Article

Tracking and Following a Tagged Leopard Shark with an Autonomous Underwater Vehicle

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Abstract

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.

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... Only few papers related to moving sensors (on autonomous vehicles), and for underwater applications can be found. For example, in [7] the authors use four Gliders for maritime vehicle tracking, and in [8] a procedure for animal tracking with an Autonomous Underwater Vehicle (AUV) is proposed. ...
... In particular, this latter work has the same aim which is presented in this paper. However, while in [8] a method for animal tagged tracking and following is developed, by an array of two hydrophones attached on an AUV (and therefore they use the bearing measurements), we study the case where both the target and the vehicle are equipped with a very basic acoustic transponder providing only range information between target and vehicle. Moreover, we propose a complete study including performance characterization of the system and derivation of optimum values (such as speed ratio and range frequency). ...
... On the other hand, the scientific community has paid attention to the Sequential Monte Carlo Methods (SMCM) such as PF for its capability of solving nonlinear estimation problems with multimodal pdf. Such as in [8]. ...
... The problem of target localization and pursuit has received widespread attention due to its importance in a vast number of applications in the areas of marine science, surveillance and reconnaissance, search-and-rescue, and military operations, see [1]- [4]. In the literature, localization usually refers to the problem of finding the location of an unknown stationary target, while tracking refers to the task of estimating the trajectory of a moving target. ...
... See also [8] for optimal sensor placement solutions in the case of multiple static targets and sensors. In recent years, there has been growing interest in exploiting the use of single or multiple mobile sensors (called trackers) for target localization, focusing on applications with unmanned aerial vehicles (UAVs) and autonomous marine vehicles (AMVs), see for example [1], [9]- [13] and the references therein. In this setup, the trackers carry range measuring devices to acquire successive ranges to the targets of interest and use the range information to estimate the state of each target. ...
... The tracker's model (1) can now be rewritten as ...
Article
We address the general problem of multiple target localization and pursuit using measurements of the ranges from the targets to a set of autonomous pursuing vehicles, referred to as trackers. We develop a general framework for targets with models exhibiting uncertainty in the initial state, process, and measurement noise. The main objective is to compute optimal motions for the trackers that maximize the range-based information available for target localization and at the same time yield good target pursuit performance. The solution proposed is rooted in an estimation-theoretical setting that involves the computation of an appropriately defined Bayesian Fisher Information Matrix (FIM). The inverse of the latter yields a posterior Cramér-Rao Lower Bound (CRLB) on the covariance of the targets’ state estimation errors that can be possibly achieved with any estimator. Using the FIM, sufficient conditions on the trackers’ motions are derived for the ideal relative geometry between the trackers and the targets for which the range information acquired is maximal. This allows for an intuitive understanding of the types of ideal tracker trajectories. To deal with realistic constraints on the trackers’ motions and the requirement that the trackers pursue the targets, we then propose a model predictive control (MPC) framework for optimal tracker motion generation with a view to maximizing the predicted range information for target localization while taking explicitly into account the trackers’ dynamics, strict constraints on the trackers’ states and inputs, and prior knowledge about the targets’ states. The efficacy of the MPC is assessed in simulation through the help of representative examples motivated by operational scenarios involving single and multiple targets and trackers.
... For example, buoyancy-driven Slocum gliders with integrated VEMCO cabled receivers (VR2c) or externally mounted mobile transceivers (VMTs) have been used to study sturgeon and shark habitats [3][4][5]. Lotek stereo-hydrophone acoustic receiver systems have been integrated into propelled OceanServer IVER2 AUVs to track and follow leopard sharks [6,7]. VEMCO receivers have been externally mounted and Lotek hydrophones integrated into a propeller-driven REMUS-100 AUV [8,9]. ...
... The detection range of an acoustic receiver is dependent on the acoustic landscape, both the background noise and the propagation environment, as well as the receiver array configuration [2,[11][12][13][14]. Therefore, to ensure an AUV is an efficient telemetry asset, it is necessary to conduct range tests, have onboard processing for geolocation or use multiple vehicles for coordinated path planning based on received detections [6][7][8]. Propelled vehicles are aptly suited for the latter tasks but due to the high power cost of propelled motion, they are restricted by battery life to deployments often lasting < 1 day. In comparison, buoyancy-or wave-driven vehicles can conduct continuous surveys for months and can adapt their location to stay within biologically interesting regions, which may migrate in space, in contrast to measurements from fixed arrays. ...
... Our results suggested the mounting orientation of a receiver is critical to the success of hydrophone system and should be given thorough consideration and testing when using new platforms. Past studies using autonomous vehicles have had different mounting configurations, including horizontal VMTs or hydrophones facing forward or backward [9,10,16], an upward and/ or downward facing VR2c with some on an angle [6,7,10,16] or towing a VR2c that likely results in a variable orientation [15]. While most of these studies did not conduct a thorough range test, it is possible that receiver orientation in combination with different platform types (buoyancy driven, wave harnessing or propelled) could lead to different detection rates. ...
Article
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Background Detecting tagged animals in coastal environments is often limited to stationary arrays of acoustic receivers that can decode transmissions from tags on animals. However, mobile autonomous platforms are becoming important tools that support the science of understanding biophysical relationships because they can concurrently detect tagged individuals and measure properties of their ocean habitat. To assess the effectiveness of these emerging platforms, proper validation and range detection studies are necessary. Here, we report on the deployment of a wave powered unmanned surface vessel, the Liquid Robotics Wave Glider SV3, equipped with a forward- and backward-facing acoustic receiver (VR2W) and transceiver (VR2Tx) at 4 m depth. Surveys were conducted around two stationary moorings equipped with receivers, transceivers or tags emitting signals with different power outputs. Results During our study, the sea state was mild with low wind speeds (< 10 kts) and small wave heights (< 0.8 m). We determined the influence of environmental and vehicle factors on the detection range of transmitters with various power outputs. Overall, the highest detection efficiencies (~ 50–95%) were at distances < 0.1 km, lower detection efficiencies (0.1–50%) were > 0.5 km and the maximum range was 0.5–1.2 km. The forward-facing receiver had almost half the detection efficiency of the backward-facing transceiver, suggesting a backward configuration is optimal to reduce the influence of the moving platform. The higher power output transmitters had a 20% detection efficiency to ranges of ~ 0.5 km (153 dB) and ~ 0.8 km (160 dB). Distance between the receiver and transmitter was the main factor affecting detection probability, with background noise, receiver heading, angle between transmitter and receiver and wave height also being important. Wind speed, water temperature, mooring line tilt angle and vehicle dynamics were found not to be as important over the limited range of conditions over which our study was conducted. Conclusions Wave Gliders equipped with receivers can provide useful data and can be an effective biotelemetry asset that could supplement stationary arrays of acoustic receivers or act as an exploratory technology to search for biologically important areas.
... (e.g., autonomous surface or underwater vehicles) has received widespread attention in recent years due to its importance in a vast number of applications in the areas of marine science, surveillance and reconnaissance, search-and-rescue, and military operations, [1]- [5]. In this setup, the trackers are equipped with acoustic devices that measure ranges to the target and use this information to estimate the state of the latter (localization task) while keeping a desired relative geometric formation in a predefined vicinity of the target to acquire maximal range information about it for estimation purposes (pursuit task) [5], [6]. ...
