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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 Marine National Monument. We did not observe any inter-atoll movements but found that giant trevally were attached to core activity areas from which they made periodic atoll-wide excursions of up to 29 km. Within the core areas, the tagged fish exhibited diel habitat shifts. We identified Rapture Reef at French Frigate Shoals (FFS) atoll as a spawning site, where giant trevally form seasonal mating aggregations. Giant trevally that use Rapture Reef as their core daytime area live there year-round, whereas those that occupy other areas of FFS migrate to Rapture Reef in the summertime during specific phases of the moon. Although giant trevally were wide-ranging and would require large marine protected areas (e.g. entire atolls or islands) to protect their entire range, core activity areas and spawning sites for giant trevally could be contained within relatively small marine protected areas. Identification of spawning sites could assist in the establishment of focused marine protected areas that, while quite small in size, could have significant impact in preserving the spawning biomass of this species. Very large marine protected areas are not feasible in most heavily populated areas, hence effective alternative management strategies must be found for this fishery-targeted, wide-ranging top predator. We sug- gest using a combination of relatively small marine protected areas, to protect core activity areas and spawning sites for giant trevally, and conventional measures such as minimum size or 'slot' limits to further safeguard spawning stocks.

The distribution and interactions of aquatic organisms across space and time structure our marine, freshwater, and estuarine ecosystems. Over the past decade, technological advances in telemetry have transformed our ability to observe aquatic animal behavior and movement. These advances are now providing unprecedented ecological insights by connecting animal movements with measures of their physiology and environment. These developments are revolutionizing the scope and scale of questions that can be asked about the causes and consequences of movement and are redefining how we view and manage individuals, populations, and entire ecosystems. The next advance in aquatic telemetry will be the development of a global collaborative effort to facilitate infrastructure and data sharing and management over scales not previously possible.

BACKGROUND Global aquatic environments are changing profoundly as a result of human actions; consequently, so too are the ways in which organisms are distributing themselves through space and time. Our ability to predict organism and community responses to these alterations will be dependent on knowledge of animal movements, interactions, and how the physiological and environmental processes underlying them shape species distributions. These patterns and processes ultimately structure aquatic ecosystems and provide the wealth of ecosystem services upon which humans depend. Until recently, the vast size, opacity, and dynamic nature of the aquatic realm have impeded our efforts to understand these ecosystems. With rapid technological advancement over the past several decades, a suite of electronic tracking devices (e.g., acoustic and satellite transmitters) that can remotely monitor animals in these challenging environments are now available. Aquatic telemetry technology is rapidly accelerating our ability to observe animal behavior and distribution and, as a consequence, is fundamentally altering our understanding of the structure and function of global aquatic ecosystems. These advances provide the toolbox to define how future global aquatic management practices must evolve. ADVANCES Aquatic telemetry has emerged through technological advances in miniaturization, battery engineering, and software and hardware development, allowing the monitoring of organisms whose habitats range from the poles to the tropics and the photic zone to the abyssal depths. This is enabling the characterization of the horizontal and vertical movements of individuals, populations, and entire communities over scales of meters to tens of thousands of kilometers and over time frames of hours to years and even over the entire lifetimes of individuals. Electronic tags can now be equipped with sensors that measure ambient physical parameters (depth, temperature, conductivity, fluorescence), providing simultaneous monitoring of animals’ environments. By linking telemetry with biologgers (e.g., jaw-motion sensors), it is possible to monitor individual feeding events. In addition, other devices on instrumented animals can communicate with one another, providing insights into predator-prey interactions and social behavior. Coupling telemetry with minute nonlethal biopsy allows understanding of how trophic dynamics, population connectivity, and gene-level basis for organismal health and condition relate to movement. These advances are revolutionizing the scope and scales of questions that can be addressed on the causes and consequences of animal distribution and movement. OUTLOOK Aquatic animal telemetry has advanced rapidly, yet new challenges present themselves in coordination of monitoring across large-spatial scales (ocean basins), data sharing, and data assimilation. The continued advancement of aquatic telemetry lies in establishing and maintaining accessible and cost-effective infrastructure and in promoting multidisciplinary tagging approaches to maximize cost benefits. A united global network and centralized database will provide the mechanism for global telemetry data and will promote a transparent environment for data sharing that will, in turn, increase global communication, scope for collaboration, intellectual advancement, and funding opportunities. An overarching global network will realize the potential of telemetry, which is essential for advancing scientific knowledge and effectively managing globally shared aquatic resources and their ecosystems in the face of mounting human pressures and environmental change.

The rapid expansion of the use of passive acoustic telemetry technologies has facilitated unprecedented opportunities for studying the behavior of marine organisms in their natural environment. This technological advance would greatly benefit from the parallel development of dedicated methodologies accounting for the variety of timescales involved in the remote detection of tagged animals related to instrumental, environmental and behavioral events. In this paper we propose a methodological framework for estimating the site fidelity ("residence times") of acoustic tagged animals at different timescales, based on the survival analysis of continuous residence times recorded at multiple receivers. Our approach is validated through modeling and applied on two distinct datasets obtained from a small coastal pelagic species (bigeye scad, Selar crumenophthalmus) and a large, offshore pelagic species (yellowfin tuna, Thunnus albacares), which show very distinct spatial scales of behavior. The methodological framework proposed herein allows estimating the most appropriate temporal scale for processing passive acoustic telemetry data depending on the scientific question of interest. Our method provides residence times free of the bias inherent to environmental and instrumental noise that can be used to study the small scale behavior of acoustic tagged animals. At larger timescales, it can effectively identify residence times that encompass the diel behavioral excursions of fish out of the acoustic detection range. This study provides a systematic framework for the analysis of passive acoustic telemetry data that can be employed for the comparative study of different species and study sites. The same methodology can be used each time discrete records of animal detections of any nature are employed for estimating the site fidelity of an animal at different timescales., SCOPUS: ar.j, info:eu-repo/semantics/published

