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Thinking deeper: Uncovering the mysteries of animal movement in the deep sea
Abstract
Advances in biotelemetry have revealed the movement behaviours of many terrestrial and shallow-water organisms, contributing critical insight for their conservation and management. However, persistent technological and logistical challenges have thus far impeded the implementation of biotelemetry in the deep sea. Despite these limitations, innovations in telemetry technology, experimental design, and animal handling have allowed the study of 13 families of deep-water fishes to date, providing movement records spanning from surface waters down to 5900 m depth and across nearly all of the world's oceans. Telemetry devices employed in deep-sea tracking studies have included both commercially available, and custom-built transmitters belonging to multiple tag categories: acoustic transponders/code-activated acoustic transponders, acoustic transmitters (coded and continuous, e.g., ‘pingers’), pop-up satellite archival tags, and archival tags (data loggers). Specially adapted tagging approaches, including in situ methods such as dart tagging via manned submersible, underwater surgical implantation, and the ingestion of baited transmitters have facilitated the monitoring of species that can not survive being brought to the surface, while modified capture, tag, and release approaches have been used for species that can withstand depressurization. These tracking data have revealed patterns in the vertical and horizontal movement behaviours and population connectivity of a number of data deficient species, as well as contributing to management by allowing the effectiveness of reserves, fisheries management boundaries, and fishery closures to be evaluated. With the rapid expansion of fisheries and natural resource exploration to depths beyond the continental shelf, further monitoring of deep-sea habitats and species is essential. By examining these substantial breakthroughs in biotelemetry application, in addition to the range of cutting-edge technologies that could be adapted for use in deep water, we strive to promote the timely advancement of this research in the deep sea. Further diversification of these tools and techniques will be necessary to expand the accessibility of this field to the broader scientific community.
... Future studies using telemetry data to assess bycatch risk for vertically active predators may be more effective if these extremes are considered primary at-risk depths along with core vertical distributions. The data here also demonstrate the utility of PSATs on deep-sea benthic fauna, incentivizing further development of methods to accommodate the challenges of tracking these species (Edwards et al. 2019a). For example, satellite tracking of Patagonian toothfish Dissostichus eleginoides in the South Atlantic and big skate Beringraja binoculata in the Gulf of Alaska revealed movement dynamics and seasonal depth distributions that were previously undescribed (Brown et al. 2013, Farrugia et al. 2016. ...
... For example, satellite tracking of Patagonian toothfish Dissostichus eleginoides in the South Atlantic and big skate Beringraja binoculata in the Gulf of Alaska revealed movement dynamics and seasonal depth distributions that were previously undescribed (Brown et al. 2013, Farrugia et al. 2016. Tracking studies for deep-sea species have been relatively rare thus far (Edwards et al. 2019a), despite the global distribution of deep-sea fisheries ) and marked species declines in associated deep-sea fauna (Devine et al. 2006). These data limitations underscore the value of improved biological information for datadeficient benthopelagic species. ...
Greenland halibut Reinhardtius hippoglossoides are bottom-dwelling flatfish that support commercial and community fisheries in Baffin Bay, Canada. Recently, exploratory inshore summer fisheries have raised concerns surrounding the bycatch of Greenland sharks Somniosus microcephalus and Arctic skate Amblyraja hyperborea , which are susceptible to overfishing due to their conservative life history traits. To explore fisheries selectivity and opportunities for bycatch mitigation, we combined pop-up satellite archival tags (PSATs) and fisheries data to assess habitat overlap and catch trends across these 3 species. PSAT data showed variable inter-specific overlap, with Greenland sharks primarily inhabiting depths <1000 m (725 ± 193 m), Greenland halibut inhabiting a narrower depth range (1030 ± 113 m), and Arctic skates overlapping depths (950 ± 225 m) of both species. However, fisheries data suggested high inter-specific overlap at deepest depths, with peak catch-per-unit-effort (CPUE) of all species at depths 800-1000 m. A marked decline in Greenland shark CPUE was observed throughout the fishing season which was best explained by cumulative fishing pressure. Combined tagging and fisheries data suggest that targeting specific seasonal habitat will not decrease bycatch, and inshore summer longline fisheries should be evaluated in the context of potentially high elasmobranch mortality, with enforced bycatch handling practices and alternative mitigation measures (e.g. gear modification or reduced soak times) required.
... The importance of long-term datasets for assessing potential behavioural modification and maximising the output of telemetry studies A unique aspect of our multiyear tracking dataset was that it allowed the comparison of the movement behaviours exhibited by sharks immediately following tagging with those displayed by the same individuals in subsequent years upon returning to the system. The potential for capture-induced stress to modify animal behaviours recorded post-tagging is a known consideration for telemetry studies and is of particular concern for deep-water species such as the Greenland shark that must be brought to the surface for tagging and, as such, are likely to experience acute changes in ambient temperature and pressure (Edwards et al. 2019a). Post-release behavioural modifications have been documented in a number of tagged species including sea birds (Phillips et al. 2003), pelagic teleosts (Abascal et al. 2010;Hoolihan 2005), and sharks (Campana et al. 2009;Hoolihan et al. 2011;Nakano et al. 2003), resulting in concern over the reliability of tagging records in providing accurate representations of naturally occurring animal behaviours. ...
... Little is known about the navigational cues used by deep-water species to orient movements through environmental landscapes at a finer spatial scale. This is likely due to the current lack of telemetry technologies rated for use in deep-water that provide both fine-scale movement data and simultaneous records of environmental conditions (e.g., depth and temperature; Edwards et al. 2019a). Of the limited fine-scale movement records available for deep-water species, very few have reported the identification of navigational cues. ...
As Arctic ecosystems become increasingly vulnerable to climate- and human-induced stressors, effective marine management will rely on the characterization of fish movements. Over a six-year study period, the movements of 65 Greenland sharks (Somniosus microcephalus) (41 males, 24 females [mean LT = 2.48 ± 0.50 m]) were monitored using static acoustic telemetry. Shark presence in a typical deep-water fjord was restricted to the summer open-water period. Residency duration varied based on age-class (juvenile [n=17] vs. subadult [n=48]), however, activity space size and extent were comparable. A quarter of tagged sharks (n=16) returned to the system in subsequent years after tagging, with individuals re-detected for a maximum of 4 y. Movements between coastal and offshore waters occurred primarily via a deep-water channel with sharks detected along the channel banks. These multi-year data depict how a potentially vulnerable Arctic predator utilizes a deep-water fjord in the context of the regional development of community inshore and offshore commercial fisheries.
... Although this technology has proven useful for behavioral tracking in shallow water scenarios (14), its performance has not yet been fully examined in the deep sea. Only a few efforts have been conducted to follow populations movements over kilometer scales (15) with acoustic receivers mounted on moored of curtain or gate typologies (16). ...
... platforms has been crucial, which can substantially boost traditional tracking methods [e.g., (15,16)] and extend target tracking beyond the limits of current LBL systems. In doing so, we have worked with two methods for target localization, which have been used in combination to extend their capabilities: (i) through static receivers anchored on the seabed and using TDOA algorithms, where 1-m resolution can be achieved, and (ii) using a single receiver installed on an underwater vehicle for dynamic tracking using the AOTT algorithm, which is capable of localizing and tracking acoustic tags only by ping detections. ...
Knowing the displacement capacity and mobility patterns of industrially exploited (i.e., fished) marine resources is key to establishing effective conservation management strategies in human-impacted marine ecosystems. Acquiring accurate behavioral information of deep-sea fished ecosystems is necessary to establish the sizes of marine protected areas within the framework of large international societal programs (e.g., European Community H2020, as part of the Blue Growth economic strategy). However, such information is currently scarce, and high-frequency and prolonged data collection is rarely available. Here, we report the implementation of autonomous underwater vehicles and remotely operated vehicles as an aid for acoustic long-baseline localization systems for autonomous tracking of Norway lobster (Nephrops norvegicus), one of the key living resources exploited in European waters. In combination with seafloor moored acoustic receivers, we detected and tracked the movements of 33 tagged lobsters at 400-m depth for more than 3 months. We also identified the best procedures to localize both the acoustic receivers and the tagged lobsters, based on algorithms designed for off-the-shelf acoustic tags identification. Autonomous mobile platforms that deliver data on animal behavior beyond traditional fixed platform capabilities represent an advance for prolonged, in situ monitoring of deep-sea benthic animal behavior at meter spatial scales.
... The application of various analyses (e.g. network analysis, home range, residency and site-fidelity indices) to acoustic detection data [2,[11][12][13][14][15] has proved valuable in the assessment of individual movement patterns of different species [16,17]. ...