... It was explained in the previous section that if trackers can be controlled such that they converge to their corresponding S-T curves, then the pursuit task stated in Problem 1 will be fulfilled. In addition, with this design, if the paths r [i] (·), i ∈ V, are parameterized appropriately such that γ [1] 0 − γ [2] 0 = π/2 for N = 2 and ...
... where γ [γ [1] , . . . , γ [N ] ] ∈ R N and ...
Article
We study the problem of using single or multiple cooperative autonomous vehicles, called trackers, to localize and pursue an unknown underwater moving target using measurement of the ranges between the tracker(s) and the target. At the motion planning level, each tracker is assigned a spatial-temporal (S-T) curve to track that is generated by the composition of two types of motion: along the target's trajectory and on a path encircling the target. At the control level, we derive control laws for robust trajectory tracking and show that under mild assumptions on the convergence of the target's state estimate provided by a suitably designed filter, the tracker converges to and remains in a desired vicinity of the target. For the case of multiple trackers, we propose an efficient distributed estimation and control (DEC) strategy for the trackers that consider explicitly the constraints on the intertracker communication network. To this end, a distributed extended Kalman filter (DEKF) and a distributed control law for cooperative S-T curve tracking are developed to cooperatively pursue and localize the target. Using this setup, all trackers converge to a specified vicinity of the target while keeping an optimal tracker-target relative geometry that maximizes the range information acquired to estimate the target's state. The stability of the complete closed-loop DEC system is analyzed rigorously and the efficacy of the proposed strategy is illustrated with extensive computer simulations for the 2-D and 3-D cases. /............../ Preprint version can be downloaded at: https://nt-hung.github.io/files/pdf/research/IEEE_TCST_preprint.pdf
... Autonomous underwater vehicles (AUVs) are increasingly being used to supplement the use of surface vessels for measuring the physical, chemical, and biological characteristics of the marine environment, and when equipped with acoustic receivers can be used to determine the distribution and movements of fish tagged with acoustic transmitters [13,14]. This approach has definite advantages over tracking fish from surface vessels, particularly for demersal or deep-water pelagic species [15]. ...
... The use of AUVs to locate acoustically tagged fish has been enhanced by advances in payload control (PC) hardware and software, which allow the vehicle to alter its mission in response to information from an on-board sensor (i.e., reactive sampling), in this case telemetry data from an integrated acoustic receiver. This approach has been used to track the Lagrangian movements of a single acoustically tagged fish [14,21]. However, repeatedly locating multiple fish over a vast area remains a major challenge. ...
Article
Full-text available
An autonomous underwater vehicle (AUV) under payload control (PC) was used to map the movements of juvenile Chinook salmon (Oncorhynchus tshawytscha) tagged with acoustic transmitters. After detecting a tag, the AUV deviated from its pre-programmed route and performed a maneuver designed to enhance the location estimate of the fish and to move closer to collect proximal environmental data. Nineteen fish were released into marine waters of southeastern Alaska. Seven missions with concurrent AUV and vessel-based surveys were conducted with two to nine fish present in the area per mission. The AUV was able to repeatedly detect and estimate the location of the fish, even when multiple individuals were present. Although less effective at detecting the fish, location estimates from the vessel-based surveys helped verify the veracity of the AUV data. All of the fish left the area within 48 h of release. Most fish exhibited localized movements (milling behavior) before leaving the area. Dispersal rates calculated for the fish suggest that error associated with the location estimates was minimal. The average movement rate was 0.62 body length per second and was comparable to marine movement rates reported for other Chinook salmon stocks. These results suggest that AUV-based payload control can provide an effective method for mapping the movements of marine fish.
... To enable active tracking without the need for human operators, the authors have demonstrated that Autonomous Underwater Vehicles (AUVs), equipped with a stereo-hydrophone system that provides angle-to-tag measurements, are able to autonomously track and follow tagged leopard sharks [3]. Key developments by Forney et al. included a particle filter shark state estimator that could accommodate the low-resolution, lowsampling frequency and the sign ambiguity associated with angle measurements of the stereohydrophone system [4]. ...
... Another method to obtain distance-to-tag measurements is by determining the relationship between received signal strength and distance a priori, before using this relationship in-situ. While there exists a negative correlation between distance and signal strength, the relationship is non-linear and highly dependent on environmental variables [3]. Hence, extracting distance measurements using this relationship often leads to high localization errors. ...
Conference Paper
Full-text available
Tracking fish has primarily been ac-complished using acoustic telemetry. Typically, a fish is tagged, released, and manually tracked using hydrophones that detect acoustic tag transmissions. More recently, such hydrophone receiver systems have been mounted on Autonomous Underwater Vehicles (AUVs) to increase system mobility. This paper presents a new method for determining the distance from a tag to an AUV equipped with such a hydrophone system. By first estimating the trans-mission time of a tag signal, the time-of-flight can be used to calculate the distance to a tag. Further-more, the calculated distance can be incorporated into an online state estimator to more accurately localize a tagged target. Results indicate significant improvement in an AUV's ability to localize a target when the distance to tag calculations are used in combination with angle-to-tag measurements.
... To enable active tracking without the need for human operators, the authors have demonstrated in previous works that a multi-AUV system using only low resolution angle measurements is able to autonomously track and follow tagged leopard sharks [3]. A key component of this system is a state-estimator which determines the 2D position of the tagged shark [4]. ...
... Due to lack of odometry from the tag, a stochastic motion model is used in the prediction step of the state-estimator to propagate the particles. The motion model used is described in Alg. 2 and builds upon [3]. It is best described as a hybrid Brownian and Levy Flight motion model. ...
Conference Paper
Full-text available
This paper presents a multi-AUV state-estimator that can determine the 3D position of a tagged fish. In addition to angle measurements, the state-estimator also incorporates distance and depth measurements. These additional sensor measurements allow for greater accuracy in the position es-timates. A newly developed motion model that better accounts for multiple hypotheses of the motion of a tagged fish is used to increase the robustness of the state-estimator. A series of multi-AUV shark tracks were conducted at Santa Catalina Island, California over the span of four days to demonstrate the ability of the state-estimator to determine the 3D position of a tagged leopard shark. Additional experiments in which the AUVs tracked a tagged boat of known location were conducted to quantify the performance of the presented state-estimator. Experimental results demonstrate a three-fold decrease in mean state-estimation error compared to previous works.
... The first to use an underwater drone to study sharks was Clark et al. [9], who actively tracked an acoustically tagged leopard shark (Triakis semifasciata) in a coastal lagoon. In that study, the drone was constrained to the surface, was not equipped with cameras (for behavioural observations), lacked the capacity to monitor animal depth, and resulted in a coarse estimate of the shark's horizontal movements. ...
... Packard et al. [13] were the first to mount cameras on an underwater drone for the sole purpose of observing behaviour while actively tracking sharks and collecting environmental data at depth. These authors used a REMUS (Remote Environmental Monitoring UnitS; Woods Hole Oceanographic Institution, Woods Hole, MA, USA) drone, which was developed as a platform for a wide variety of oceanographic instrumentation and outfitted with a Global Positioning System (GPS), wireless communication, iridium capabilities, an inertial navigation system, ring laser gyroscopes to orient the vehicle spatially, and accelerometers to sense changes in speed and velocity [9]. The drone also carried a variety of sensors including an acoustic Doppler current profiler, a conductivity-temperature probe, magnetic heading sensor, and pressure sensor. ...