The influence of multiple anchored fish aggregating devices (FADs) on the spatial behavior of yellowfin (Thunnus albacares) and bigeye tuna (T. obesus) was investigated by equipping all thirteen FADs surrounding the island of Oahu (HI, USA) with automated sonic receivers (“listening stations”) and intra-peritoneally implanting individually coded acoustic transmitters in 45 yellowfin and 12 bigeye tuna. Thus, the FAD network became a multi-element passive observatory of the residence and movement characteristics of tuna within the array. Yellowfin tuna were detected within the FAD array for up to 150 days, while bigeye tuna were only observed up to a maximum of 10 days after tagging. Only eight yellowfin tuna (out of 45) and one bigeye tuna (out of 12) visited FADs other than their FAD of release. Those nine fish tended to visit nearest neighboring FADs and, in general, spent more time at their FAD of release than at the others. Fish visiting the same FAD several times or visiting other FADs tended to stay longer in the FAD network. A majority of tagged fish exhibited some synchronicity when departing the FADs but not all tagged fish departed a FAD at the same time: small groups of tagged fish left together while others remained. We hypothesize that tuna (at an individual or collective level) consider local conditions around any given FAD to be representative of the environment on a larger scale (e.g., the entire island) and when those conditions become unfavorable the tuna move to a completely different area. Thus, while the anchored FADs surrounding the island of Oahu might concentrate fish and make them more vulnerable to fishing, at a meso-scale they might not entrain fish longer than if there were no (or very few) FADs in the area. At the existing FAD density, the ‘island effect’ is more likely to be responsible for the general presence of fish around the island than the FADs. We recommend further investigation of this hypothesis.

We tested for presence or absence of multiple paternity in single litters from each of three congeneric shark species in Hawaii: the sandbar shark, Carcharhinus plumbeus, bignose shark, Car- charhinus altimus, and Galapagos shark, Carcharhi- nus galapagensis. Based on eight polymorphic microsatellite loci, we excluded paternity by a single sire in sandbar and bignose sharks, but could not exclude a single sire for the litter from the Galapagos shark. This study doubles the number of shark species tested for multiple paternity, and is the first demon- stration of multiple paternity in sandbar and bignose sharks.

Within the tropical and subtropical oceans, tuna forage opportunistically on a wide variety of prey. However, little is known about the trophic ecology of the smallest size classes which play an important role in stock assessments and fisheries management. The foraging behavior of yellowfin tuna, Thunnus albacares (23.5–154.0 cm FL), collected from nearshore Fish Aggregating Devices (FADs) around Oahu was studied using stable isotope and stomach contents analyses. Emphasis was placed on small juveniles. Yellowfin tuna changed their diets significantly between 45 and 50 cm forklength (ca. 1.5 kg). Smallest size classes fed on planktonic organisms inhabiting the shallow mixed layer, primarily larval stomatopod and decapod crustaceans, whereas larger tuna fed on teleosts and adult Oplophorus gracilirostris, a vertically migrating mesopelagic species of shrimp. When interpreting the variation in prey δ 15N values, we considered both their relative trophic position and δ 15N values of the nitrogen at the base of the food web. Based on the distinct diet shift of the yellowfin tuna, demonstrated by both isotope and stomach content analyses, we propose a critical mass threshold was reached at about 45 cm FL that enabled sufficient endothermic capability to allow tuna to access prey dwelling in deeper, colder water. These ontogenetic changes in foraging range and commensurate shift in diet of small tunas would affect their vulnerability to fishing pressure.

Nursery habitat use and growth rates of juvenile scalloped hammerhead sharks Sphyrna lewini were measured in a Hawai'i nursery (Kane'ohe Bay, O ¯ 'ahu) using a 28 mo tag-and- recapture study augmented by experimental determination of the relative age of neonate sharks. An estimated 7700 (±2240 SD) hammerhead sharks are born in Kane'ohe Bay each year. Neonates are born in the summer between May and September and had low retention (from 0.07 to 0.15, as a frac- tion of neonate population size) within the bay from Age 0 to Age 1. A primary cause of low retention appears to be mortality from starvation. Most juvenile sharks recaptured after short periods of time at liberty (

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 (‘commuting’ and ‘foraying’) were observed. Commuters made crepuscular migrations of several hundred meters between daytime foraging areas and nighttime refuge holes. Foraying fish did not partake in crepuscular migrations and utilized refuge holes both day and night. Two bluespine unicornfish were also nocturnally active. There was little direct evidence of dispersal from the reserve but differences in bluespine unicornfish abundance and size among reef habitat zones were consistent with ontogenetic habitat shifts. The influence of habitat topography on bluespine unicornfish movements suggests that gross habitat characteristics could be used to predict reef fish movements. This could provide a simple method for setting marine reserve boundaries at sites for which empirical fish movement data are unavailable.

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 release methods. Giant trevally appear to move to the Coconut Island marine reserve from the adjacent bay floor upon attaining a size of approximately 20–25 cm fork length. After several years spent frequenting the reserve, giant trevally move out of the bay into deeper water. Tracked fish spent considerable time within the marine reserve moving along the reef slope, but frequently ventured outside of the reserve boundaries. The recapture rate for tagged fish was 11%, with an average time at liberty of 346 days. Nearly one-third of recaptured fish were caught at distances greater than 3 km from the tagging site with maximum values demonstrating long-term (more than 7 years) and long-distance (30 km) movements. The protective function of the Coconut Island marine reserve for giant trevally is limited because the reserve is utilized by only a portion of the population, and even these fish regularly move outside of the refuge. © 2003 Elsevier B.V. All rights reserved.

The Hawaiian stingray, Dasyatis lata, is a common benthic elasmobranch in nearshore Hawaiian waters. Acoustic telemetry was used to track the movements of seven rays in Kaneohe Bay, Oahu, Hawaii. Rays were tracked continuously over 31–74 h periods. Geographical movements were analyzed to determine space utilization and rate of movement. Rays were found to utilize significantly larger activity spaces at night (0.83±0.70 km2) (mean±SD) than during the day (0.12±0.15 km2). Mean total activity space for rays tracked was 1.32±0.75 km2. Rates of movement were also significantly higher at night (0.34±0.30 km h-1) than during the day (0.15±0.22 km h-1). Average straight-line swimming speed was 0.64±0.16 km h-1, with a maximum observed swimming speed of 1.9 km h-1. Tidal stage had no effect on rate of movement. Comparison with previously published data on juvenile scalloped hammerhead sharks, Sphyrna lewini, in Kaneohe Bay revealed a high degree of overlap in habitat use and time of activity, suggesting possible ecological interactions between these two species.