Understanding how reef-associated sharks use coastal waters through their ontogeny is important for their effective conservation and management. This study used the horizontal movements of acoustically tagged Caribbean reef sharks ( Carcharhinus perezi ) to examine their use of coastal space around the Cayman Islands between 2009 and 2019. A total of 39 (59.1%) tagged sharks (male = 22, female = 17, immature = 18, mature = 21) were detected on the islands wide network of acoustic receivers. The detection data were used to calculate values of Residency Index (RI), Site-Fidelity Index (SFI) and minimum linear displacement (MLD), as well as for network analysis of individual shark movements to test for differences between demographics, seasons, and diel periods. Sharks were detected for up to 1,598 days post-tagging and some individuals showed resident behaviour but the majority of tagged individuals appear to have been one-off or only occasional transient visitors to the area. Generally, individuals showed strong site-fidelity to different areas displaying linear home ranges of < 20 km. The evidence indicates that there was no pattern of diel behaviour. Tagged sharks generally showed increased movements within and between islands during the summer (April–September), which may be related to breeding activity. Some individuals even made occasional excursions across 110 km of open water > 2,000 m deep between Grand Cayman and Little Cayman. One mature female shark showed a displacement of 148.21 km, the greatest distance reported for this species. The data shows that the distances over which some sharks moved, greatly exceeded the extent of any one of the islands’ marine protected areas indicating that this species may be more mobile and dispersive than previously thought. This study provides support for the blanket protection to all sharks throughout Cayman waters, which was incorporated within the National Conservation Act in 2015.
... Stand-alone systems (i.e., landers) prone to temporal intermittent deployments have been utilized to get around these restrictions. For instance, some examples are the installation of moored instruments to track animals with tags [6] or the development of the EMSO Generic Instrument Module (EGIM), which was designed for stand-alone applications [7]. ...
... Research on extreme-environment organisms started with diving in deep-sea habitats to discover novel communities of organisms. Large-scale survey, especially mapping at the deep-sea floor, makes in-depth studies of the mysteries of hidden communities that thrive in the deep sea [46]. Surveying has difficulties in getting long-term dynamic information. ...
Deep-sea environment, characterized by high pressures, extremely high/low temperatures, limited photosynthesis-generated organic matter, darkness, and high levels of corrosion, is home to flourishing special ecosystems in the world. Here, we illustrate how the deep-sea equipment offers insights into the study of life in the deep sea based on the work in the past five decades. We first describe how organisms in the deep sea are studied, even though it is highly difficult to get access to such extreme environments. We then explain the role of deep-sea technologies in advancing research on the evolution of organisms in hydrothermal vents, cold seeps, seamounts, oceanic trenches, and whale falls from the following perspectives: biological diversity, mechanisms of environmental adaptation, biological evolution, and ecosystem connectivity. Finally, to better understand the function and service of deep-sea organisms, and further conserve the special creatures under anthropologic activity and climate change, we highlighted the importance of innovative deep-sea technologies to promote cutting-edge research on deep-sea organisms, and noted the remaining challenges and developing directions for deep-sea equipment.
... Limited by equipment and technology, the development of the human understanding of the deep sea was quite slow until the last century. After more than 150 years of deep-sea exploration, scientists have gradually revealed the mystery of the special life system that thrives in the deep sea (Edwards et al., 2019). ...
The deep-sea environment creates the largest ecosystem in the world with the largest biological community and extensive undiscovered biodiversity. Nevertheless, these ecosystems are far from well known. Deep-sea equipment is an indispensable approach to research the life in extreme environments in the deep-sea environment due to the difficulty in obtaining access to these unique habitats. This work reviewed the historical development and the state-of-the-art of deep-sea equipment suitable for researching extreme ecosystems, to clarify the role of this equipment as a promoter for the progress of life in extreme environmental studies. Linkages of the developed deep-sea equipment and the discovered species are analyzed in this study. In addition, Equipment associated with researching the deep-sea ecosystems of hydrothermal vents, cold seeps, whale falls, seamounts and oceanic trenches are introduced and analyzed in detail. To clarify the thrust and key points of the future promotion of life in extreme environmental studies, prospects and challenges related to observing equipment, samplers, laboratory simulation systems, and submersibles are proposed. Furthermore, a blueprint for the integration of in situ observations, sampling, controllable culture, manned experiments in underwater environments, and laboratory simulations is depicted for future studies.
... 66 Battery-powered tags are attached to a subset of fish within a group and data from these tags are directed to an acoustic receiver via hydro-acoustic signals. 178 Acoustic telemetry has been investigated for its feasibility in monitoring fish swimming activity in aquaculture settings. 46,[179][180][181][182][183] Receivers are generally submerged near or within the fish tank/cage to capture and interpret received signals into usable data, which are then stored internally or uploaded into a wireless database. ...
As aquaculture continues to grow and intensify, there is an increasing public concern over the welfare of farmed fish. Stress and production-related pathologies and repressed growth are examples of the challenges facing aquaculture, and their impacts could be minimised by effective identification of the early signs of impaired welfare. Many welfare monitoring methods have been recommended; however, continuous and reliable welfare monitoring in aquaculture is not yet widespread and commonplace. The aim of this scoping review was to present an overview of the most recent developments in fish welfare assessments with a specific focus on practical translation to the aquaculture industry. A keyword-based search was undertaken to identify peer-reviewed papers published between 2014 and 2020 in which a novel method with the potential to be used for the assessment of fish welfare in aquaculture was introduced. The results were sorted into two categories: non-invasive and invasive methods. All methods were assessed for their advantages and disadvantages, potential applicability to aquaculture. Invasive methods were also ranked on their degree of impact. It is concluded that increased interest into fish welfare, in combination with more intelligent modern technology, has resulted in the development of newer and more refined alternatives to traditional methods of welfare assessment such as behaviour monitoring by 2D cameras and plasma cortisol evaluation. Although, in many cases, more research is needed before these methods are suitable for widespread industry use, studies that focus on increasing the precision, automation and practical applicability of these methods are a promising avenue for future research.
... For this purpose, miniaturised off-the-shelf tags are usually chosen for many studies [5]. For example, the V7 series from Vemco/Innovasea (Nova Scotia, Canada) or the IBT series from Sonotronics (Arizona, USA). ...
... Pingers that can be used in deep-sea areas below 5000 m are available [41]. Therefore, for deep-sea mapping which has been difficult to do by conventional methods, in the future, it would be possible to use this method with deep-sea creatures. ...
Creation of a seabed map is a significant task for various activities including safe navigation of vessels, commercial fishing and securing sea-mined resources. Conventionally, search machines including autonomous underwater vehicles or sonar systems have been used for this purpose. Here, we propose a completely different approach to improve the seabed map by using benthic (sting and electric) rays as agents which may explore the seabed by their autonomous behavior without precise control and possibly add extra information such as biota. For the first step to realize this concept, the detail behavior of the benthic rays must be analyzed. In this study, we used a system with a large water tank (10 m × 5 m × 6 m height) to measure the movement patterns of the benthic rays. We confirmed that it was feasible to optically trace the 2D and 3D movement of a sting and an electric ray and that the speed of the rays indicated whether they were skimming slowly over the bottom surface or swimming. Then, we investigated feasibility for measuring the sea bottom features using two electric rays equipped with small pingers (acoustic transmitters) and receivers on a boat. We confirmed tracing of the movements of the rays over the sea bottom for more than 90 min at 1 s time resolution. Since we can know whether rays are skimming slowly over the bottom surface or swimming in water from the speed, this would be applicable to mapping the sea bottom depth. This is the first step to investigate the feasibility of mapping the seabed using a benthic creature.
Acoustic telemetry (AT) has become ubiquitous in aquatic monitoring and fish biology, conservation and management. Since the early use of active ultrasonic tracking that required researchers to follow at a distance their species of interest, the field has diversified considerably with exciting advances in both hydrophone and transmitter technology. Once a highly specialised methodology however, AT is fast becoming a generalist tool for those wishing study or conserve fishes, leading to diversifying application by non-specialists. With this transition in mind, we evaluate exactly what AT has become useful for, discussing how the technological and analytical advances around AT can address important questions within fish biology. In doing so, we highlight the key ecological and applied research areas where AT continues to reveal crucial new insight, and in particular, when combined with complimentary research approaches. We aim to provide a comprehensive breakdown of the state of the art for the field of AT, discussing the ongoing challenges, where its strengths lie, and how future developments may revolutionise fisheries management, behavioural ecology and species protection. Through selected papers we illustrate specific applications across the broad spectrum of fish biology. By bringing together the recent and future developments in this field under categories designed to broadly capture many aspects of fish biology, we hope to offer a useful guide for the non-specialist practitioner as they attempt to navigate the dizzying array of considerations and ongoing developments within this diverse toolkit.
Common marine spatial planning challenges include lack of data on the marine environment, high mobility of both animals and humans, and plan implementation challenges including lack enforcement and compliance with regulations along with monitoring deficiencies. These can be potentially addressed using geospatial technologies (GTs) such as remote sensing, GPS and GIS. This research presents geospatial tools that are available for the process of developing, implementing, and monitoring marine spatial plans. Tools include satellites and water-based platforms carrying various sensors and receivers for environmental ocean data, vessel tracking and animal telemetry via multispectral, acoustic, radar, and other means. Planners and ocean managers might not always be aware of technological solutions available for the development and implementation of marine spatial plans. Here, urgent planning needs, summarized from various publications, are linked to GTs solutions published in relevant literature between the years 2015–2020. The GTs were used for data collection, dynamic human activities’ management, environmental monitoring and enforcement, all as required by marine spatial plans. This paper concludes with insights into GT solutions that can enhance the process of evidence-based management and spatial planning in marine environments.