Article
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Over the past decade, drones have become a popular tool for wildlife management and research. Drones have shown significant value for animals that were often difficult or dangerous to study using traditional survey methods. In the past five years drone technology has become commonplace for shark research with their use above, and more recently, below the water helping to minimise knowledge gaps about these cryptic species. Drones have enhanced our understanding of shark behaviour and are critically important tools, not only due to the importance and conservation of the animals in the ecosystem, but to also help minimise dangerous encounters with humans. To provide some guidance for their future use in relation to sharks, this review provides an overview of how drones are currently used with critical context for shark monitoring. We show how drones have been used to fill knowledge gaps around fundamental shark behaviours or movements, social interactions, and predation across multiple species and scenarios. We further detail the advancement in technology across sensors, automation, and artificial intelligence that are improving our abilities in data collection and analysis and opening opportunities for shark-related beach safety. An investigation of the shark-based research potential for underwater drones (ROV/AUV) is also provided. Finally, this review provides baseline observations that have been pioneered for shark research and recommendations for how drones might be used to enhance our knowledge in the future.
... The imaging capabilities on UAS, ROV (remotely operated vehicle), and AUV (autonomous underwater vehicle) platforms allow researchers to discretely record photos and videos from animals exhibiting natural behaviors, and this is becoming more prevalent in studies of marine megafauna [20][21][22][23][24][25][26][27][28][29][30][31]. The utilization of aerial drones for elasmobranch research is an emergent technique that has provided a new tool for scientists to explore the life history and behaviors of various species. ...
... Similarly, if the sharks were located deeper in the water column, distortion from the water's surface would prevent clear visualization of the animals and make this project less feasible. More challenging conditions may be an opportunity for other technologies such as ROVs and AUVs to film animals swimming either above or below the platform [29][30][31]. The specific requirements of clear water, and a relatively distortion-free surface, limit the utility of this technique, however this fine scale data collection may be possible in other study systems where aerial surveys and drone technology are being utilized and can allow for studying animals with a lens toward biomechanics within movement ecology paradigms [17,18,32,38,39,67]. ...
Article
Full-text available
Recent work showed that two species of hammerhead sharks operated as a double oscillating system, where frequency and amplitude differed in the anterior and posterior parts of the body. We hypothesized that a double oscillating system would be present in a large, volitionally swimming, conventionally shaped carcharhinid shark. Swimming kinematics analyses provide quantification to mechanistically examine swimming within and among species. Here, we quantify blacktip shark (Carcharhinus limbatus) volitional swimming kinematics under natural conditions to assess variation between anterior and posterior body regions and demonstrate the presence of a double oscillating system. We captured footage of 80 individual blacktips swimming in the wild using a DJI Phantom 4 Pro aerial drone. The widespread accessibility of aerial drone technology has allowed for greater observation of wild marine megafauna. We used Loggerpro motion tracking software to track five anatomical landmarks frame by frame to calculate tailbeat frequency, tailbeat amplitude, speed, and anterior/posterior variables: amplitude and frequency of the head and tail, and the body curvature measured as anterior and posterior flexion. We found significant increases in tailbeat frequency and amplitude with increasing swimming speed. Tailbeat frequency decreased and tailbeat amplitude increased as posterior flexion amplitude increased. We found significant differences between anterior and posterior amplitudes and frequencies, suggesting a double oscillating modality of wave propagation. These data support previous work that hypothesized the importance of a double oscillating system for increased sensory perception. These methods demonstrate the utility of quantifying swimming kinematics of wild animals through direct observation, with the potential to apply a biomechanical perspective to movement ecology paradigms.
... They have enabled explorations of environments and species at extreme aquatic conditions and depths (see Yoerger et al. 2000). For instance, they have enabled explorations under arctic ice sheets and have enabled safer aquatic predator monitoring (see, e.g., Wadhams et al. 2006 andClark et al. 2013). In these, and exceedingly many other, ways, drones and rovers alone have shown that general robotics technologies can substantially augment environmental research capabilities in ethically preferable ways. ...
... Such robots have also proven useful for monitoring existential threats and risks of losses and damages to different organisms' well-being capacities, by being used to monitor droughts, floods, extreme storms, and volcanoes for example (Choi-Fitzpatrick 2014, p. 24). For instance, they have been used to monitor and prevent poaching, and have been used to monitor the conditions of many different kinds of biological populations and communities (see, e.g., Ditmer et al. 2015;Clark et al. 2013;Le Maho et al. 2014;Whitcomb 2000;Vas et al. 2015). ...
Article
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New robotics technologies are being used for environmental research, and engineers and ecologists are exploring ways of integrating an array of different sorts of robots into ecosystems as a means of responding to the unprecedented environmental changes that mark the onset of the Anthropocene. These efforts introduce new roles that robots may play in our environments, potentially crucial new forms of human dependence on such robots, and new ways that robots can enhance life quality and environmental health. These efforts at once introduce a variety of new and unprecedented ethical concerns. This work uses a previously developed functional taxonomy of kinds of environmental robots to develop a list of key ethical questions to push forward the sub-field and study of Environmental Robot Ethics. By identifying unique concerns raised by the different sorts of existing environmental robotics technologies, this paper aims to provide resources for further critical analysis of the ethical issues and tradeoffs environmental robots present.
... Autonomous underwater vehicles (AUVs) are multipurpose mobile sensor platforms. They have performed oil spill surveys [5], shark tracking [3], and acoustic channel mapping [13] during the past decades. In these tasks, the localization of AUVs, or the positional estimation of AUVs, can be an essential issue for oceanographers and researchers in collecting data that requires high positional accuracy. ...
... The receiver passively listens to transmitted signals generated from the stationary transmitters. While previous work deals with such acoustic passive measurements with multiple receivers on an AUV, such as tracking a shark with a fish tag [3], our work solves the localization problem of an AUV equipped with one receiver that can detect multiple stationary transmitters installed at known locations. ...
Conference Paper
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The localization of autonomous underwater vehicles (AUVs) during subsurface travel is a challenging issue in that ocean flows are unknown and complex. This paper studies the localization problem of AUVs under ocean flows with spatial and temporal variability. To predict trajectories of AUVs, we develop an odometry model that employs the framework of controlled Lagrangian particle tracking. Odometry error, which is distinct from the classic odometry error of ground mobile robots, is affected by controllers of AUVs. We design a waypoint controller and then analytically derive the deterministic and stochastic error growth of odometry. This derivation ultimately allows us to develop discrete state and measurement equations for a particle filter algorithm that combines infrequent acoustic measurements and the odometry model. On-off acoustic measurements are provided by one receiver equipped in each AUV. Generating a graph from knowledge about non-disjoint regions composed of transmitters and detection ranges, we develop the particle filter algorithm with a special type of likelihood. This likelihood determines the weights of particles on the graph where real and predicted measurements are compared. The algorithms are verified by simulation results.
... The increasing miniaturization of tagging technologies will allow for tagging of increasingly small individuals and subsequently opening the doors to investigate more and more genera. One solution to reduce the size of tagging packages is to affix acoustic transmitters to the organism, which is then tracked by an autonomous underwater vehicle (AUV) equipped with environmental sensors (Clark et al., 2013;Skomal et al., 2015). Deploying an AUV with high-definition video capabilities will enable investigators to evaluate organismal behaviour. ...