SUMMARY The unique head morphology of sphyrnid sharks might have evolved to enhance electrosensory capabilities. The `enhanced electroreception' hypothesis was tested by comparing the behavioral responses of similarly sized carcharhinid and sphyrnid sharks to prey-simulating electric stimuli. Juvenile scalloped hammerhead sharks Sphyrna lewini and sandbar sharks Carcharhinus plumbeus oriented to dipole electric fields from the same maximum distance (approximately 30 cm) and thus demonstrated comparable behavioral-response thresholds (

Gastric evacuation and daily ration were studied in juvenile scalloped hammerhead sharks in Kāne'ohe Bay in order to better understand their ecology and role as apex predators in the marine environment. Three major variables known to affect the rate of gastric evacuation were manipulated: meal size, prey species, and temperature. Rates of gastric evacuation were faster than have previously been measured for sharks. The time for 80% of the meal weight (dry) to be evacuated ranged from 5.4 to 22.1 h. Daily ration was estimated using two different methods based on gastric evacuation rates and stomach content data. Estimates ranged from 2.12% to 3.54% of the body weight, which is relatively high compared to other elasmobranchs, but lower than estimates of maintenance ration for juvenile scalloped hammerheads. Data available for diet and growth of juvenile scalloped hammerhead sharks in Kāne'ohe Bay as well as data for their prey species suggest that these sharks may be surviving much of the time at consumption levels below maintenance ration.

Stomach content, capture method and capture location data were collected for 401 carangids captured during three annual 1-day fishing tournaments held at a coastal bay in Hawaii. Blue jack (Caranx melampygus), white jack (Caranx ignobilis) and island jack (Carangoides orthogrammus) were the most common species, accounting for 83.5, 8.5 and 5.2% of tournament catches, respectively. Geographical area fished consisted of a sheltered bay and the adjacent seaward coastal reef beyond. Area of capture and fishing method influenced species and size of fish captured. Small ( 500 mm) C. melampygus were captured outside Kaneohe Bay. Trolling (towing a surface lure) accounted for 80% of C. melampygus, 76% of C. orthogrammus and 55% of C. ignobilis captured. Differential vulnerability to trolling may be related to interspecific differences in diet; captured C. melampygus had fed primarily on fish whereas C. orthogrammus had consumed both fish and benthic crustaceans, and C. ignobilis had eaten mainly benthic crustaceans. Differences in diet may indicate resource partitioning between these sympatric and closely related species. For C. melampygus there was a consistent relationship between prey size and predator size. When conducted under scientific scrutiny, fishing tournaments can provide synoptic data on diet and gear vulnerability that would otherwise be very difficult to obtain.

Suitability of small (< 1 km2) marine reserves for protecting a commercially important endemic Hawaiian goatfish, Parupeneus porphyreus, was examined by quantifying goatfish habitat use, home range size and site fidelity in an existing marine reserve (Coconut Island in Kaneohe Bay, Hawaii). Five goatfish equipped with acoustic transmitters were tracked for up to 93 h each over 3–14 days. Daytime habitat use patterns of two of these fish were continuously monitored for one month using a fixed hydrophone hardwired to an onshore computer. Acoustically tagged fish showed consistent diel patterns of behavior, refuging in holes in the reef by day and moving over extensive areas of sand and coral rubble habitat at night. Remote monitoring of daytime habitat use by two goatfish revealed that the same daytime refuge was used by both fish for at least one month (the battery life of the transmitters). Home ranges of all fish were within the boundaries of the Coconut Island reserve suggesting that even small areas containing suitable habitat can make effective reserves for this species. A relatively low abundance of reproductive size P. porphyreus at Coconut Island in comparison with deeper areas may indicate an ontogenetic shift to deeper habitat in this species.

A Hawai, diverses flottilles de peche artisanale ou semi-industrielle concentrent leur effort de peche sur des DCP mouilles pres des cotes, sur des points d'agregation naturels dans la zone cotiere, sur des monts sous-marins au large, ou encore sur des bouees meteorologiques situees au large. Les palangriers de gros tonnage operent egalement dans la zone economique exclusive (ZEE) d'Hawai et au-dela. Ces conditions fournissent un cadre ideal pour des experiences de marquage/recapture afin d'etudier les deplacements, les temps de residence, les taux d'echanges et la vulnerabilite du thon obese (Thunnus obesus) et de l'albacore (Thunnus albacares) dans la ZEE d'Hawaii. Des donnees preliminaires de recapture indiquent que les DCP, les plateaux recifaux des iles, ainsi que les monts sous-marins exercent une tres forte influence sur la capturabilite des thons. Les taux de recapture provenant de ces sites sous-estiment largement les retours des thons dont le marquage a ete effectue au large. Ainsi, le 31 aout 1999, un total de 15 387 thons obeses et albacores, respectivement de 29 a 133 cm et 26 a 143 cm (longueur a la fourche), soit une moyenne respective de 59,8 ± 14,1 cm et 58,4 ± 17,3 cm, ont ete marques et relâches dans la ZEE d'Hawai. Les taux de recapture pour les deux especes sont similaires, avec un taux de recapture total de 10,3 %. Le lieu des marquages reflete l'importance du comportement associatif et gregaire des thons sur leur vulnerabilite ; mont sous-marins et DCP comptent pour 72,4 % et 23,5 % de l'ensemble des remises en liberte. Dans le groupe d'iles principales d'Hawaii (a l'exception des monts sous-marins et des bouees oceanographiques), 83,1 % de toutes les recaptures ont ete faites sous les DCP ancres et 11,9 % des recaptures viennent du plateau corallien ou des zones de regroupement des thons, a proximite des iles ou ces deux especes deviennent vulnerables aux palangres « a main » (verticales). Ces etudes n'etant pas terminees, de nouvelles recaptures a long terme apporteront de plus en plus d'informations sur les deplacements et la vulnerabilite du thon obese et de l'albacore pendant leur croissance, leurs deplacements et leur recrutement dans les differentes zones de peche.