This review assesses the feasibility of a deepwater shark tagging programme in New Zealand waters. Firstly, it provides a general overview of current knowledge on deepwater shark age and growth, movement and habitat use, and post-release survival. Secondly, the report discusses tagging study designs and application. Lastly, an assessment gives options for a deepwater shark tagging programme in New Zealand.
Knowledge on movement patterns within marine fish has important implications for population biology and management. Many deep-sea fish species possess complex life-history patterns with distributions occurring across vast areas. The nature of connectivity at different life-history stages in a dynamic Patagonian toothfish population on the Patagonian Shelf, Slope and deep-sea plateau around the Falkland Islands remains speculative. A five plus year tag-recapture program was executed to elucidate the movement patterns as well as the extent that these are driving connectivity during the adult life-history stages in the region. Tagging and recapture results indicated that the majority of individuals (77.59%) displayed high levels of site fidelity (<50 km), suggesting that seasonal spawning migrations are unlikely. However, 9.91% of individuals undertook large-distance movements across oceanographic and physical boundaries. These were characterised by large (>120 cm) fish inhabiting the slope and deep-sea plains (north of 52°S) undertaking southward (direction = 150-240°) home-range relocations to spawning areas on the Burdwood Bank, North Scotia Ridge and southern Chile. The results provide compelling evidence to a single Patagonian toothfish metapopulation, with important considerations in terms of the spawning stock dynamics, and the development of regional management agreements across their Patagonian distribution.
Long-distance migrations by marine vertebrates are often triggered by pronounced environmental cues. For the endangered basking shark (Cetorhinus maximus), seasonal changes in water temperature are frequently proposed as a cue for aggregation within (and dispersal from) coastal hotspots. The inference is that such movements reflect year-round occupancy within a given thermal ‘envelope’. However, the marked variance in timing, direction and depth of dispersal movements hint at a more nuanced explanation for basking sharks. Here, using data from pop-off archival transmitters deployed on individuals in Irish waters, we explored whether autumnal decreases in water temperature triggered departure from coastal habitats and how depth and location shaped the sharks’ realised thermal environment over time. Temperature was not an apparent driver of dispersal from coastal seas, and variance in daily temperature ranges reflected occupancy of different habitats; coastal mixed/stratified and offshore subtropical/tropical waters. Furthermore, individuals that moved offshore and into more southern latitudes off Africa, exhibited a distinct daily cycle of deep dives (00:00–12:00, 200 m–700 m; 12:00–00:00, 0–300 m), experiencing a more extreme range of temperatures (6.8–27.4 °C), including cooler minimum temperatures, than those remaining in European coastal habitat (9.2–17.6 °C). Collectively, these findings challenge the supposition that temperature serves as a universal driver of seasonal dispersal from coastal seas and prompts further studies of deep-water forays in offshore areas.
Biological structures are inherently complex in nature. Structural hierarchy, chemical anisotropy, and compositional heterogeneity are ubiquitous in biological systems and play a key role in the functionality of living systems. For decades, methods such as soft lithography have enabled recreation of such arrangements through precise spatial control of molecular patterns in 2D. With technological advances and increasing understanding of molecular and structural biology, there has been an increasing interest in recreating such spatial organizations in 3D. In this review, a comprehensive summary of the latest technologies being used to create 3D patterns of functional molecules within hydrogels for tissue engineering applications is presented. The review is divided into five groups of technologies defined according to the main driving force used to fabricate the patterns including light, precise chemical design, microfluidics, 3D printing, and non‐contact forces (i.e. electric, magnetic, or acoustic fields and self‐assembly).
The technological advances of the last twenty years have brought huge advances in our understanding of the deep sea and of the species inhabiting this elusive and fascinating environment. Synthesising the very latest research and discoveries, this is a comprehensive and much-needed account of deep-sea fishes. Priede examines all aspects of this incredibly diverse group of animals, reviewing almost 3,500 species and covering deep-sea fish evolution, physiology and ecology as well as charting the history of their discovery from the eighteenth century to the present day. Providing a global account of both pelagic and demersal species, the book ultimately considers the effect of the growing deep-sea fishing industry on sustainability. Copiously illustrated with explanations of the deep-sea environment, drawings of fishes and information on how they adapt to the deep, this is an essential resource for biologists, conservationists, fishery managers and anyone interested in marine evolution and natural history.
Baited remote underwater video cameras were deployed in the Eastern Canadian Arctic, for the purpose of estimating local densities of the long-lived Greenland shark within five deep-water, data-poor regions of interest for fisheries development and marine conservation in Nunavut, Canada. A total of 31 camera deployments occurred between July-September in 2015 and 2016 during joint exploratory fishing and scientific cruises. Greenland sharks appeared at 80% of deployments. A total of 142 individuals were identified and no individuals were observed in more than one deployment. Estimates of Greenland shark abundance and biomass were calculated from averaged times of first arrival, video-derived swimming speed and length data, and local current speed estimates. Density estimates varied 1-15 fold among regions; being highest in warmer (>0 °C), deeper areas and lowest in shallow, sub-zero temperature regions. These baited camera results illustrate the ubiquity of this elusive species and suggest that Nunavut's Lancaster Sound eco-zone may be of particular importance for Greenland shark, a potentially vulnerable Arctic species.
Globally, small‐scale inshore fisheries are being recognized as highly beneficial for underdeveloped coastal communities since they directly contribute to local economies. Community coastal fisheries, however, may target species that are simultaneously harvested by large commercial vessels in adjacent offshore waters, creating uncertainty over stock units and connectivity that complicate management.
Greenland halibut Reinhardtius hippoglossoides , a commercially important flatfish species in the Arctic, were tagged in Scott Inlet, coastal Baffin Island, Canada, with acoustic transmitters and tracked for a 1‐year period. Our aim was to measure fish movement and connectivity between inshore habitats, where Inuit fisheries are developing, and offshore waters, where an established commercial fishery operates. Four movement metrics were established, and cluster analysis and a mixed effects model were used to define movement types and identify environmental covariates of the presence/absence within the coastal environment respectively.
Two distinct movement patterns were characterized for Greenland halibut; the majority were transients that were no longer detected inshore by the end of November ( n = 47, 72%), and a smaller group of intermittently resident fish that moved into the offshore at the same time as transient fish, but returned to the coastal environment in the winter ( n = 8, 12%), with the remainder being undefined. The presence of Greenland halibut in the inshore was negatively correlated with ice cover, indicating that fish moved offshore as sea ice formed.
Synthesis and applications . Greenland halibut were previously thought to be highly resident within the coastal environment of Baffin Bay; however, our data demonstrates that this is not true for all areas. In Scott Inlet and adjacent coastal regions, Greenland halibut exhibit complex inshore‐offshore connectivity, suggesting inshore and offshore fisheries require a shared quota. We recommend that in the face of developing global small‐scale coastal fisheries, improved understanding of stock connectivity between environments is required to sustainably manage commercial fish species.
Many Atlantic Salmon Salmo salar populations within the southern extent of the species’ range are at critically low abundances, while others have been extirpated. The focus of many ongoing recovery efforts is on maximizing the number of smolts that reach the ocean, where marine survival is low, primarily through hatchery supplementation and improvement of in-river hydropower system management. However, estuaries also are known to be sites of high mortality, although in many cases the correlates of this mortality are poorly characterized. We acoustically tagged hatchery smolts (n = 666) during 2001–2005 to evaluate migration performance through freshwater, estuarine, and bay reaches of the small but tidally dynamic Dennys River, Maine, USA, to investigate potential drivers contributing to low returns within the system. Migration behaviors (e.g., migration timing and tidal use) were typical for Atlantic Salmon smolts, but reversals during migration were observed upon entry into the estuary environment more frequently in this system than in regional rivers. We used Cormack–Jolly–Seber mark–recapture models to estimate apparent survival within the study environment during this period. We found two distinct periods of survival, with much lower survival in 2003–2005 than in 2001 and 2002 (more than a 40% decrease). Among the variables considered, temperature and migratory behavior had the largest effects on survival. We found that survival increased by about 28% across the range of temperatures observed during these years; additionally, survival increased by about 15% for fish that reversed direction during migration compared to fish that did not. These results indicate that extreme environmental changes during the transition through this coastal system constitute a significant obstacle to Atlantic Salmon restoration stocking efforts.
Received March 30, 2017; accepted August 7, 2017
Pacific halibut Hippoglossus stenolepis (Schmidt) is presently considered to consist of a single spawning population extending from California through the Bering Sea. However, this satellite tagging investigation suggests that geographic landforms and discontinuities in the continental shelf appear to limit the interchange of mature Pacific halibut among large marine ecosystems and delineate the boundaries of potential spawning components in the Gulf of Alaska and Bering Sea, with smaller components along the Aleutian Islands. The geographic segregation of these spawning components may be reinforced by regional behavioural adaptations and different temperature regimes in each area. These results suggest that the Pacific halibut population may be segregated into somewhat discrete spawning units among which less mixing is likely than that which occurs within them. As such, future stock assessment metrics may be most effective in preserving population function if spawning ecology is treated as a basin-scale process.
