the movements of a large coral reef top predator (Aprion virescens, Lutjanidae; Hawaiian name...

I used shoreline creel surveys to quantify fishing activities in and around a small (0.34km2) Marine Protected Area (MPA) in Hawaii (Waikiki Marine Life Conservation District). Spear fishing and shoreline pole & line fishing (angling) were the dominant fishing activities at Waikiki. Spear fishing had a greater overall impact on reef fishes than sho...

We need to understand the long-term movement patterns of coral reef top predators in order to design marine protected areas that will provide these animals with effective, long-term pro- tection. We used acoustic telemetry to quantify the movements of giant trevally, a large coral reef top predator, at 5 atolls in the Northwestern Hawaiian Islands...

The Northwestern Hawaiian Islands (NWHI) host a variety of large vertebrate animals including seabirds, green sea turtles (Chelonia mydas), Hawaiian monk seals (Monanchus schauislandi), and large teleost fish such as trevally (Family Carangidae) and several species of sharks. The air-breathing vertebrates have been the subjects of relatively contin...

We quantified bluespine unicornfish, Naso unicornis, movement patterns, home range size and habitat preferences in a small Hawaiian marine reserve. Bluespine unicornfish were site-attached to home ranges situated within the reserve boundaries and their movements were aligned with topographic features. Two different diel movement patterns (‘commutin...

The feasibility of long-term acoustic monitoring of coral reef fish movements was evaluated by quantifying transmitter retention times for captive bluefin trevally Caranx melampygus and detection patterns of transmitter-implanted free-ranging bluefin trevally. Wax-coated dummy transmitters (9 × 22 mm; 3.6 g) were surgically implanted into the gut c...

We used behavioural conditioning to demonstrate that sharks can detect changes in the geomagnetic field. Captive sharks were conditioned by pairing activation of an artificial magnetic field with presentation of food over a target. Conditioned sharks subsequently converged on the target when the artificial magnetic field was activated but no food r...

Movement patterns, site fidelity and growth were studied for giant trevally (Caranx ignobilis) inhabiting a marine reserve surrounding Coconut Island in Kaneohe Bay, off the Island of Oahu, Hawaii. Short-term movements of fish were determined by acoustic telemetry and long-term movements and growth were investigated with conventional tag and releas...

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. Mode of access: World Wide Web. Includes bibliographical references (leaves 113-134). Electronic reproduction. Also available by subscription via World Wide Web ix, 134 leaves, bound col. ill., maps 29 cm The effectiveness of a small (0.34km2) "no fishing" marine reserve (Waikiki Marine Life Con...