Des albacores et des thons obeses (Thunnus albacores et Thunnus obesus) ont ete marques et relâches entre aout 1995 et decembre 1997 au mont sous-marin Cross et aux bouees meteorologiques de la NOAA a environ 200 milles nautiques au sud d'Honolulu. Les donnees de marquage et de recapture stratifiees en 5 sites et un modele de transfert global a ete utilise pour estimer la mortalite naturelle, la mortalite par peche et le taux de transfert entre les 5 sites. Le thon obese demeure davantage au mont sous-marin Cross, et est moins vulnerable a la peche, que l'albacore. La peche au niveau du mont sous-marin Cross, compte pour environ 5 % de la mortalite totale pour les deux especes. L'albacore est une composante majeure des captures au niveau des dispositifs de concentrations de poissons (DCP) a Hawai. Le taux d'immigration du mont sous-marin Cross, vers les DCP cotiers, est tres faible pour les deux especes. La mortalite par peche au niveau du mont sous-marin est consequente mais n'a pas d'impact defavorable sur les populations, que ce soit au mont sous-marin Cross ou au niveau des DCP cotiers.

Externally and internally implanted sonic transmitters were used to track the movements of eight tiger sharks (Galeocerdo cuvier) ranging between 200 and 417 cm total length (TL), captured by hook-and-line on the south coast of Oahu, Hawaii, between 1993 and 1997. Attachment of the transmitters was facilitated by the fact that captured sharks exhibited tonic immobility when restrained and inverted at the side of the tagging vessel. Three common themes emerged from the horizontal movements of the tracked sharks: (1) offshore movements away from the island, (2) extended periods of directed, “straight-line” swimming, (3) orientation to the Penguin Banks – a shallow bank located ≃35 km from the release point. In shallow water ( 300 m) they swam within the mixed layer at depths of ∼80 m. One shark dove briefly to 335 m. The average estimated swimming speed of sharks traversing open water was 0.29 body length (BL) s−1. Two sharks were recaptured after termination of the tracks; one of these sharks was recaptured twice, with a total time at liberty of 377 d. The data suggest that Hawaiian tiger sharks move within large home ranges and that they can efficiently navigate between distant parts of their range, even when this requires crossing open ocean waters.

A new acoustic transmitter for monitoring the tailbeat frequency of free-swimming fishes and sharks is described. The transmitter is externally mounted on the fish's caudal peduncle and produces an acoustic pulse with every lateral movement of the tail. Field tests on obligate-swimming juvenile scalloped hammerhead sharks (Sphyrna lewini) show these transmitters accurately telemeter tailbeat deflections from free-swimming sharks. Tests in a flume show sharks with transmitters work harder and swim slower than sharks without transmitters, but these laboratory data can be used to correct for instrument artifacts on free-swimming sharks. A shark tracked with a tailbeat-sensing transmitter exhibited similar movement and activity patterns to shark pups tracked with smaller, orally inserted internal transmitters. The similarity of tracks indicate that the shark equipped with the tailbeat transmitter behaved normally. Thus, this new transmitter design offers a cost-effective, minimally intrusive method for accurately measuring activity rate and energy consumption of active fishes and sharks in the field.

The short- and long-term movement patterns of blue trevally (Caranx melampygus) were monitored using a combination of sonic tracking and tag-and-release techniques. All fish were captured and released on the patch reef surrounding Coconut Island in Kaneohe Bay, Oahu, Hawaii, which has been a no-fishing conservation zone for over 30 years. Sonic tracking produced fine-scale movement data from five fish for periods spanning up to 18 days. All fish displayed diel movement patterns within consistent home ranges, which encompassed different parts of the reef during the night than during the day. Movements were predominantly along the walls of the patch reef, with occasional forays to nearby sections of adjacent reefs. Four hundred and ten fish were tagged and released on the Coconut Island reef, and the recapture sites of 85 recaptured fish indicated that most did not move far from their point of release; 75.5% were recaptured within 0.5 km of their release points. Time at liberty ranged from 4 to 454 days, and distance between release and recapture sites was not related to time at liberty. Some fish were observed many times in the same areas over periods of several months. Both the tracking and recapture data indicate strong site fidelity in this species and low occurrence of long distance emigration. These behavioral traits suggest that successful husbandry of this species may be accomplished through the use of management practices such as establishing no-fishing zones.

Depth-sensitive ultrasonic transmitters monitored the horizontal and vertical movements of 12 juvenile (

Background The scalloped hammerhead shark, Sphyrna lewini, is a large endangered predator with a circumglobal distribution, observed in the open ocean but linked ontogenetically to coastal embayments for parturition and juvenile development. A previous survey of maternal (mtDNA) markers demonstrated strong genetic partitioning overall (global ΦST = 0.749) and significant population separations across oceans and between discontinuous continental coastlines. Methodology/Principal Findings We surveyed the same global range with increased sample coverage (N = 403) and 13 microsatellite loci to assess the male contribution to dispersal and population structure. Biparentally inherited microsatellites reveal low or absent genetic structure across ocean basins and global genetic differentiation (FST = 0.035) over an order of magnitude lower than the corresponding measures for maternal mtDNA lineages (ΦST = 0.749). Nuclear allelic richness and heterozygosity are high throughout the Indo-Pacific, while genetic structure is low. In contrast, allelic diversity is low while population structure is higher for populations at the ends of the range in the West Atlantic and East Pacific. Conclusions/Significance These data are consistent with the proposed Indo-Pacific center of origin for S. lewini, and indicate that females are philopatric or adhere to coastal habitats while males facilitate gene flow across oceanic expanses. This study includes the largest sampling effort and the most molecular loci ever used to survey the complete range of a large oceanic predator, and findings emphasize the importance of incorporating mixed-marker analysis into stock assessments of threatened and endangered shark species.

Although a growing body of evidence has indicated that tuna can thermoregulate and have body temperatures that are decoupled from immediate changes in ambient temperature, demonstrating the extent and time-course of body temperature changes in tuna moving through their natural environments has proved to be elusive. Here we use body temperature data telemetered from free-ranging fish to demonstrate short-latency physiological thermoregulation in bigeye tuna. We used a recently developed modeling system to determine the magnitude and time-course of the whole-body thermal conductivity changes that would result in the body temperature changes observed in fish in the wild. The results indicate rapid, 100 to 1000-fold changes in whole-body thermal conductivity that occur in response to quickly changing ambient temperatures. Coupling this physiological response with behavioral thermoregulation expands the foraging space of these animals by permitting activity in wide ranges of water temperatures and depths.