Acoustic telemetry is the primary method to actively track aquatic animals for behavioral studies. However, the small storage capacities of the batteries used in the transmitters limit the time that the implanted animals can be studied. In this research, we developed and implemented a battery-free acoustic transmitter that uses a flexible piezoelectric beam to harvest energy from fish swimming as the power source. The transmitter sends out a unique identification code with a sufficiently strong signal (150 dB, ref: 1 μPa at 1 meter) that has a detection range of up to 100 meters. Two prototypes, 100 mm and 77 mm long, respectively, weighing only about 1 gram or less in air, were sub-dermally implanted in two species of live fish. Transmissions were successfully detected as the fish swam in a natural manner. This represents the first known implanted energy-harvesting transmitter demonstrated in vivo. Successful development of this transmitter greatly expands the potential for long-term studies of the behaviors of aquatic animals and for subsequently developing strategies to mitigate the environmental impacts of renewable energy systems.
The deep sea, the largest biome on Earth, has a series of characteristics that make this environment both distinct from other marine and land ecosystems and unique for the entire planet. This review describes these patterns and processes, from geological settings to biological processes, biodiversity and biogeographical patterns. It concludes with a brief discussion of current threats from anthropogenic activities to deep-sea habitats and their fauna.
Investigations of deep-sea habitats and their fauna began in the late 19th century. In the intervening years, technological developments and stimulating discoveries have promoted deep-sea research and changed our way of understanding life on the planet. Nevertheless, the deep sea is still mostly unknown and current discovery rates of both habitats and species remain high. The geological, physical and geochemical settings of the deep-sea floor and the water column form a series of different habitats with unique characteristics that support specific faunal communities. Since 1840, 28 new habitats/ecosystems have been discovered from the shelf break to the deep trenches and discoveries of new habitats are still happening in the early 21st century. However, for most of these habitats the global area covered is unknown or has been only very roughly estimated; an even smaller – indeed, minimal – proportion has actually been sampled and investigated. We currently perceive most of the deep-sea ecosystems as heterotrophic, depending ultimately on the flux on organic matter produced in the overlying surface ocean through photosynthesis. The resulting strong food limitation thus shapes deep-sea biota and communities, with exceptions only in reducing ecosystems such as inter alia hydrothermal vents or cold seeps. Here, chemoautolithotrophic bacteria play the role of primary producers fuelled by chemical energy sources rather than sunlight. Other ecosystems, such as seamounts, canyons or cold-water corals have an increased productivity through specific physical processes, such as topographic modification of currents and enhanced transport of particles and detrital matter. Because of its unique abiotic attributes, the deep sea hosts a specialized fauna. Although there are no phyla unique to deep waters, at lower taxonomic levels the composition of the fauna is distinct from that found in the upper ocean. Amongst other characteristic patterns, deep-sea species may exhibit either gigantism or dwarfism, related to the decrease in food availability with depth. Food limitation on the seafloor and water column is also reflected in the trophic structure of heterotrophic deep-sea communities, which are adapted to low energy availability. In most of these heterotrophic habitats, the dominant megafauna is composed of detritivores, while filter feeders are abundant in habitats with hard substrata (e.g. mid-ocean ridges, seamounts, canyon walls and coral reefs). Chemoautotrophy through symbiotic relationships is dominant in reducing habitats.
Deep-sea biodiversity is among of the highest on the planet, mainly composed of macro and meiofauna, with high evenness. This is true for most of the continental margins and abyssal plains with hot spots of diversity such as seamounts or cold-water corals. However, in some ecosystems with particularly "extreme" physicochemical processes (e.g. hydrothermal vents), biodiversity is low but abundance and biomass are high and the communities are dominated by a few species. Two large-scale diversity patterns have been discussed for deep-sea benthic communities. First, a unimodal relationship between diversity and depth is observed, with a peak at intermediate depths (2000–3000 m), although this is not universal and particular abiotic processes can modify the trend. Secondly, a poleward trend of decreasing diversity has been discussed, but this remains controversial and studies with larger and more robust data sets are needed. Because of the paucity in our knowledge of habitat coverage and species composition, biogeographic studies are mostly based on regional data or on specific taxonomic groups. Recently, global biogeographic provinces for the pelagic and benthic deep ocean have been described, using environmental and, where data were available, taxonomic information. This classification described 30 pelagic provinces and 38 benthic provinces divided into 4 depth ranges, as well as 10 hydrothermal vent provinces. One of the major issues faced by deep-sea biodiversity and biogeographical studies is related to the high number of species new to science that are collected regularly, together with the slow description rates for these new species. Taxonomic coordination at the global scale is particularly difficult, but is essential if we are to analyse large diversity and biogeographic trends. <br.
Because of their remoteness, anthropogenic impacts on deep-sea ecosystems have not been addressed very thoroughly until recently. The depletion of biological and mineral resources on land and in shallow waters, coupled with technological developments, are promoting the increased interest in services provided by deep-water resources. Although often largely unknown, evidence for the effects of human activities in deep-water ecosystems – such as deep-sea mining, hydrocarbon exploration and exploitation, fishing, dumping and littering – is already accumulating. Because of our limited knowledge of deep-sea biodiversity and ecosystem functioning and because of the specific life-history adaptations of many deep-sea species (e.g. slow growth and delayed maturity), it is essential that the scientific community works closely with industry, conservation organisations and policy makers to develop robust and efficient conservation and management options.
In August and September of 1997 and 1998, we used SCUBA techniques to surgically implant Vemco V16 series acoustic transmitters in 6 greenspotted rockfish (Sebastes chlorostictus) and 16 bocaccio (S. paucispinis) on the flank of Soquel Canyon in Monterey Bay, California. Fish were captured at depths of 100-200 m and reeled up to a depth of approximately 20 m, where a team of SCUBA divers anesthetized and surgically implanted acoustic transmitters in them. Tagged fish were released on the seafloor at the location of catch. An array of recording receivers on the seafloor enabled the tracking of horizontal and vertical fish movements for a three-month period. Greenspotted rockfish tagged in 1997 exhibited almost no vertical movement and showed limited horizontal movement. Two of these tagged fish spent more than 90% of the time in a 0.58-km2 area. Three other tagged greenspotted rockfish spent more than 60% of the time in a 1.6-km2 area but displayed frequent horizontal movements of at least 3 km. Bocaccio exhibited somewhat greater movements. Of the 16 bocaccio tagged in 1998, 10 spent less than 10% of the time in the approximately 12-km2 study area. One fish stayed in the study area for about 50% of the study time. Signals from the remaining 5 fish were recorded in the study area the entire time. Bocaccio frequently moved vertically 10-20 m and occasionally displayed vertical movements of 100 m or greater.
Estimated declines in shark and ray populations worldwide have raised major, widespread concern about the impacts of global fisheries on elasmobranchs. The mechanisms causing elasmobranch mortality during fisheries’ capture are not fully understood, but we must gain greater clarity on this topic for fisheries managers to develop effective conservation plans to mitigate further population declines. To evaluate how two important factors, respiratory mode and fishing gear type, impact elasmobranch survival, we compiled publicly available data sources on the immediate mortality percentages of 83 species and post-release mortality percentages of 40 species. Using Bayesian models, we found that sharks and rays captured in longlines had significantly lower immediate mortality than those caught in trawls or gillnets. Our models also predicted the mean total discard mortality (combined immediate and post-release mortality) percentages of obligate ram-ventilating elasmobranchs caught in longline, gillnet and trawl gear types to be 49.8, 79.0 and 84.2%, respectively. In contrast, total discard mortality percentages of stationary-respiring species were significantly lower (longline capture mean = 7.2%, gillnet capture mean = 25.3%, trawl capture mean = 41.9%). Our global meta-analysis provides the first quantified demonstration of how mortality is affected by these two factors across a broad range of species. Our results and approach can be applied to data-deficient elasmobranchs and fisheries to identify species that are likely to experience high rates of mortality due to respiratory mode and/or fishing methods used, so that appropriate mitigation measures can be prioritized and investigated.
Substantial advances have been made in our understanding of the movement of species, including processes such as dispersal and migration. This knowledge has the potential to improve decisions about biodiversity policy and management, but it can be difficult for decision makers to readily access and integrate the growing body of movement science. This is, in part, due to a lack of synthesis of information that is sufficiently contextualized for a policy audience. Here, we identify key species movement concepts, including mechanisms, types, and moderators of movement, and review their relevance to (1) national biodiversity policies and strategies, (2) reserve planning and management, (3) threatened species protection and recovery, (4) impact and risk assessments, and (5) the prioritization of restoration actions. Based on the review, and considering recent developments in movement ecology, we provide a new framework that draws links between aspects of movement knowledge that are likely the most relevant to each biodiversity policy category. Our framework also shows that there is substantial opportunity for collaboration between researchers and government decision makers in the use of movement science to promote positive biodiversity outcomes.