... Deploying an AUV with high-definition video capabilities will enable investigators to evaluate organismal behaviour. These deployments have already been successful with sharks (Clark et al., 2013;Skomal et al., 2015), are currently underway for turtles and could also be achieved with jellyfish. As we continue to move to fully autonomous systems that can track individuals and aggregate jellyfish using less-invasive methods (e.g. ...
Article
Jellyfish have become a topic of interest of many marine scientists and managers alike due to their conspicuous socio-economic and environmental impacts. However, our knowledge about their “everyday life” remains limited. While electronic tags (transmitters and loggers) have been extensively used to study marine vertebrates for the past 50 years, tagging is still in its infancy for marine invertebrates and jellyfish in particular. Progress has been hampered by the difficulty and limited knowledge of attaching tags to soft-bodied animals. We argue that there is huge potential to use tagging to gather basic information on the ecology and behaviour of these species. Here, we give an overview of what has been learned so far by deploying tags on jellyfish, and why tagging is an appropriate method to study their behaviour and ecology. We then describe different tagging techniques, their advantages, disadvantages and challenges, and the steps to ensure future successful jellyfish tagging studies.
... One solution to this challenge is near-real-time triangulation of the acoustic signal using a combination synthetic aperture and known test tag locations [7]. Another solution is using a combination of stereo receivers and near-realtime particle filtering [8], and multiple AUVs to geolocate the acoustic tag on meter scales [9]. These approaches can be highly effective for geolocating acoustic signals, but require high-performance, propeller-driven AUVs that are able to precisely control their positions in the water. ...
Article
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Background Acoustic biotelemetry sensors have been fully integrated into a broad range of mobile autonomous platforms; however, estimates of detection efficiency in different environmental conditions are rare. Here, we examined the role of environmental and vehicle factors influencing detection range for two common acoustic receivers, the VEMCO mobile transceiver (VMT) and a VEMCO cabled receiver (VR2c) aboard a Teledyne Slocum glider. We used two gliders, one as a mobile transmitting glider and one as a mobile receiving glider during the fall in the mid-Atlantic coastal region. Results We found distance between gliders, water depth, and wind speed were the most important factors influencing the detection efficiency of the VMT and the VR2c receivers. Vehicle attitude and orientation had minimal impacts on detection efficiency for both the VMT and VR2c receivers, suggesting that the flight characteristics of the Slocum glider do not inhibit the detection efficiency of these systems. The distance for 20% detection efficiency was approximately 0.4 and 0.6 km for the VMT and VR2c, respectively. The VR2c receivers had significantly lower detection efficiencies than the VMT receiver at distances <0.1 km, but higher detection efficiencies than the VMT at distances >0.1 km. Conclusions Slocum gliders are effective biotelemetry assets that serve as sentinels along important animal migration corridors. These gliders can help elucidate the relationships between telemetered organisms and in situ habitat. Therefore, estimating the detection ranges of these common telemetry instruments provides an important metric for understanding the spatial scales appropriate for habitat selection inferences.
... In recent years, advances in autonomous underwater vehicles (AUVs) have benefit a wide-range of scientific applications, such as ocean monitoring (Rogowski et al., 2013;Williams et al., 2012;Zhang et al., 2012), underwater cavity exploration (Jenkins et al., 2012) and biological researches (Clark et al., 2013;Smale et al., 2012). The AUV is a promising technique because it is self-organised and works without remote control. ...
Article
Autonomous underwater vehicles (AUVs) form mobile underwater networks to conduct underwater surveying missions cooperatively. Due to the severe turbulence caused by water currents, individual AUV has to adjust its heading constantly to ensure reaching destination. The coordinated AUV network increases the size of the surveying area, but leads to bigger challenges on maintaining AUV network locations. In this paper, we consider the localisation problem for AUVs in a mobile multi-hop underwater network. In our approach, to avoid the accumulating errors caused by the inertial measurement units, we periodically re-localise the AUV network through surfacing a set of AUVs as beacons. A beacon AUV surfaces to obtain its accurate location information from external sources, such as satellites, and then submerges to adjust the locations for remaining AUVs through acoustic communication. Simulation result shows that our approach greatly improves the localisation accuracy and energy efficiency of the AUV network.
... In recent years, advances in autonomous underwater vehicles (AUVs) have benefit a wide-range of scientific applications, such as ocean monitoring (Rogowski et al., 2013;Williams et al., 2012;Zhang et al., 2012), underwater cavity exploration (Jenkins et al., 2012) and biological researches (Clark et al., 2013;Smale et al., 2012). The AUV is a promising technique because it is self-organised and works without remote control. ...
... Unlike the previous work [22], [23], [24] relating to autonomous tracking of tagged individuals with AUVs, this work presents stochastic control systems that utilize either historical or real-time detections, capable of handling multiple AUVs and tagged individuals. These control systems allocate robots according to changing target densities. ...
... With their ability to dive directly into the fish habitat and survey deeper waters, underwater vehicles of various designs so far appear to be the most commonly used vehicle type for carrying acoustic receivers (Grothues et al., 2008;Oliver M. et al., 2013;Lin et al., 2017;Ennasr et al., 2020;Masmitja et al., 2020). Autonomous underwater vehicles (AUVs) with electric thrusters are relatively fast and have field-proven capabilities of detecting and localising acoustically tagged fish (Clark et al., 2013;Eiler et al., 2013;Eiler et al., 2019), but onboard energy resources strictly constrain mission times for these platforms, and they often require proximity to ship or shore for communication and navigational assistance. However, the integration of acoustic receivers into underwater gliders that feature an energyefficient buoyancy-driven propulsion mechanism mitigates this energy limitation to a large extent and enables long-term unassisted fish tracking missions even in remote oceanic regions (Oliver M. et al., 2013;Haulsee et al., 2015;Oliver et al., 2017). ...
Article
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Over the last few decades, acoustic fish telemetry has developed into a viable approach for remote monitoring of fish behaviour in the marine environment. Simultaneously, unmanned surface and underwater vehicles have found extensive use as scalable, persistent and cost-effective platforms for ocean observation. Equipping such robotic vehicles with fish telemetry receivers constitutes an emerging approach with the potential to significantly push the current operational limits of fish movement studies at sea. Here, we present an energy-autonomous robotic fish telemetry platform realised through the integration of a real-time acoustic receiver into an ocean-going wave-and solar-powered unmanned surface vehicle. The vehicle frame and energy harvesting solutions are based on the commercially available AutoNaut USV, while the vehicle's control and communication systems were developed using open-source software and standard hardware components. The open architecture permitted deep integration of the acoustic receiver as a system-level payload making fish detections and other sensor data available in real-time to the vehicle's onboard control system. The vehicle is thus prepared with local situational awareness to support autonomous control during vehicle-fish encounters, as well as conventional interfaces for remote piloting and data management through long-range wireless communication links and the Internet. The vehicle concept was investigated theoretically and experimentally in an acoustic range test and a full-scale sea trial. When driven passively by waves, tag detection performance was comparable to that of traditional moored receivers, while activation of the auxiliary electric thruster caused a reduction in detection radius of more than 50%, confirming wave-power as the ideal mode of propulsion. Finally, by deploying the AutoNaut over a period of several days at the outskirts of a Norwegian fjord during the seaward migration of Atlantic salmon post-smolts, we demonstrated that the vehicle was able to detect an acoustically tagged post-smolt into the open ocean beyond the reach of the fjord's stationary receiver grid, Frontiers in Marine Science | www.frontiersin.org while using only wave-and solar energy harvesting to power its operation. The ability to observe small individual fish in the ocean environment using an energy-autonomous robotic vehicle creates novel and unprecedented opportunities for scientific inquiry in fish behaviour and movement ecology studies at sea.