A feeding bioassay which uses agar discs was developed for evaluating chemosensory stimuli influencing ingestive behavior in Penaeus vannamei . Agar disc hardness and preventing the shrimp from placing their mouthparts directly onto the stimulus discs were important aspects of the bioassay design. The palatability assay required only small amounts of stimuli, was suitable for rapid screening of a wide variety of compounds, and was independent of factors such as texture or size of feed pellets. The most effective stimulus tested was shrimp-head offal extract, indicating the best use of this material may be as a flavorant rather than as a source of nutrients. Greatest biological activity was in the

(1) Dalhousie University, 1355 Oxford St., Halifax, Nova Scotia Canada B3H 4J1, Email: rodor@oceanleadership.org (2) IRD HEA, BP 5045, 34032 Montpellier Cedex 1, Montpellier, France, Email: dagorn@ird.fr (3) Hawaii Institute of Marine Biology, University of Hawaii, P.O. Box 1346, Coconut Island, Kaneohe, Hawaii 96744, USA, Email: kholland@hawaii.edu (4) Bedford Institute of Oceanography, 1 Challenger Drive, P. O. Box 1006, Dartmouth, Nova Scotia, Canada, B2Y 4A2, Email: JonsenI@mar.dfo-mpo.gc.ca (5) POST, Vancouver Aquarium, P. O. Box 3232, Vancouver, British Columbia, Canada, V6B 3X8, Email: jcpayne@u.washington.edu (6) Rhodes University, Grahams Town, South Africa, Email: w. sauer@ru.ac.za (7) Marine Research Laboratories, Tasmanian Aquaculture & Fisheries Institute, University of Tasmania, Private Bag49, Hobart, Tasmania 7001, Australia, Email: Jayson.Semmens@utas.edu.au (8) Faculty of Science, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada, Email: mstokesb@dal.ca (9) Bedford Institute of Oceanography, 1 Challenger Drive, P. O. Box 1006, Dartmouth, Nova Scotia, Canada, B2Y 4A2, Email: SmithPC@mar.dfo-mpo.gc.ca (10) The Atlantic Salmon Federation, P. O. Box 5200, St. Andrews, New Brunswick, Canada, E5B 3S8, Email: FWhoriskey@Dal.ca

We report the results of a series of experiments to test the utility of acceleration data-loggers for determining the energy expenditure of juvenile hammerhead sharks ( Sphyrna lewini ). In one experiment, three sharks were instrumented with miniature acceleration data-loggers and swum in a Brett-style respirometer at a range of speeds. For all three sharks, significant linear relationships were obtained between mean oxygen consumption (M · o 2 ) and Partial Dynamic Body Acceleration in the lateral and dorso-ventral axes (PDBA y , z ) with high predictive power ( r 2 > 0.71). In a second experiment, PDBA was measured for sharks swimming freely in circular tanks. The free-swimming sharks exhibited wide ranges of PDBA y , z ; routine swimming was characterised by low PDBA y , z (0.01–0.12 g) whereas unsteady swimming, (especially fast-start swimming of > 1 g) was characterised by high PDBA y , z . Despite initial evidence of linearity in the oxygen consumption vs. PDBA relationship, incorporating previous estimates of standard metabolic rate of hammerhead sharks suggests a non-linear fit. Further work is needed to establish the exact shape of the relationship beyond the narrow range of speeds that hammerhead pups could be exercised in this study, particularly the low swimming speeds which are frequently observed in free-swimming animals.

Understanding the movements of marine organisms in space and time has become a key area of research in support of management and conservation decision-making processes. This includes the optimal design of networks of marine reserves, as movements of fish are a major determinant for the reserve effect (increase in size and number inside reserves) and spillover effect (emigration from reserves). The increasing use of acoustic telemetry techniques, particularly passive acoustic arrays, is providing much of that information, but studies have typically used one specific approach at a specific spatial-temporal scale. We studied movement patterns, habitat use and dispersal in the red porgy, Pagrus pagrus (a commercially important species) in the Azores islands, mid-north Atlantic, with the aim of supporting the design of marine reserves that would protect local populations while enhancing fisheries. Movements were quantified using: (1) short-term active acoustic tracking; (2) multi-year passive acoustic monitoring; and (3) standard tag-release experiments in the Faial Channel. We found the short-term home ranges of red porgy to be quite large for a reef fish – up to 50 ha. Furthermore, frequent short-term displacements of up to 9 km and periodic absences from main core activity areas indicate that HR varies considerably in size and location throughout the year. Home range expansion occurred mostly during the protracted period of spawning activity, but we saw no evidence for spawning aggregations. We found evidence that individuals of smaller size utilize larger home ranges and are less site-specific, supporting the hypothesis that dispersal in the red porgy is largely determined by ontogenic changes. Large individual variability in both short-term and long-term movement patterns accounted for some emigrations from tagging sites and for one documented relocation. These findings indicate that adequate protection of subpopulations of red porgy will not be achieved using small, isolated reserves (1 to 5 km2), but reserves of size in the order of tens of km2 and spaced a few kilometers apart should provide protection while promoting emigration (spillover) of red porgy from reserves to neighboring grounds. This study shows that the combination of spatial and temporal scales and approaches is needed to capture a realistic picture of the full suite of spatial behaviors used throughout a species’ life history.

Archival and acoustic tagging were carried out in the exclusive economic zone (EEZ) of Papua New Guinea (PNG) in the western Pacific Ocean during 2006–07 to investigate the vertical behavior of tropical tuna found in association with large arrays of anchored FADs. Industrialized purse-seine fishing on anchored FADs has existed in the PNG EEZ for more than a decade. Archival tags were implanted in bigeye (n = 40; length 40–90 cm FL) and yellowfin (214; length 42–126 cm FL) tuna in the Bismarck and Solomon Seas. Acoustic tags were released in the same areas in 195 tuna (10 bigeye, 116 yellowfin, 69 skipjack). In addition, 27 tuna (eight bigeye, 19 yellowfin) received both an archival and an acoustic tag. Archival tag data from 32 recaptures were categorized into the three distinct vertical behavior modes for bigeye, and the three distinct modes for yellowfin that have been described in the published literature. The depth distribution for each of the categories was then calculated to examine potential vulnerability to industrial purse-seine capture in this region. A region-specific analysis was considered important as oceanographic conditions in this region are distinctly different to the conditions reported in the published literature from other locations. Analysis of acoustic data reveals short residence times at FADs and strong school cohesion. Vertical behavior of skipjack, yellowfin and bigeye tuna that were simultaneously present at the same FAD, as determined by depth transmitting acoustic tags, suggested some vertical separation of these species. However, there was a high degree of depth overlap, particularly during early morning hours when purse seining on floating objects normally occurs in this region. This overlap limits the potential for targeting particular species or size classes of tuna through fishing depth selection. This observation was confirmed from the archival tag depth records for yellowfin and bigeye during the same time period regardless of behavior type exhibited. The recapture of bigeye and yellowfin tuna implanted with both acoustic and archival tags allowed the observation of the natural vertical behavior of these fish when they were close to anchored FADs equipped with acoustic receivers. Occupation of shallow (