The deep-water flatfish Greenland halibut Reinhardtius hippoglossoides (Walbaum) is common along the West Greenland coast. In the northwestern fjords, Greenland halibut is an important socio-economic resource for the Greenland community, but due to the deep and partly ice-covered environment, very little is known about its behavior and habitat characteristics. We tagged adult Greenland halibut in the waters off Ilulissat with electronic data storage tags that collected information on depth, temperature, and time. Although clear differences between individuals in migration and vertical behavior were present, we discovered a consistent seasonal migration from the relatively shallow-water Disko Bay area into the deep waters of the Ilulissat Icefjord, where the fish resided in the winter months before returning to Disko Bay. Vertical activity was pronounced at both locations, with fish covering vertical distances of up to 100 m within 15 min. During the winter months, the fish experienced temperatures between ca. 0 and 4 degrees C, with most experiencing temperatures of 2 to 3 degrees C. Irrespective of year and quarter of the year, the fish experienced warmer water and a broader range of temperatures when resident in Disko Bay (mean range 2.6 degrees C) than when resident in the ice fjord (mean range 1.4 degrees C). Using the tagged halibut as a 'live tool,' we show that parts of the ice fjord are hundreds of meters deeper than previously thought. We also document the first seawater temperature measurements made beneath the Jakobshavn Isbrae outlet glacier, revealing a positive relationship between depth and temperature for the upper 600 m and a between-year variation in temperatures beneath the ice sheet in 2001, 2002, and 2003.
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.
Copyright © 2015, American Association for the Advancement of Science.
Loher, T. 2011. Analysis of match–mismatch between commercial fishing periods and spawning ecology of Pacific halibut (Hippoglossus stenolepis), based on winter surveys and behavioural data from electronic archival tags. – ICES Journal of Marine Science, 68: 2240–2251.
The fishery for halibut (Hippoglossus stenolepis) in the eastern Pacific is closed during the boreal winter, roughly corresponding to the seasonal spawning of the species. Opening and closing dates for each season are stipulated annually based on economics and biology. Historical surveys and data from electronic tags are analysed to assess the extent to which recent closures have encompassed the annual spawning cycle of the species, as defined by migration to offshore spawning sites, active spawning, and return to feeding areas. These were assessed by calculating mean maximum daily depth profiles for fish exhibiting seasonal migration, calculating the date-specific proportions of the tagged population either migrating to or resident on their feeding or spawning grounds, and examining the temporal distribution of spent and running fish in historical surveys along with evidence of spawning contained in high-resolution tag data. The data indicate that fishery closures over the past 20 years have been consistently too short to protect the entirety of a migration period that begins as early as September and is not substantially completed until May. Additionally, some recent season openings have encroached on the active spawning season. Failure to fully protect spawning migrations may allow seasonal interception fisheries, and the selective removal of early and late spawners could cause changes in stock demographics, restrict effective spawning, and influence long-term stock productivity, especially in the face of environmental variability.
Currently, it is assumed that eastern Pacific halibut Hippoglossus stenolepis belong to a single, fully mixed population extending from California through the Bering Sea, in which adult halibut disperse randomly throughout their range during their lifetime. However, we hypothesize that halibut dispersal is more complex than currently assumed and is not spatially random. To test this hypo thesis, we studied the seasonal dispersal and behavior of Pacific halibut in the Bering Sea and Aleutian Islands (BSAI). Pop-up Archival Transmitting tags attached to halibut (82 to 154 cm fork length) during the summer provided no evidence that individuals moved out of the Bering Sea and Aleutian Islands region into the Gulf of Alaska during the mid-winter spawning season, supporting the concept that this region contains a separate spawning group of adult halibut. There was evidence for geographically localized groups of halibut along the Aleutian Island chain, as all of the individuals tagged there displayed residency, with their movements possibly impeded by tidal currents in the passes between islands. Mid-winter aggregation areas of halibut are assumed to be spawning grounds, of which 2 were previously unidentified and extend the species' presumed spawning range similar to 1000 km west and similar to 600 km north of the nearest documented spawning area. If there are indeed independent spawning groups of Pacific halibut in the BSAI, their dynamics may vary sufficiently from those of the Gulf of Alaska, so that specifically accounting for their relative segregation and unique dynamics within the larger population model will be necessary for correctly predicting how these components may respond to fishing pressure and changing environmental conditions.
In 2006 the IPHC began investigating the use of ¿ shery-recaptured archival tags in order to extend its electronic tagging program to study multi-year behavior of individual halibut and behavior of ¿ sh that have traditionally been considered too small to carry Pop-up Archival Transmitting tags. The program began with a captive holding experiment designed to develop surgical techniques for internal tag implantation, and in 2009 a second holding experiment was initiated in order to investigate external tag-mounting protocols and compare them to internal tag implantation results. A total of 30 halibut in captivity at the Oregon Coast Aquarium (Newport, Oregon) were tagged with "dummy" archival tags using a variety of experimental treatments that included through-body dorsal attachment, opercular attachment oriented perpendicular to the main axis of the ¿ sh, and dart-and-tether, a treatment of intracoelomic implantation that will allow external tagging results to be directly compared to the effectiveness of surgical methods. This report provides a brief description of the methods employed, update of the status of tagged individuals, and description of new methods initiated in 2011. The 2011 methods were: 1) a modi¿ ed opercular orientation; 2) two alternative dart con¿ gurations; and 3) intramuscular implantation. Monitoring for tagging effects is ongoing and expected to continue through 2012.
Ecological connections between surface waters and the deep ocean remain poorly studied despite the high biomass of fishes and squids residing at depths beyond the euphotic zone. These animals likely support pelagic food webs containing a suite of predators that include commercially important fishes and marine mammals. Here we deploy pop-up satellite archival transmitting tags on 15 Chilean devil rays (Mobula tarapacana) in the central North Atlantic Ocean, which provide movement patterns of individuals for up to 9 months. Devil rays were considered surface dwellers but our data reveal individuals descending at speeds up to 6.0 m s(-1) to depths of almost 2,000 m and water temperatures <4 °C. The shape of the dive profiles suggests that the rays are foraging at these depths in deep scattering layers. Our results provide evidence of an important link between predators in the surface ocean and forage species occupying pelagic habitats below the euphotic zone in ocean ecosystems.
Approximately 200 km from the mouth of the Fraser River, British Columbia, Canada, adult sockeye salmon Oncorhynchus nerka, were gastrically implanted with radio transmitters without anaesthetic. Subsets of the transmitter implanted fish were also biopsied which included drawing blood from the caudal peduncle (3 ml), removal of gill tissue (0·03 g) and quantification of energetic status using a microwave fat meter. Several experiments were used to test the hypothesis that the biopsy had a negligible effect on the subsequent survival and migratory behaviour of transmitter implanted fish. In the first experiment, no difference was found in the survival (both 100%) or tag retention (both 100%) between the two treatment groups (transmitter implanted with and without biopsy) when fish were held in pens for 24 h in the marine environment. Similarly, in other experiments where fish were released to the ocean to resume their migratory journey, no statistical differences were found in the travel times of fish in the two treatment groups, or in the proportion of fish that passed in‐river telemetry checkpoints. These results indicated that the handling and biopsy methods produced similar levels of mortality and tag retention as the telemetry treatment alone and that any changes in behaviour between the two treatment groups did not adversely affect migration time. Based upon the evidence provided from the biotelemetry of >300 adult sockeye salmon, it was felt that this general type of approach could be applicable to other fish species.
Large Atlantic halibut (Hippoglossus hippoglossus) off the eastern coast of Canada were tagged with pop-up satellite archival transmission tags (N = 17) to track movements, determine ambient depth and temperature, and infer spawning activity. Many halibut showed seasonal movements from deepwater slope areas in fall and winter to shallower feeding grounds on the Scotian Shelf and Grand Banks in summer. Halibut depths ranged between 0 and 1,640 m. Mean temperature of occupation was 4.7 °C. Multiple short-term vertical ascents from a consistent baseline depth, characterized as spawning rises, were identified in seven of the tagged halibut south of the Grand Banks. All presumed spawning rises occurred in multiples of 2–6 events at 2- to 9-day intervals between October and January, spanning an average vertical extent of 50–100 m at depths of about 800–1,000 m. Given the direction and velocity of the slope water currents and the duration of the pelagic stage, the calculated 300–500 km drift of the eggs and larvae would take them onto the Scotian Shelf, as well as into the Gulf of St. Lawrence. Therefore, the location of the presumed spawning grounds is consistent with expectations based on migration compensation theory, the northeasterly migratory patterns of the juveniles, the relatively static distribution of the adults off southern Newfoundland, and the prevailing currents at depth.