... M arine robotics has a significant impact on many related fields of research including marine ecology (Clark et al., 2013), oceanography (Fernandes et al., 2000;Eriksen et al., 2001;Grasmueck et al., 2006), and oceanic meteorology (Chao et al., 2008). Many design aspects of existing underwater robots were inspired by marine organisms that have been dominating the ocean for centuries. ...
Article
In this paper, a bioinspired, compact, cost-effective autonomous underwater vehicle system is presented. Designed to operate in a heterogeneous, multivehicle collaboration hierarchy, the presented vehicle design features 3D printing technology to enable fast fabrication with a complex internal structure. Similar to a previous vehicle prototype, this system generates propulsive forces by expelling unsteady, pulsed jets, inspired by the locomotion of cephalopods and jellyfish. The novel thrusters enable the vehicle to be fully actuated in horizontal plane motions, without sacrificing the low-forward-drag, slender vehicle profile. By successively ingesting water and expelling finite water jets, periodic actuation forces are generated at all possible vehicle velocities, eliminating the need for control surfaces used in many conventional underwater vehicle designs. A semiactive buoyancy control system, inspired by the nautilus, adjusts the vehicle depth by passively allowing water flowing into and actively expelling water out of an internal bladder. A compact embedded system is developed to achieve the control and sensing capabilities necessary for multiagent interactions with the minimum required processing power and at a low energy cost. The new vehicle design also showcases an underwater optical communication system for short-range, high-speed data transmission, supplementing the conventional acoustic communication system. Experimental results show that, with the thruster motors powered at a 60% duty-cycle, the new vehicle is able to achieve a 1/4 zero-radius turn in 3.5 s and one-body-width sway translation in 2.5 s.
... The authors have demonstrated in Clark et al. (2013) that a single AUV system using low-resolution angle measurements, distance measurements, and depth measurements is able to autonomously track and follow a tagged leopard shark. Key components of the system include a circle tracking controller and state estimator presented in Tang, Shinzaki, Lowe, & Clark (2012) and Lin et al. (2014). ...
Article
This paper presents a multi-autonomous underwater vehicle system capable of cooperatively and autonomously tracking and following marine targets (i.e., fish) tagged with an acoustic transmitter. The AUVs have been equipped with stereo-hydrophones that receive signals broadcasted by the acoustic transmitter tags to enable real-time calculation of bearing-to-tag and distance-to-tag measurements. These measurements are shared between AUVs via acoustic modem and fused within each AUV's particle filter for estimating the target's position. The AUVs use a leader/follower multi-AUV control system to enable the AUVs to drive toward the estimated target state by following collision-free paths. Once within the local area of the target, the AUVs circumnavigate the target state until it moves to another area. The system builds on previous work by incorporating a new SmartTag package that can be attached to an individual's dorsal fin. The SmartTag houses a full inertial measurement unit (INU), video logger, acoustic transmitter, and timed release mechanism. After real-time AUV tracking experiments, the SmartTag is recovered. Logged IMU data are fused with logged AUV-obtained acoustic tag measurements within a particle filter to improve state estimation accuracy. This improvement is validated through a series of multi-AUV shark and boat tracking experiments conducted at Santa Catalina Island, California. When compared with previous work that did not use the SmartTag package, results demonstrated a decrease in mean position estimation error of 25–75%, tag orientation estimation errors dropped from 80° to 30° , the sensitivity of mean position error with respect to distance to the tag was less by a factor of 50, and the sensitivity of mean position error with respect to acoustic signal reception frequency to the tag was 25 times less. These statistics demonstrate a large improvement in the system's robustness when the SmartTag package is used.
... instruments attached temporarily to marine mammals) (Boehme et al., 2010;Block et al., 2011), and acoustic listening networks, in which animals with implanted sensors are detected at listening nodes (O'Dor et al., 2009). The ability of autonomous underwater vehicles (AUVs) to track and detect telemetered animals is also becoming a significant tool for understanding seascapes (Grothues et al., 2008;Clark et al., 2013). AUVs provide greater environmental coverage than node-based detection, extend the depth capacity and spatial resolution of acoustic identification (Moline et al., 2016), and facilitate evaluation of dynamic habitat preference of foraging pelagic species (Oliver et al., 2013;Haulsee et al., 2015;Breece et al., 2016). ...
Article
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For terrestrial and marine benthic ecologists, landscape ecology provides a framework to address issues of complexity, patchiness, and scale—providing theory and context for ecosystem based management in a changing climate. Marine pelagic ecosystems are likewise changing in response to warming, changing chemistry, and resource exploitation. However, unlike spatial landscapes that migrate slowly with time, pelagic seascapes are embedded in a turbulent, advective ocean. Adaptations from landscape ecology to marine pelagic ecosystem management must consider the nature and scale of biophysical interactions associated with organisms ranging from microbes to whales, a hierarchical organization shaped by physical processes, and our limited capacity to observe and monitor these phenomena across global oceans. High frequency, multiscale, and synoptic characterization of the 4-D variability of seascapes are now available through improved classification methods, a maturing array of satellite remote sensing products, advances in autonomous sampling of multiple levels of biological complexity, and emergence of observational networks. Merging of oceanographic and ecological paradigms will be necessary to observe, manage, and conserve species embedded in a dynamic seascape mosaic, where the boundaries, extent, and location of features change with time.
... The idea of tracking an animal with an AUV is not unique. Clark et al. (2013) used an AUV to follow a T. semifasciata off the coast of California for up to 1⋅67 h. In that approach, they used a particle filter to produce a state estimate of the tag location. ...
Article
In this study, an autonomous underwater vehicle (AUV) was used to test this technology as a viable tool for directly observing the behaviour of marine animals and to investigate the behaviour, habitat use and feeding ecology of white sharks Carcharodon carcharias near Guadalupe Island off the coast of Mexico. During the period 31 October to 7 November 2013, six AUV missions were conducted to track one male and three female C. carcharias, ranging in estimated total length (LT) from 3·9 to 5·7 m, off the north-east coast of Guadalupe Island. In doing so, the AUV generated over 13 h of behavioural data for C. carcharias at depths down to 90 m. The sharks remained in the area for the duration of each mission and moved through broad depth and temperature ranges from the surface to 163·8 m depth (mean ± s.d. = 112·5 ± 40·3 m) and 7·9–27·1° C (mean ± s.d. = 12·7 ± 2·9° C), respectively. Video footage and AUV sensor data revealed that two of the C. carcharias being tracked and eight other C. carcharias in the area approached (n = 17), bumped (n = 4) and bit (n = 9) the AUV during these tracks. This study demonstrated that an AUV can be used to effectively track and observe the behaviour of a large pelagic animal, C. carcharias. In doing so, the first observations of subsurface predatory behaviour were generated for this species. At its current state of development, this technology clearly offers a new and innovative tool for tracking the fine-scale behaviour of marine animals.
... Acoustic telemetry traditionally depended on the recovery of submerged acoustic receivers or their interrogation by modems, but data can now be telemetered via satellite from remote locations, such as anchored or drifting buoys (13) or cabled underwater arrays. Most recently, acoustic receivers have been deployed on large animal carriers (e.g., seals) (14) and on ocean gliders, providing mobile platforms to detect tagged animals; autonomous underwater vehicles can even actively follow them (15). ...