Reproductive biology and habitat preferences of the white trevally, Pseudocaranx dentex (Carangidae), were studied in the Azores islands, central north Atlantic, to determine the spatial and seasonal dynamics of habitat use of immature and mature fish. The sex ratio was close to 1:1 and fish matured at about 30 cm fork length. There were no differences in the maturation or length-weight relationships between sexes. The spawning season lasts from June to September. Underwater visual censuses showed that schools of mature individuals preferentially aggregate around the summits of offshore reefs during the spawning season. In contrast, schools of smaller, immature fish use inshore habitats all year round. Our data support the hypothesis that offshore reefs are a preferential spawning habitat of larger white trevally, and most possibly for a number of visitor pelagic predators as well. Inverse relationships between exploitation levels, abundance and size composition at the two different islands suggest that the summer fishery targeting trevally schools around offshore reefs has negatively impacted the population. These findings bring additional ecological and management relevance to offshore reefs.

Automated acoustic receivers are now widely used by biologists to study the behavior of fish. However, currently available acoustic receivers require physical recovery of the units to download stored data. Such operation is often difficult in remote study areas like in the open ocean. We present a new satellite-linked acoustic receiver (Vemco VR3-Argos) that allows downloading data through a satellite uplink (Argos). The VR3-Argos can last up to one year, sending GPS positions and tag data at regular time intervals. We illustrate the advantages of this new technology with tagging data from 121 fish of seven species (yellowfin tuna, bigeye tuna, skipjack tuna, wahoo, dolphinfish, silky shark and oceanic triggerfish) caught and released around drifting fish aggregating devices (FADs) in the Western Indian Ocean, far from any land. In opposition with the classic acoustic receivers (Vemco VR2), the use of VR3-Argos allowed to collect data for several weeks after leaving the drifting FADs. Maximum residence times of 3 days for bigeye tuna, 7 days for skipjack, 8 days for wahoo, 10 days for silky shark and 15 days for yellowfin tuna, dolphinfish and oceanic triggerfish could be recorded. VR2 and VR3-Argos are equivalent in terms of quality of residence times data, however depth data obtained through satellites are aggregated in 8 classes for compression purposes, which leads to a loss of precision available with raw data. Future directions of this technology are discussed. des zones eloignees. Les recepteurs acoustiques automatiques sont maintenant largement utilises par les biologistes pour etudier le comportement des poissons. Cependant, les recepteurs acoustiques actuellement disponibles necessitent leur recuperation physique pour charger leurs donnees. Cette operation est souvent difficile dans des zones d'etude eloi- gnees comme en haute mer. Nous presentons un nouveau recepteur acoustique avec liaison satellite (Vemco VR3-Argos) qui permet de recuperer les donnees a travers une liaison satellite (Argos). Le VR3-Argos peut fonctionner plus d'un an, envoyant des donnees GPS et des donnees de marques a intervalles reguliers. Nous illustrons les avantages de cette nou- velle technologie avec des donnees de marquage de 121 poissons de 7 especes differentes (thon albacore, thon obese, listao, thazard, coryphene, requin soyeux, baliste oceanique) captures et relâches autour de dispositifs de concentration de poissons (DCP) derivants dans l'Ouest de l'ocean Indien, loin de toute terre. Au contraire des recepteurs acoustiques classiques (Vemco VR2), l'utilisation du VR3-Argos permet de recolter des donnees plusieurs semaines apres avoir quitte les DCP. Des temps de residence maximum de 3 jours pour le thon obese, 7 jours pour le listao, 8 jours pour le thazard, 10 jours pour le requin soyeux, et 15 jours pour le thon albacore, la coryphene et le baliste oceanique ont pu etre enregistre. Les VR2 et VR3-Argos sont equivalents en termes de qualite de donnees de temps de residence, mais les donnees de profondeur de nage des poissons, obtenues par liaison satellite, sont agregees en 8 classes pour des soucis de compression, ce qui amene a une perte de precision disponible dans les donnees brutes. Les futurs developpements de cette technologie sont discutes.

Yellowfin tuna (Thunnus albacares) are known to preferentially occupy the Surface mixed layer above the thermocline and it has been Suggested that they are physiologically restricted to water lerriperatt.11-CS no more than 8 degrees C colder than Surface waters. However, we here report for dive data acquired from a large yellowfin tuna which demonstrate for the first time that this species is indeed capable of making prolonged dives into deep cold waters. A yellowfin tuna (134 cm fork length) caught near ail anchored fish aggregating device (FAD) in the Seychelles (Western Indian Ocean) was equipped with all internally implanted archival tag and released. The fish was recaptured 98 days later. As predicted for this species, this fish spent 85% of its time shallower than 75 in (maximum thermocline depth experienced by the fish) but, over the Course of the track, it performed three deep dives to 578 in, 982 In and 1160 In. Minimum ambient water temperatures recorded Lit these depths were 8.6 degrees C, 7.4 degrees C and 5.9 degrees C respectively and varied by up to 23.3 degrees C from surface temperatures. The fish spent 8.3% of its time in waters more than 8 degrees C colder than the surface layer and daily experienced a wide range of sea temperatures (mode at 15- 16 degrees C) and of temperatures of the gut cavity (mode at 6 degrees C). The reason for these dives call not be known. These depths and temperatures significantly exceed those reported ill the literature so far and clearly demonstrate that this species has the physiological and behavioral ability to penetrate deep cold sections of the ocean.

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 reward was presented thereby demonstrating that they were able to sense the altered magnetic field. This strong response provides a robust behavioural assay that could be used to determine how sharks detect magnetic fields and to measure detection thresholds.