Tagging mortality for Greenland halibut was studied under summer and winter conditions. The fish were caught
using longlines and tagged with a T-bar tag. The winter experiment was conducted in Cumberland Sound, Canada in
May 1997. Air temperatures were below 0°C and cold water-masses were present at 0-300m. Fish were immediately
placed in a tub of water after capture and transported by snowmobile to a heated tent for tagging and then placed in
cages that were submerged to 300m depth. The summer experiment was conducted in Upernavik, Greenland in
August 1998. Air temperatures were above 0°C but intermediate cold water-masses were present at 50-200m. In the
summer experiment fish were tagged and released in a holding tank to assess immediate tagging mortality (0 to 18h),
placed in specially designed cages and submerged to 200-500m to assess short-term tagging mortality (up to 117h). A
total of 155 Greenland halibut were included in the study. Overall tagging mortality was estimated to be 7%.
Immediate handling and tagging mortality in both the winter and summer experiments was low (<5%). Several factors
were shown to have significant effects on the outcome (level of condition). Fish held in the tanks for longer time
periods were in better condition. Moreover, females had a tendency to be in poorer condition than males immediately
following tagging. Short-term mortality was 4%. There was no difference in mortality rates between seasons. There
was no effect on mortality of the covariates size, time held in the cage and several other factors examined. However,
there was a significant correlation between the fish’s health and mortality. The study showed that tagging under
harsh winter conditions is just as possible as under summer conditions as long as exposure to sub-zero temperatures
are minimized. Our study further suggests that holding the tagged fish in an observation tank for a period of 5h or
more could reduce the tagging mortality on released fish.
Tagging mortality for Greenland halibut was studied under summer and winter conditions. The fish were caught
using longlines and tagged with a T-bar tag. The winter experiment was conducted in Cumberland Sound, Canada in
May 1997. Air temperatures were below 0°C and cold water-masses were present at 0-300m. Fish were immediately
placed in a tub of water after capture and transported by snowmobile to a heated tent for tagging and then placed in
cages that were submerged to 300m depth. The summer experiment was conducted in Upernavik, Greenland in
August 1998. Air temperatures were above 0°C but intermediate cold water-masses were present at 50-200m. In the
summer experiment fish were tagged and released in a holding tank to assess immediate tagging mortality (0 to 18h),
placed in specially designed cages and submerged to 200-500m to assess short-term tagging mortality (up to 117h). A
total of 155 Greenland halibut were included in the study. Overall tagging mortality was estimated to be 7%.
Immediate handling and tagging mortality in both the winter and summer experiments was low (<5%). Several factors
were shown to have significant effects on the outcome (level of condition). Fish held in the tanks for longer time
periods were in better condition. Moreover, females had a tendency to be in poorer condition than males immediately
following tagging. Short-term mortality was 4%. There was no difference in mortality rates between seasons. There
was no effect on mortality of the covariates size, time held in the cage and several other factors examined. However,
there was a significant correlation between the fish’s health and mortality. The study showed that tagging under
harsh winter conditions is just as possible as under summer conditions as long as exposure to sub-zero temperatures
are minimized. Our study further suggests that holding the tagged fish in an observation tank for a period of 5h or
more could reduce the tagging mortality on released fish.
It has been speculated that some deep-sea fishes can display large vertical migrations and likely doing so to explore the full suite of benthopelagic food resources, especially the pelagic organisms of the deep scattering layer (DSL). This would help explain the success of fishes residing at seamounts and the increased biodiversity found in these features of the open ocean. We combined active plus passive acoustic telemetry of blackspot seabream with in situ environmental and biological (backscattering) data collection at a seamount to verify if its behaviour is dominated by vertical movements as a response to temporal changes in environmental conditions and pelagic prey availability. We found that seabream extensively migrate up and down the water column, that these patterns are cyclic both in short-term (tidal, diel) as well as long-term (seasonal) scales, and that they partially match the availability of potential DSL prey components. Furthermore, the emerging pattern points to a more complex spatial behaviour than previously anticipated, suggesting a seasonal switch in the diel behaviour mode (benthic vs. pelagic) of seabream, which may reflect an adaptation to differences in prey availability. This study is the first to document the fine scale three-dimensional behaviour of a deep-sea fish residing at seamounts.
Atlantic halibut (Hippoglossus hippoglossus) in a Norwegian fjord were tagged with pop-up archival transmitting (PAT) tags to investigate whether they join offshore
spawning events with halibut from other regions. All fish (n = 4) remained in the fjord throughout the spawning season, suggesting that they may be reproductively segregated from other
stocks.
Interactions between animals structure food webs and regulate ecosystem function and productivity. Quantifying subsurface behavioural interactions among marine organisms is challenging, but technological advances are promoting novel opportunities.
Here, we present a framework to estimate when there is a high likelihood that aquatic animal subsurface interactions occur and test for a movement‐related behavioural response to those interactions over short temporal scales (days) using a novel multi‐sensor biologging package on a large marine predator, the Greenland shark ( Somniosus microcephalus ).
We deployed a recoverable biologging package combining a VEMCO Mobile Transceiver (VMT), accelerometer and a temperature–depth tag to quantitatively assess fine‐scale behaviour during detection events, that is when sharks carrying the novel VMT package ( animal R , n = 3) detected sharks independently tagged with transmitters in the system ( animal T , n = 29). Concurrently, we developed simulations to estimate the distances between animal R and animal T by accounting for their swim speed, the estimated detection efficiency of the VMT and the number of consecutive transmissions recorded. Accelerometer‐derived activity indices were then used as a means to test for response to potential interactions when animals are expected to be in close proximity.
Based on this approach, the three VMT‐equipped Greenland sharks exhibited higher body acceleration and greater depth changes during detections, suggesting a potential behavioural response to the presence of other sharks. A generalized additive model indicated a moderate increasing relationship in activity associated with a greater number of animal T detections.
Through the proposed framework, detection events with varying probabilities of interaction likelihoods can be derived and those data isolated and explicitly tested using acceleration data to quantify behavioural interactions. Through inputting known parameters for a species of interest, the framework presented is applicable for all aquatic taxa and can guide future study design.
Biotelemetry data have been successfully incorporated into aspects of fishery and fish habitat management; however, the processes of knowledge mobilization are rarely published in peer-reviewed literature but are valuable and of interest to conservation scientists. Here, we explore case examples from the Ocean Tracking Network (OTN), including Pacific salmon (Oncorhynchus spp.) in British Columbia, Canada; Greenland halibut (Reinhardtius hippoglossoides) in Cumberland Sound, Canada; and lemon sharks (Negaprion brevirostris) in Florida, USA, to document key processes for science integration. Typical recommendations documented in the literature (e.g., co-production of knowledge, transdisciplinary methodologies, applied research questions) were recorded to have had successful fisheries management integration, although we documented some exceptions. In each case, it was early, active, and ongoing communication outside of traditional science communication and the visual evidence of fish movement that were critical in engaging all parties with a vested interest. Networks offer forums for knowledge sharing on lessons learned and development of skills to engage in active communication. Greater investments and attention to develop these skills are needed to foster positive and active relationships that can impart real change in management and conservation.
This paper reviews the use of acoustic telemetry as a tool for addressing issues in fisheries management, and serves as the lead to the special Feature Issue of Ecological Applications titled Acoustic Telemetry and Fisheries Management. Specifically, we provide an overview of the ways in which acoustic telemetry can be used to inform issues central to the ecology, conservation, and management of exploited and/or imperiled fish species. Despite great strides in this area in recent years, there are comparatively few examples where data have been applied directly to influence fisheries management and policy. We review the literature on this issue, identify the strengths and weaknesses of work done to date, and highlight knowledge gaps and difficulties in applying empirical fish telemetry studies to fisheries policy and practice. We then highlight the key areas of management and policy addressed, as well as the challenges that needed to be overcome to do this. We conclude with a set of recommendations about how researchers can, in consultation with stock assessment scientists and managers, formulate tes-table scientific questions to address and design future studies to generate data that can be used in a meaningful way by fisheries management and conservation practitioners. We also urge the involvement of relevant stakeholders (managers, fishers, conservation societies, etc.) early on in the process (i.e., in the co-creation of research projects), so that all priority questions and issues can be addressed effectively.
Management boundaries that define populations or stocks of fish form the basis of fisheries planning. In the Arctic, decreasing sea ice extent is driving increasing fisheries development highlighting the need for ecological data to inform management. In Cumberland Sound, southwest Baffin Island, an indigenous community fishery was established in 1987 targeting Greenland halibut (Reinhardtius hippoglossoides) through the ice. Following its development, the Cumberland Sound Management Boundary (CSMB) was designated and a total allowable catch (TAC) assigned to the fishery. The CSMB was based on a sink population of Greenland halibut resident in the northern section of the Sound. Recent fishing activities south of the CSMB however, raised concerns over fish residency, the effectiveness of the CSMB and the sustainability of the community-based winter fishery. Through acoustic telemetry monitoring at depths between 400 and 1200m, and environmental and fisheries data, this study examined the movement patterns of Greenland halibut relative to the CSMB, the biotic and abiotic factors driving fish movement and the dynamics of the winter fishery. Greenland halibut undertook clear seasonal movements between the southern and northern regions of the Sound driven by temperature, dissolved oxygen and sea ice cover with most fish crossing the CSMB on an annual basis. Over the lifespan of the fishery landfast ice cover initially declined and then became variable limiting accessibility to favored fisher locations. Concomitantly, CPUE declined reflecting the effect of changing ice conditions on the location and effort of the fishery. Ultimately, these telemetry data revealed that fishers now target less productive sites outside of their favored areas and, with continued decreases in ice, the winter fishery might cease to exist. In addition, these novel telemetry data revealed that the CSMB is ineffective and led to its relocation to the entrance of the Sound in 2014. The community fishery can now develop an open-water fishery in addition to the winter fishery to exploit the TAC, which will ensure the longevity of the fishery under projected climate-change scenarios. Telemetry shows great promise as a tool for understanding deep-water species and for directly informing fisheries management of these ecosystems that are inherently complex to study. This article is protected by copyright. All rights reserved.