Article
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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.
... Autonomous underwater vehicles equipped with telemetry devices are a maturing technology, and their ability to perform multiple sampling tasks with high spatial and temporal frequency complement existing telemetry sampling strategies (Grothues et al. 2008). This study is among the first to show that an AUV, integrated with acoustic receiver technology, can be used to detect in situ marine organism habitat selection (see Grothues et al. 2008, Clark et al. 2013. The AUV mission occurred during the peak migration of sand tigers in the Delmarva coastal ocean. ...
Article
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Quantifying habitat selection in marine organisms is challenging because it is difficult to obtain species location information with multiple corresponding habitat measurements. In the ocean, habitat conditions vary on many spatiotemporal scales, which have important consequences for habitat selection. While macroscale biotic and abiotic features influence seasonal movements (spatial scales of 100−1000 km), selectivity of conditions on mesoscales (1−100 km) reflects an animal’s response to the local environment. In this study, we examined habitat selectivity by pairing acoustic telemetry with environmental habitat parameters measured by an autonomous underwater vehicle (AUV), and demonstrate that migrating sand tiger sharks Carcharias taurus along the East Coast of the USA did not randomly use the coastal environment. Of the variables examined, we found evidence to suggest that sand tigers were selecting their habitat based on distance to shore, salinity, and colored dissolved organic matter (CDOM). Notably, temperature was not predictive of habitat use in our study. We posit that during their coastal migration, sand tigers select for specific mesoscale coastal habitats that may inform navigation or feeding behaviors. To our knowledge, this is the first empirical measure of mesoscale habitat selection by a coastal marine organism using an AUV. The applications of this method extend beyond the habitat selectivity of sand tigers, and will prove useful for future studies combining in situ observations of marine habitats and animal observations.
... The alternative is to tag and track large animals in the wild, which is challenging and rarely done (Watanabe and Takahashi, 2013). Recently, however, autonomous underwater vehicles have been used to track tagged leopard sharks, which is a very promising technique for future research (Clark et al., 2013). Our laboratory setup included an extremely large tank, thus facilitating this type of experiment. ...
... [10]. Clark et al. was successful in tracking tagged leopard sharks using a stereo-hydrophone system [11], [12]. Other researchers have automated visual extraction of marine animals from a video sequence, without closing servo loops. ...
Article
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This paper describes the use of a Remotely Operated Vehicle (ROV) equipped with a monocular vision system to find and track the squid Euprymna scolopes, so that motion behaviors of the squid could be characterized through the use of off-line image processing and state estimation. The ROV was deployed for several nights at several nearshore locations off Oahu, resulting in 10 hours of squid footage. Using blob-tracking image processing techniques and a Particle Filter state estimator, the squid can be detected and tracked. The position, velocity, and acceleration of the squid relative to the stationary ROV can be determined. Experiment results from tracking a simulated squid at known positions in a swimming pool and tracking of live squid in the ocean validate the performance of the tracking system. Results show the 3-D trajectory of the squid in a test feeding video. To the best of the authors' knowledge, this is the first observation and tracking of this species of squid in its natural environment.
... Equally, they have enabled explorations in complex underwater situations that are exceedingly dangerous, and sometimes practically impossible, for human researchers to go. For instance, AUVs have enabled explorations under exceedingly long arctic ice sheets and tracking of aquatic predators (including numerous species of sharks for example) (see Wadhams et al. 2006;Clark et al. 2013). ...
Article
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Environmental scientists and engineers have been exploring research and monitoring applications of robotics, as well as exploring ways of integrating robotics into ecosystems to aid in responses to accelerating environmental, climatic, and biodiversity changes. These emerging applications of robots and other autonomous technologies present novel ethical and practical challenges. Yet, the critical applications of robots for environmental research, engineering, protection and remediation have received next to no attention in the ethics of robotics literature to date. This paper seeks to fill that void, and promote the study of environmental robotics. It provides key resources for further critical examination of the issues environmental robots present by explaining and differentiating the sorts of environmental robotics that exist to date and identifying unique conceptual, ethical, and practical issues they present.
... Similarly, the direction in which each bearing measurement changes, relative to the known change in heading, can be used [18]. More computationally intensive approaches that resolve the bearing ambiguity as part of the target state estimation problem, for example, by using a particle filter [4], have also been demonstrated. In some studies, it is assumed that resolving the bearing ambiguity is a task completed by an intelligent sonar sensor-after detecting a target, the vehicle makes a right-angle turn and waits until the sensor reports that the bearing ambiguity has been cleared [5]. ...
Article
In this paper, we describe an unmanned underwater vehicle (UUV) behavior designed to track nearby vessels using bearing-only measurements obtained from a rigidly mounted planar hydrophone array—one that was originally designed for active sonar use but is repurposed for passive sonar use. Upon detecting a target, a maneuver is executed to resolve the port/starboard bearing ambiguity. The maneuver is heuristically designed with the aim of reducing the effects of end-fire, self-noise during maneuvers, and other noise/spurious measurements on the bearing ambiguity decision. After resolving the bearing ambiguity, the vehicle continuously adjusts its heading to track the target by keeping it broadside to the array. The performance of this behavior, as well as that of the passive sonar itself, is evaluated through field trials in the approaches to Boston Harbor using a Bluefin-21 UUV. In total, 19 successful behavior tests are described where the UUV resolves the bearing ambiguity and tracks either a static source emitting a predefined waveform or the platform noise of a medium-sized catamaran underway.
... Finally, single-beacon localization using autonomous vehicles as a moving landmark can also be used for target positioning and tracking in large areas without the fixed beacons' constraints. As an example, in Clark et al. (2013) a method was presented for tracking and following a tagged Leopard shark. ...
Article
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Underwater localization using acoustic signals is one of the main components in a navigation system for an autonomous underwater vehicle (AUV) as a more accurate alternative to dead-reckoning techniques. Although different methods based on the idea of multiple beacons have been studied, other approaches use only one beacon, which reduces the system’s costs and deployment complexity. The inverse approach for single-beacon navigation is to use this method for target localization by an underwater or surface vehicle. In this paper, a method of range-only target localization using a Wave Glider is presented, for which simulations and sea tests have been conducted to determine optimal parameters to minimize acoustic energy use and search time, and to maximize location accuracy and precision. Finally, a field mission is presented, where a Benthic Rover (an autonomous seafloor vehicle) is localized and tracked using minimal human intervention. This mission shows, as an example, the power of using autonomous vehicles in collaboration for oceanographic research.
... Nevertheless, the investigations are again limited to large animals due to the size of electronic tags (22). Other authors use bearing-only techniques to avoid the use of acoustic modems and overcome the size limitations (23,24), where an AUV borne hydrophones' array is used to track acoustic tags. Unfortunately, a substantial localization uncertainty is produced by the too-close positioning of hydrophones, which often requires larger separation that is not achievable on AUVs (25). ...
Article
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.
... Autonomous surface vehicles (ASVs) and autonomous underwater vehicles (AUVs) are becoming more common telemetry assets as receivers can be attached as a payload, or they can be integrated for real-time detection while simultaneously measuring physical and biological properties of the aquatic environment [7,8]. For example, robotic sailboats were used to carry acoustic receivers to quantify the spatial distribution of fishes [9], buoyancydriven gliders with integrated or externally mounted receivers have been used to study sturgeon and shark habitats [10][11][12], stereo-hydrophone acoustic receiver systems have been integrated into propelled AUVs to track and follow leopard sharks [13], and receivers and hydrophones have also been externally mounted and integrated into a propeller-driven AUV [14] and a wave glider for real-time detections of tagged marine life [15]. ...