The authors acknowledge the National Oceanic and Atmospheric Administration (National Marine Sanctuaries Program), University of Hawaii Sea Grant and the State of Hawaii (Department of Land and Natural Resources) for providing funding to support a variety of shark research projects that collectively made this study possible. 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 grow rather slowly in Hawaii compared to other regions, but this may have been an artifact of the method used to estimate growth (unvalidated vertebral ring counts) compounded by small sample size and narrow size range. Since 1993, the University of Hawaii has conducted a research program aimed at elucidating tiger shark biology, and to date 420 tiger sharks have been tagged and 50 recaptured. All recaptures were from Hawaii except a single shark recaptured off Isla Jacques Cousteau (24 degrees 13'17 '' N 109 degrees 52'14 '' W), in the southern Gulf of California (minimum distance between tag and recapture sites = approximately 5,000 km), after 366 days at liberty (DAL). We used these empirical mark-recapture data to estimate growth rates and maximum size for tiger sharks in Hawaii. We found that tiger sharks in Hawaii grow twice as fast as previously thought, on average reaching 340 cm TL by age 5, and attaining a maximum size of 403 cm TL. Our model indicates the fastest growing individuals attain 400 cm TL by age 5, and the largest reach a maximum size of 444 cm TL. The largest shark captured during our study was 464 cm TL but individuals >450 cm TL were extremely rare (0.005% of sharks captured). We conclude that tiger shark growth rates and maximum sizes in Hawaii are generally consistent with those in other regions, and hypothesize that a broad diet may help them to achieve this rapid growth by maximizing prey consumption rates. Publisher PDF

Acoustic telemetry techniques were adapted for use with a kayak to facilitate tracking of species that range into shallow habitats that are inaccessible to even small outboard motor powered vessels. Low cost and portability make the tracking kayak a potentially useful tool for tracking aquatic animals in a wide variety of marine and freshwater environments. In the present study, blue-spined unicomfish (Naso unicornis, Acanthuridae) were successfully tracked for periods of up to 22 days in shallow high-energy fringing reef habitat in a Hawaii marine reserve (Waikiki Marine Life Conservation District-MLCD). To date all unicomfish tracked were highly site-attached to well-defined home ranges and showed similar diel patterns of behaviour; refuging within holes in the reef by night and moving to a separate daytime area. Unicomfish home ranges were completely encompassed by the boundaries of the 0.32 km2 MLCD.

Baseline data on life-history characteristics of elasmobranchs are often lacking before fisheries exploitation, hindering successful management and conservation of affected species. Age, growth and maturity estimates were determined for the brown stingray, Dasyatis lata, an abundant benthic predator in Hawai’i’s coastal ecosystems, from an unfished population off Oahu, Hawai’i. Age estimates ranged from 0 to 28 years for females and from 0 to 25 years for males. Annual growth-band deposition was verified through marginal increment and centrum edge analysis, as well as recapture of two stingrays marked with oxytetracycline. Multiple growth models were fitted to disk width (DW) and weight-at-age data and evaluated for biological realism and statistical fit. Logistic growth functions best described growth of male and female stingrays, whereas no support was found for von Bertalanffy growth models. Females attained larger sizes (L∞) and exhibited lower growth coefficients (k) than did males. Median size and age at first maturity was estimated to be 104.9 cm DW (15 years) for females and 74.9 cm DW (8.3 years) for males. These life-history characteristics highlight the importance of obtaining baseline data before fisheries are established and indicate that any fishery for brown stingrays should be managed using conservative management strategies.

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 entrained around farms throughout the year. We hypothesised that smaller coastal species would reside near farms, whereas more wide-ranging species would associate with farms only for short periods. We utilised passive acoustic telemetry to monitor the movements and behaviour of sandbar (Carcharhinus plumbeus) and tiger (Galeocerdo cuvier) sharks adjacent to two open ocean fish farms in Hawaii. Approximately half the tagged sandbar sharks showed site fidelity to the farms, with some individuals being detected repeatedly for 2.5 years. Sandbar sharks moved seasonally to the west coast of Oahu, suggesting that fish farms are not disrupting natural seasonal cycles in this species. Tiger sharks tagged near the cages were more transient, and showed much shorter residence times although some individuals returned sporadically to the cages over the 3-year period. Ocean fish cages appear to aggregate sandbar sharks, but are only ‘visited’ by tiger sharks. Although threats to public safety are probably minimal, the ecological effects of aggregating top-predators are still unknown.

Yellowfin tuna enhance their hunting success in the vast pelagic environment by using their sense of smell to detect intact (uninjured) prey that are beyond visual range. However, the olfactory cues that tuna use would normally face huge and rapid dilution in the open ocean. We demonstrate that these prey odors are complexed within biologically derived lipid structures that probably delay the dilution of the amino acids to subthreshold concentrations and provide persistent arousal and search cues for the tuna. This may be the first demonstration of an extracorporeal biological function for liposomes. Tuna may also form “chemical search images” to maximize feeding efficiency. We demonstrate that the amino acid profiles of various prey species are consistent over time and between schools, which makes the formation of search images feasible.

A review of papers published on billfish biological research since the 1988 Billfish Symposium highlights the important role these symposia play in disseminating billfish research results and also shows that progress since 1988 has been slow, especially when compared with tuna and other pelagic fishes. One reason for the disparity is that marlin have not yet been successfully held in captivity. Progress has been made in elucidating the trophic biology of billfish and these data are helping to build models of pelagic ecosystem dynamics. The deployment of several types of electronic tags has expedited advances in understanding the short-term movements and depth distribution of billfish, but long-term tracks remain elusive. In part, this may be because insufficient effort has been directed at developing methods for restraining marlin for tag attachment or implantation. Light-based geolocation techniques show great promise for elucidating billfish movements, but appropriate scientific rigour must be applied to the publication of these data. Several suggestions for advancing billfish research are presented.

Acoustic telemetry techniques have been adapted for use with small boats to facilitate tracking of nearshore reef species. In addition to permitting tracking in areas where manoeuvrability and quick responses are required, the system has modest operating costs that make tracking experiments a viable option for a wide range of researchers. Tracking and communication equipment can be powered for several days by a single 12-V 8D truck battery. Current topics in shark biology that are amenable to these tracking techniques are discussed. For instance, hammerhead pups have been tracked on their natal grounds for periods of up to 13 days. Their daytime movements appeared to be restricted to a well defined 'core area' where a school of sharks hovered between 1 and 3 m off the lagoon floor. At night, the sharks became more active, expanding their range of movements before returning to the core area the next morning.