Acquiring movement data for small-bodied, deep-water chondrichthyans is challenged by extreme effects of capture and handling stress, and post-release predation, however, it is urgently required to examine important fisheries interactions and assess the ecological role of these species within deep-water food webs. Here we suggest a novel release-cage mechanism to deploy pop-up satellite archival tags, as well as present vertical habitat data for a data-deficient, small-bodied, deep-water bycatch species, the Cuban dogfish (Squalus cubensis). Data were gathered from seven of eight High Rate X-Tags deployed on mature Cuban dogfish in the Exuma Sound, The Bahamas. Recovery periods appeared variable between individuals and are likely driven by capture-and-handling stress and tag burden. Application of the cross-correlation function to time-series depth and temperature data indicated three of the seven individuals suffered mortality through predation, which occurred during daytime, and suggests Cuban dogfish may constitute a proportion of deep-water apex predator diet in the Exuma Sound. Two animals were successfully released via a novel release-cage mechanism and displayed either no, or rapid (< 15 mins) vertically stationary recovery periods and were not consumed by predators; data for these individuals were recorded for the entire deployment duration (14 days). Vertical habitat data suggests Cuban dogfish are diel-vertical migrators, similar to other deep-water taxa, and exhibit a relatively broad temperature and depth range, which may be driven by preference for specific bathymetric structures. These techniques provide an important first step into acquiring and presenting vertical habitat data for small-bodied, deep-water chondrichthyans, which can be directly applied to fisheries and ecosystem-based management approaches.
The response to capture is important in fisheries because it can reveal potential threats to species beyond fishing mortalities resulting from direct harvest. To date, the vast majority of studies assessing shark stress responses have used physiology or biotelemetry to look at sensitivity after capture, leaving a gap in our understanding of the behaviours of sharks during capture. We examined the behavioural responses of sharks to capture by attaching accelerometers to fishing gear and measuring the immediate and prolonged forces they exerted while on the line. We recorded acceleration vectors and derived the rate of intense fighting behaviours of 23 individual sharks comprising three species. Results suggest that blacktip sharks (Carcharhinus limbatus) exhibited intense bouts of fighting behaviour at the onset of hooking, while nurse (Ginglymostoma cirratum) and tiger sharks (Galeocerdo cuvier) displayed more subdued acceleration values during capture. We also obtained plasma lactate from a subset of ind...
Rebuilding of some U.S. West Coast rockfish (Sebastes spp.) stocks relies heavily on mandatory fishery discard, however the long-term condition of discarded fish experiencing capture-related barotrauma is unknown. We conducted two studies designed to evaluate delayed mortality, physical condition, and behavioral competency of yelloweye rockfish, Sebastes ruberrimus, experiencing barotrauma during capture followed by recompression (assisted return to depth of capture). First, we used sea-cage and laboratory holding to evaluate fish condition at 2, 15, and 30 days post-capture from 140 to 150 m depth. All external barotrauma signs resolved following 2 days of recompression, but fish that survived (10/12) had compromised buoyancy regulation, swim bladder injuries, and coelomic and visceral hemorrhages at both 15 and 30 days post-capture. For the second study, we used a video-equipped sea-cage to observe fish behavior for one hour following capture and return to the sea floor. Trials were conducted with 24 fish captured from 54 to 199 m water depth. All fish survived, but 50% of fish from the deepest depth ranges showed impairment in their ability to vertically orient (P < 0.01). Most (75%) deep-captured fish did not exhibit “vision-dependent” behavior (P < 0.001) and appeared unable to visually discern the difference between an opaque barrier and unobstructed or transparent components of the cage. These studies indicate physical injuries and behavioral impairment may compromise yelloweye rockfish in the hours and weeks following discard, even with recompression. Our results reiterate the importance of avoiding fishing contact with species under stock rebuilding plans, especially in deep water, and that spatially-managed rockfish conservation areas remain closed to fishing.
A total of nine leafscale gulper sharks Centrophorus squamosus (Bonnaterre, 1788), were tagged with pop-up, satellite, archival, transmitting tags (PSAT) in the Marine Protected Area (MPA) of El Cachucho (Le Danois Bank) located in waters to the north of Spain, (NE Atlantic). Tags provided data on time, pressure and temperature that were used to examine movement patterns and diving behavior. Data collected from Argo floats in the study area have been used to devise a simple geolocation algorithm to infer the probable routes followed by this species. Tag release points revealed that C. squamosus moved both to the west (Galician waters) and to the north (Porcupine Bank) from the tagging area, suggesting well defined preferred pathways. The inferred trajectories indicated that sharks alternate periods constrained to specific geographical regions with quick and prompt movements covering large distances. Two sharks made conspicuous diurnal vertical migrations being at shallower depths around midnight and at maximum depths at midday, while other sharks did not make vertical migrations. Vertical movements were done smoothly and independently of the fish swimming long-distances or resting in the area. Overall results confirm that this species is highly migratory, supporting speeds of 20 nautical miles.day-1 and well capable to swim and make vertical migrations well above the abyssal plain.
There are significant conservation benefits to studying the stress response of commercially important fish species. Particularly in the Arctic ecosystem, where reducing ice extent has resulted in heightened interest in developing commercial fisheries, there is a need to better understand how fish respond to capture stressors. To that end, blood lactate and glucose of Greenland halibut Reinhardtius hippoglossoides and Greenland shark Somniosus microcephalus were assessed after capture from fishing gear to evaluate factors that might influence physiological disturbance. Greenland halibut lactate values had a mean of 1.0 ± 0.7 mmol/L and showed a positive relationship with time since capture. Blood glucose concentrations for Greenland halibut had a mean of 1.8 ± 0.6 mmol/L and were positively related to both time since capture and fork length. Greenland shark lactate values varied depending on depth, with individuals captured at 300–600 m displaying significantly lower concentrations (1.6 ± 0.5 mmol/L) than those caught at depths between 600 and 700 m (6.4 ± 2.4 mmol/L) and 700–900 m (3.7 ± 1.2 mmol/L). Glucose values for the Greenland shark had a mean of 4.9 ± 1.5 mmol/L and were positively correlated with body length. Relative to temperate fish species, the metabolite concentrations are low but the inherent challenges with deep-water fish makes it difficult to obtain baseline (pre-stress) values to quantify the magnitude of stress response. This is the first study to document stress metabolites in these two Arctic species and suggests that there is a body size and depth-related physiological response to capture.
Background: The spatial ecology of deepwater demersal teleosts is poorly understood, and this group of fishes has rarely been studied using conventional or electronic means to discern movement and migration. Likewise, the development of management tools for such species has received less attention as compared to shallow water species, and there are few fishery closed area systems developed for the purpose of managing deepwater demersal fishes. The eteline snappers, which occur in depths of 100 to 400m, are an important fishery resource throughout the tropical Pacific, and are believed to be vulnerable to over-exploitation. Results: Deepwater eteline snappers were tagged with acoustic transmitters and detected on a network of listening stations that encompassed a fishery closed area in the Main Hawaiian Islands. Differences were detected in movement between species, with the bentho-pelagic Etelis coruscans moving more frequently and over slightly longer distances (1.4 movements/day detected, interquartile range (IQR) 0.0-2.4; maximum distance 4.7km, interquartile (IQR) 4.7-6.4km) than the demersal Etelis carbunculus (0.0 movements/day detected, interquartile range 0.0-0.3; maximum distance 4.7km, interquartile range 4.6-4.7km). The maximum single movement distance was 8.9km for E. coruscans and 4.7km for E. carbunculus. The median length dimension for bottomfish closed areas in the Main Hawaiian Islands is 9.2km (IQR) range 7.3-13.0km). Conclusions: Knowledge of the spatial ecology of animals is essential to understanding the effects of spatial management measures such as marine reserves. Differences between species indicate that effective reserve size will differ depending on the species. These results suggest that the reserves set up for bottomfish in the Main Hawaiian Islands are likely to have effects in reducing fishing mortality for E. carbunculus due to its low rate of cross border movement.