Article
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Background Autonomous underwater vehicles (AUVs) and animal telemetry have become important tools for understanding the relationships between aquatic organisms and their environment, but more information is needed to guide the development and use of AUVs as effective animal tracking platforms. A forward-facing acoustic telemetry receiver (VR2Tx 69 kHz; VEMCO, Bedford, Nova Scotia) attached to a novel AUV (gliding robotic fish) was tested in a freshwater lake to (1) compare its detection efficiency (i.e., the probability of detecting an acoustic signal emitted by a tag) of acoustic tags (VEMCO model V8-4H 69 kHz) to stationary receivers and (2) determine if detection efficiency was related to distance between tag and receiver, direction of movement (toward or away from transmitter), depth, or pitch. Results Detection efficiency for mobile (robot-mounted) and stationary receivers were similar at ranges less than 300 m, on average across all tests, but detection efficiency for the mobile receiver decreased faster than for stationary receivers at distances greater than 300 m. Detection efficiency was higher when the robot was moving toward the transmitter than when moving away from the transmitter. Detection efficiency decreased with depth (surface to 4 m) when the robot was moving away from the transmitter, but depth had no significant effect on detection efficiency when the robot was moving toward the transmitter. Detection efficiency was higher when the robot was descending (pitched downward) than ascending (pitched upward) when moving toward the transmitter, but pitch had no significant effect when moving away from the transmitter. Conclusion Results suggested that much of the observed variation in detection efficiency is related to shielding of the acoustic signal by the robot body depending on the positions and orientation of the hydrophone relative to the transmitter. Results are expected to inform hardware, software, and operational changes to gliding robotic fish that will improve detection efficiency. Regardless, data on the size and shape of detection efficiency curves for gliding robotic fish will be useful for planning future missions and should be relevant to other AUVs for telemetry. With refinements, gliding robotic fish could be a useful platform for active tracking of acoustic tags in certain environments.
... Real-time satellite tracking is becoming more achievable even for smaller animals, although it remains costly. Underwater tracking has been accomplished with large coordinated networks of acoustic and radio frequency sensors and, for larger animals, with boats or autonomous underwater vehicles (Clark et al. 2013, Hussey et al. 2015, Lennox et al. 2017. Further, new tags can collect secondary information useful for elucidating interspecific interactions. ...
Article
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Migrations of diverse wildlife species often converge in space and time, with their journeys shaped by similar forces (i.e. geographic barriers and seasonal resources and conditions); we term this ‘co‐migration’. Recent studies have illuminated multi‐speciesmigrations by land and sea including the simultaneous movements of numerous insects, birds, bats and of fish invertebrates marine predators. Beyond their significance as natural wonders, species with overlapping migrations may interact ecologically, with potential effects on population and community dynamics. Direct and indirect ecological interactions (including predation and competition) between migrant species remain poorly understood, in part because migration is the least‐studied phase of animals’ annual cycles. To address this gap, we conducted a literature review to examine whether animal migration studies incorporate multiple species and to what extent they investigate interspecific interactions between co‐migrants. Following a key word search, we read all migration research papers in 23 relevant peer‐reviewed journals during 2008–2017. Thirty percent of animal migration papers reported two or more species with coinciding migrations, suggesting that co‐migrations are common, although few studies investigated or discussed these mixed‐species migrations further. Synthesizing these, we present examples and describe five types of ecological interactions between migrating species, including predator–prey, host–parasite and commensal relationships. Considering migratory animals as interacting with migrant communities will enhance understanding of the drivers of migration and could improve predictions about wildlife responses to global change. Further research focused on multi‐species migrations could also inform conservation efforts for migratory animal populations, many of which are declining or shifting, with unexplored consequences for other co‐migratory species.
... The AUV was used to measure water quality parameters that provide indicators of algal activity, temperature, conductivity, pH, dissolved oxygen, turbidity, total chlorophyll and phycocyanin fluorescence. In [30], the authors developed an AUV system able to track a leopard shark tagged with an acoustic Lotek MM Series transmitter along the SeaPlane Lagoon (Los Angeles, USA). The AUV was fitted with a stereo-hydrophone and receiver system able to detect acoustic signals. ...
... Other developments are tags that combine acoustic and radio telemetry and the addition of sensors that measure for instance temperature, depth or muscle activity and transmit the measured values together with each transmission (Hockersmith and Beeman, 2012). One of the most recent developments is the use of autonomous underwater vehicles (AUV) to follow tagged animals (Clark et al., 2013;Kumar et al., 2018). ...
Thesis
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Migrating fish populations are of high ecological and economical importance, but they are heavily threatened by human impacts and declined sharply in the last decades. Habitat fragmentation is one of the main threats to migrating fish: dams, weirs, hydropower and pumping stations, sluices and navigation locks hamper migration in upstream and downstream direction. Historically, research has mainly focused on solving upstream migration barriers, while downstream migration has been addressed only more recently. Understanding fish behaviour at barriers is essential to find solutions for downstream migrating fish. In the last decades, technological advancements in fish tracking have enlarged the possibilities to gather knowledge on fish behaviour during downstream migration, especially in relation to hydrodynamics. Moreover, the increase in computer calculation power allowed simulating these hydrodynamics by the use of Computational Fluid Dynamics (CFD). This thesis research aimed to better understand the impact of navigation locks on downstream migrating fish and the mechanisms behind the migration failures and delays previously observed in the Albert Canal, hence contributing to the general knowledge and understanding of downstream fish migration issues. Therefore, we tracked downstream migrating silver eels (Anguilla anguilla) and salmon smolts (Salmo salar), tagged with acoustic transmitters, in the canal pound and area just upstream of the navigation lock complex of Kwaadmechelen. Additionally, we investigated the methodological aspects of studying fish behaviour with acoustic telemetry, by studying different positioning and filtering methods and by conducting a sensitivity (simulation) study on the YAPS (Yet Another Positioning Systems) algorithm. Currently, neither the Meuse River nor the Albert Canal can guarantee free fish migration from the Meuse basin to the sea. Restoring the route through the Meuse would probably be most successful, both from a hydrodynamic and from an ecological point of view. Nevertheless, deviation of a part of the migrating population to the Albert Canal is probably unavoidable. Moreover, in other situations an alternative route to avoid navigation locks might not be available. This thesis showed that navigation locks delay or even stop downstream fish migration due to disorientation of the fish near and in the ship lock complexes, failure to pass, induction of searching behaviour and most probably also injury and mortality. Given the increase in construction and renovation of navigation locks worldwide, the pursuit of fish-friendly navigation locks will be essential to guarantee downstream fish migration.
... In [3], the authors also use AUVs in order to track and follow fish. In this case the fish (tiger shark) tag includes an acoustic pinger that allows AUVs to estimate the relative angle between AUV and fish while underwater. ...
Conference Paper
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This paper describes scientific and engineering efforts towards remote sensing, tagging and continuous tracking of sunfish specimens (Mola mola, world largest bony fish) in the open sea. This ongoing experiment is done in the context of a collaboration between MBARI and Porto University and bridges biology, fisheries research, autonomy and control with use of satellite tags, autonomous aerial, surface and underwater vehicles, as well as new software tools for remote asset control and situational awareness. Here we describe technologies and overall architecture of the experiment and results from initial deployments.