Yellowfin tuna can detect and distinguish between odors of intact prey organisms, responding to odor quality of various prey rinses with different amino acid profiles. Chemical fractions of natural prey odors and synthetic mixtures of amino acids are less effective than whole natural rinses. Assuming uniform dilution, tuna can detect amino constituents of prey odors at about 10−11 M. Intensity of the behavioral response is modified by hunger. Feeding experience with new prey causes a gradual shift to maximum responses to its odor. We propose that one of the functions of the tuna's olfactory system is to form “chemical search images” which focus food search behavior for specific prey. The search image is thought to be modifiable and to be induced by prevailing prey abundance, so as to optimize the predator's feeding efficiency.

Two assays, a conditioned feeding response and a conditioned cardiac reflex, were developed to place previous electrophysiological, biochemical and gradient detection data into an organismal sensitivity perspective. Both assays yielded consistent chemosensory detection thresholds for several amino acids. The resultant stimulus effectiveness hierarchy is in very good agreement with biochemical binding data and the threshold values are quite similar to those obtained electrophysiologically. Thresholds ranged from 1×10 −9 M for the most effective stimuli (e.g., L-cysteine, L-arginine) to 1×10 −7 M for the least effective stimulus (glycine). Unlike previous applications of the cardiac conditioning technique, the present study extensively describes the methodology and the various response characteristics and compares the resultant thresholds with those obtained using a behavioral assay. Results obtained using the two techniques were in excellent agreement. Contrary to previous findings, the cutaneous gustatory system was capable of mediating both types of conditioned response. The behavioral implications of high gustatory sensitivity are discussed.

The roles of olfaction and gustation in feeding arousal and food locating behavior are described for the first time for a marine teleost. The external taste sense located on the chin barbels of the goatfish mediates both arousal and searching in response to diluted prey homogenate and rinse of intact live prey. Electrophysiological monitoring of the barbel nerve (VII) reveals a sensitivity to amino acids dominant in prey tissues, but not to those present in trace amounts.

Animal telemetry is the science of elucidating the movements and behavior of animals in relation to their environment or habitat. Here, we focus on telemetry of aquatic species (marine mammals, sharks, fish, sea birds and turtles) and so are concerned with animal movements and behavior as they move through and above the world’s oceans, coastal rivers, estuaries and great lakes. Animal telemetry devices (“tags”) yield detailed data regarding animal responses to the coupled ocean–atmosphere and physical environment through which they are moving. Animal telemetry has matured and we describe a developing US Animal Telemetry Network (ATN) observing system that monitors aquatic life on a range of temporal and spatial scales that will yield both short- and long-term benefits, fill oceanographic observing and knowledge gaps and advance many of the U.S. National Ocean Policy Priority Objectives. ATN has the potential to create a huge impact for the ocean observing activities undertaken by the U.S. Integrated Ocean Observing System (IOOS) and become a model for establishing additional national-level telemetry networks worldwide. Telemetry can provide environmental, behavioral and physiological data in near-real time, or by use of archival tags in which the data are stored or later transmitted to satellites. Aquatic animal species tagged have ranged from 6-g salmon smolts to 150-ton whales. Detailed observations of animal movements and behavior in relation to critical habitats in their aquatic environment have significantly improved our understanding of ecosystem function and dynamics. These observations are critical for sustaining populations, conserving biodiversity and implementing ecosystem-based management through an increased understanding of ecosystem structures, functions, and processes, as well as their importance to ecosystem services and values. Sensors carried by tagged animals have come of age and deliver high-resolution physical oceanographic data at relatively low costs. Animals are particularly adept at helping scientists identify critical habitats, spawning locations, and important oceanographic features (e.g., fronts, eddies and upwelling areas). They also provide important insights into regions of the oceans that are difficult and expensive to monitor (e.g., offshore environments, Arctic). This paper focuses on how to integrate an operational ATN into U.S. IOOS. The development of U.S. IOOS initially focused on the acquisition and integration of physical and chemical oceanographic data. With this system now operational, U.S. IOOS is ready to add the acquisition of relevant biological observations, and to enhance the acquisition of physical and chemical oceanographic observations via ATN platforms. A U.S. ATN observing system that monitors aquatic life on a range of temporal and spatial scales could yield both short- and long-term benefits, fill oceanographic observing and knowledge gaps, and advance many of the National Ocean Policy Priority Objectives. ATN has the potential to create a huge impact for the ocean observing activities undertaken by IOOS and become a model for establishing additional national-level telemetry networks worldwide.

Biologging technology has enhanced our understanding of the ecology of marine animals and has been central to identifying how oceanographic conditions drive patterns in their distribution and behavior. Among these environmental influences, there is increasing recognition of the impact of dissolved oxygen on the distribution of marine animals. Understanding of the impact of oxygen on vertical and horizontal movements would be advanced by contemporaneous in situ measurements of dissolved oxygen from animal-borne sensors instead of relying on environmental data that may not have appropriate spatial or temporal resolution. Here, we demonstrate the capabilities of dissolved oxygen pop-up satellite archival tags (DO-PATs) by presenting the results from calibration experiments and trial deployments of two prototype tags on bluntnose sixgill sharks (Hexanchus griseus). The DO-PATs provided fast, accurate, and stable measurements in calibration trials and demonstrated high correlation with vertical profiles obtained via traditional ship-borne oceanographic instruments. Deployments on bluntnose sixgill sharks recorded oxygen saturations as low as 9.4 % and effectively captured the oceanography of the region when compared with World Ocean Atlas 2013 values. This is the first study to use an animal-borne device to autonomously measure and record in situ dissolved oxygen saturation from non-air-breathing marine animals. The DO-PATs maintained consistency over time and yielded measurements equivalent to industry standards for environmental sampling. Acquiring contemporaneous in situ measurements of dissolved oxygen saturation alongside temperature and depth data will greatly improve our ability to investigate the spatial ecology of marine animals and make informed predictions of the impacts of global climate change. The information returned from DO-PATs is relevant not only to the study of the ecology of marine animals but will also become a useful new tool for investigating the physical structure of the oceans.