The return and survival of tagged fish to their depth of capture has proved difficult due to barotrauma and predation in previous telemetry studies. Tagging stress can slow and disorient the fish upon release, and reduce the ability to return to depth, relocate their home habitat site, and evade predators. To reduce these initial tag and release artifacts we designed and tested a remotely opening cage for use with reef fish in the northern Gulf of Mexico. Our objectives were to quickly return transmitter tagged fish to depth (20–30 m) in close proximity (<10 m) to their capture site, and to increase survival by providing predator protection during an initial recovery period. This cage release method proved successful for both red snapper (Lutjanus campechanus; n = 62 out of 71, 87%) and all gray triggerfish (Balistes capriscus; n = 24) that were tagged and released on artificial reefs. All tagged fish were released from November 2012 to September 2014, no initial tag induced mortalities were observed, and after tagging fish were successfully tracked for extended periods (for the entire 2 year study period).
In Uria lomvia individual dives were a flattened U shape in profile, and occurred in bouts lasting cl5 min. Dive patterns were nocturnal; most dives occurred between 2000-0400. Murres probably concentrate their foraging effort at times when prey is most available as it migrates closer to the surface in the evening as part of the deep scattering layer. Although dives averaged 18m in depth and 55s in duration, most time-at-depth was spent between 21-40m. Thus, murres made large number of shallow, short-duration dives. Maximum dive depth was 210m; maximum dive duration was 224s. Total useable oxygen store was calculated as 44.8 mL/kg, giving an estimated aerobic dive limit (ADL) of 47s. Murres exceeded the calculated ADL in 48% of their dives. Long-duration diving is probably a more efficient foraging strategy for murres given their relatively small size and limited oxygen storage capabilities. -from Authors
Deep-sea chondrichthyans, like many deep-water fishes, are very poorly understood at the most fundamental biological, ecological and taxonomic levels. Our study represents the first ecological investigation of deep-water elasmobranch assemblages in The Bahamas, and the first assessment of species-specific resilience to capture for all of the species captured. Standardised deep-water longline surveys (n=69) were conducted September to December 2010 and 2011 between 472. m and 1024. m deep, resulting in the capture of 144 sharks from 8 different species. These included the Cuban dogfish, Squalus cubensis, the bigeye sixgill shark, Hexanchus nakamurai, the bluntnose sixgill shark, Hexanchus griseus, the smooth dogfish, Mustelus canis insularis, the roughskin dogfish, Centroscymnus owstoni, Springer[U+05F3]s sawtail catshark, Galeus springeri and the false catshark, Pseudotriakis microdon. Preliminary genetic analysis indicated two or more species of gulper sharks, Centrophorus spp.; however, for the present study they were treated as a single species complex. Water depth and distance from the rocky structure of the Exuma Sound wall were inversely correlated with species richness, whereas seabed temperature was directly correlated with species richness. These variables also had a significant influence on the abundance and distribution of many species. Expanded depth ranges were established for S. cubensis and H. nakamurai, which, in the case of S. cubensis, is thought to be driven by thermal preferences. At-vessel mortality rates increased significantly with depth, and post-release mortality was thought to be high for some species, in part due to high post-release predation. This study highlights the importance of utilising strategic geographic locations that provide easy access to deep water, in combination with traditional expedition-based deep-ocean science, to accelerate the acquisition of fundamental ecological and biological insights into deep-sea elasmobranchs.
Interactions between upper trophic‐level predators and their prey remain poorly understood due to their inaccessibility during foraging at sea. This uncertainty has fuelled debate on the impact of predation by species such as the grey seal ( Halichoerus grypus ) on fish stocks.
The Vemco Mobile Transceiver (VMT) has provided us with new knowledge on interactions between pinnipeds and fish species. However, the necessity to recover the VMT for data retrieval has limited deployments to locations where confidence in instrument recovery is high, and has thus restricted both species and geographical sampling.
To overcome these limitations, a Bluetooth link was integrated into the VMT and GPS satellite‐linked transmitter. The two‐unit design allows data collected by the VMT to be transmitted via Bluetooth to the satellite transmitter, which relays the interaction data to the ARGOS satellite system for retrieval.
To evaluate in‐situ performance, units were deployed on two adult female grey seals on Sable Island, NS in October 2012 and recovered during the subsequent breeding season. Data archived by the VMT were compared with data uploaded via ARGOS.
The deployment periods were 76–84 days. The total number of valid detections archived was 179. All detections archived by the first unit ( n = 66) were transmitted via ARGOS, while all but two of the 113 archived detections from the second unit were transmitted. Detections recovered from both units were from other VMT‐tagged grey seals ( n = 173) and moored V13 transmitters on Middle Bank, Eastern Scotian Shelf ( n = 6).
These preliminary results are proof‐of‐concept that integrated Bluetooth VMTs can be used on a broader variety of marine predators to collect data on species interactions in otherwise inaccessible environments and without the need to recover instruments.
Deep-water sharks are considered highly vulnerable species due to their life characteristics and very low recovery capacity against overfishing. However, there is still limited information on the ecology or population connectivity of these species. The aim of this study was to investigate if the species Centrophorus squamosus could make long displacements and thus confirm the existence of connectivity between different deep-water areas. In addition, the study was the first attempt to use tagging techniques on deep-water sharks, since it has never been undertaken before. Five C. squamosus were tagged with satellite tags (PAT) in the El Cachucho Marine Protected Area (Le Danois Bank) located in waters of the North of Spain, Cantabrian Sea (NE Atlantic). Data from four of these tags were recovered. One of the sharks travelled approximately 287 nm towards the north east (French continental shelf) hypothetically following the continental slope at a mean depth of 901±109 m for 45 days. Two other sharks spent almost 4 months travelling, in which time they moved 143 and 168 nm, respectively, to the west (Galician coast). Finally, another leafscale gulper shark travelled to the NW (Porcupine Bank) during a period of 3 months at a mean depth of 940±132 m. Depth and temperature preferences for all the sharks are discussed. Minimum and maximum depths recorded were 496 and 1,848 m, respectively. The temperature range was between 6.2–11.4 °C, but the mean temperature was approximately 9.9±0.7 °C. The sharks made large vertical displacements throughout the water column with a mean daily depth range of 345±27 m. These preliminary results support the suggestion of a whole population in the NE Atlantic and confirm the capacity of this species to travel long distances.
This paper presents a prototype system that enables an autonomous underwater vehicle (AUV) to autonomously track and follow a shark that has been tagged with an acoustic transmitter. The AUV's onboard processor handles both real-time estimation of the shark's two-dimensional planar position, velocity, and orientation states, as well as a straightforward control scheme to drive the AUV toward the shark. The AUV is equipped with a stereo-hydrophone and receiver system that detects acoustic signals transmitted by the acoustic tag. The particular hydrophone system used here provides a measurement of relative bearing angle to the tag, but it does not provide the sign (+ or −) of the bearing angle. Estimation is accomplished using a particle filter that fuses bearing measurements over time to produce a state estimate of the tag location. The particle filter combined with a heuristic-based controller allows the system to overcome the ambiguity in the sign of the bearing angle. The state estimator and control scheme were validated by tracking both a stationary tag and a moving tag with known positions. Offline analysis of these data showed that state estimation can be improved by optimizing diffusion parameters in the prediction step of the filter, and considering signal strength of the acoustic signals in the resampling stage of the filter. These experiments revealed that state estimate errors were on the order of those obtained by current long-distance shark-tracking methods, i.e., manually driven boat-based tracking systems. Final experiments took place in SeaPlane Lagoon, Los Angeles, where a 1-m leopard shark (Triakis semifasciata) was caught, tagged, and released before being autonomously tracked and followed by the proposed AUV system for several hours. © 2013 Wiley Periodicals, Inc.
the last decade, several hundred seals have been equipped with
conductivity-temperature-depth sensors in the Southern Ocean for both
biological and physical oceanographic studies. A calibrated collection
of seal-derived hydrographic data is now available, consisting of more
than 165,000 profiles. The value of these hydrographic data within the
existing Southern Ocean observing system is demonstrated herein by
conducting two state estimation experiments, differing only in the use
or not of seal data to constrain the system. Including seal-derived data
substantially modifies the estimated surface mixed-layer properties and
circulation patterns within and south of the Antarctic Circumpolar
Current. Agreement with independent satellite observations of sea ice
concentration is improved, especially along the East Antarctic shelf.
Instrumented animals efficiently reduce a critical observational gap,
and their contribution to monitoring polar climate variability will
continue to grow as data accuracy and spatial coverage increase.
[1] Over the last decade, several hundred seals have been equipped with conductivity-temperature-depth sensors in the Southern Ocean for both biological and physical oceanographic studies. A calibrated collection of seal-derived hydrographic data is now available, consisting of more than 165,000 profiles. The value of these hydrographic data within the existing Southern Ocean observing system is demonstrated herein by conducting two state estimation experiments, differing only in the use or not of seal data to constrain the system. Including seal-derived data substantially modifies the estimated surface mixed-layer properties and circulation patterns within and south of the Antarctic Circumpolar Current. Agreement with independent satellite observations of sea ice concentration is improved, especially along the East Antarctic shelf. Instrumented animals efficiently reduce a critical observational gap, and their contribution to monitoring polar climate variability will continue to grow as data accuracy and spatial coverage increase.