... We are, however, unaware of any aerial system that has been developed to the point where it can autonomously track an animal at sea. AUV based systems have also been developed to automatically detect and follow specific underwater signals (e.g., Clark et al., 2013) with pinging transponders (Section 5.4) either attached to other vehicles or to fish. We are similarly unaware of any system that can track vocalising animals using passive acoustics. ...
Article
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Recent technology developments have turned present-day unmanned systems into realistic alternatives to traditional marine animal survey methods. Benefits include longer survey durations, improved mission safety, mission repeatability, and reduced operational costs. We review the present status of unmanned vehicles suitable for marine animal monitoring conducted in relation to industrial offshore activities, highlighting which systems are suitable for three main monitoring types: population, mitigation, and focal animal monitoring. We describe the technical requirements for each of these monitoring types and discuss the operational aspects. The selection of a specific sensor/platform combination depends critically on the target species and its behaviour. The technical specifications of unmanned platforms and sensors also need to be selected based on the surrounding conditions of a particular offshore project, such as the area of interest, the survey requirements and operational constraints.
... Additionally, AUVs contain built-in software that allows real-time modifications to preprogrammed routes through external input to avoid potential threats (e.g., ships or sea ice). Using this software, researchers were able to track the movements of a tagged leopard shark (Triakis semifasciata) autonomously over several hours using tag transmissions received by a directional hydrophone attached to an AUV (Lotek MAP600RT) as navigational input (Clark et al., 2013). The development of a custom AUV (iSAT) aims to use a similar approach to track large-scale whale shark (Rhincodon typus) movements in the Red Sea while transmitting GPS locations to ARGOS satellites in real time (Llewellyn, 2012). ...
Article
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.
Article
Currently, individual animal movement data can be obtained using a variety of methods, but each methodology is limited in either temporal or spatial resolution. A new method of active tracking was developed which utilizes autonomous underwater vehicles (AUV) equipped with stereo-hydrophones that can accurately estimate the position of a moving acoustic tag, while remaining at a distance. This technology was tested and compared to standard human-based active tracking technology to understand the benefits and limitations of this new technique. An AUV and a researcher independently tracked stationary and moving targets of known location in order to compare their spatial and temporal accuracy. Both methods were then used to track a leopard shark, Triakis semifasciata, in the field. The autonomous vehicle accurately positioned both stationary and moving tags with a positional error of < 10 m. For stationary transmitters, the AUV and the researcher were comparable, but when tracking moving transmitters, the AUV had significantly better spatial accuracy. Throughout all trials, the AUV had a higher frequency of accurate location estimates than a researcher actively tracking. Based on these findings, the AUV was able to more accurately track and record the position of an acoustically tagged shark in the field. Using this new technology, researchers should be able to maintain or improve the spatial resolution of measurements when actively tracking acoustically tagged individuals and will be able to increase the temporal resolution of measurements while minimizing the potential influence of tracking on the behavior of the animal.
Chapter
1. Introduction 1.1. Early Field Physiology1.2. Importance of Linking Laboratory and Field Work1.3. Biotelemetry and Biologging2. Thermal Physiology 2.1. Thermal Biology in the Lab2.2. Thermal Biology in the Field2.3. Behavioral Thermoregulation2.4. Thermal Refuging2.5. Physiological Thermoregulation2.6. Thermal Effect on Metabolic Rate3. Swimming Kinematics and Energetics 3.1. Swimming3.2. Heart Rate3.3. Feeding and Digestion4. A Case Field Study: Thresher Sharks 4.1. The Role of the Caudal Fin4.2. RM Morphology4.3. RM Uncoupling and Swimming Mode4.4. RM Endothermy and Thermal Distributions5. Future Directions in Field PhysiologyThis chapter reviews how field work with elasmobranchs offers an important complement to laboratory studies, and highlights examples of when going to the field is the only, and most often the best, option to work with species that are large, elusive, or cannot be held in captivity. We begin by offering a brief summary of the pioneering work in shark field physiology (ca. 1960), the technologies used to track and log physiological data in the field, and how field work can expand and enhance the knowledge gained in the laboratory. The chapter then proceeds to offer a more detailed account of how field and laboratory work have offered a better understanding of the thermal biology of sharks and rays, and provides examples of work showing the use of behavior and some of the physiological mechanisms that elasmobranchs can utilize to alter the rates of key physiological parameters. Because most sharks and rays are highly mobile, we then address how field work has been used to study their swimming kinematics, bioenergetics, and their feeding ecology. This is followed by a case study on how field work has given an unprecedented glimpse into the biology, ecology, and physiology of the thresher sharks, a unique group of sharks for which most prior information was obtained from dead specimens that were captured incidentally by fishermen. While the logistical difficulties surrounding field work with sharks and rays has often lead to scenarios where only a few specimens were studied, the development of new and lower cost technologies and the use of better techniques for handling sharks in the wild will allow the recording of more physiological and environmental variables and allow access to a higher number of species, even in places thought to be inaccessible in the past.
Conference Paper
Autonomous Underwater Vehicles (AUV) maintain their location information during navigation in order to reach a pre-determined destination. Most of previous underwater localization approaches assume that all AUVs are within one hop, which severely restricts the scale of the AUVs. In this paper, we localize AUVs in a multihop Mobile Underwater Wireless Network (MUWN) via surfacing a 3-dominating set of AUVs as beacons. Our scheme surfaces only beacon AUVs to obtain accurate location information from external sources such as satellites, then localizes the remaining AUVs as reference. Simulation result shows that our scheme greatly improves energy efficiency, security against detection and localization accuracy.
Chapter
Marine robots communicating wirelessly is an increasingly attractive means for observing and monitoring the ocean, but acoustic communication remains a major impediment to real-time control. In this paper we address through experiments the capability of acoustics to sustain highly dynamic, multi-agent missions, in particular range-only pursuit in a challenging shallow-water environment. We present in detail results comparing the tracking performance of three different communication configurations, at operating speeds near 1.5 m/s. A “lower bound” case with RF wireless communication, a 4-second cycle and no quantization has a tracking bandwidth of \(\approx \)0.5 rad/s. When using full-sized modem packets with negligible quantization and a 23-second cycle time, the tracking bandwidth is \(\approx \)0.065 rad/s. With 13-bit mini-packets, we employ logarithmic quantization to achieve a cycle time of 12 s and a tracking bandwidth of \(\approx \)0.13 rad/s. These outcomes show definitively that aggressive dynamic control of multi-agent systems underwater is tractable today.
Article
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Robotics technologies are being used for environmental research, and engineers and ecologists are exploring ways of integrating an array of new robots into ecosystems as a means of responding to mounting environmental problems. These efforts introduce new roles that robots may play in our environments, potentially crucial new forms of human dependence on such robots, and new ways that robots can promote and enhance well-being. Such approaches at once bring up questions about when the use of robots for repairing or mitigating ecological problems is ethically permissible and when it is not. This article builds on recent work on the ethics of such ‘environmental robots’, and advances a virtue-centred framework for guiding the development and use of robots for environmental engineering and for addressing ecological justice issues.
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Underwater image enhancement is such an important vision task due to its significance in marine engineering and aquatic robot. It is usually work as a pre-processing step to improve the performance of high level vision tasks such as underwater object detection. Even though many previous works show the underwater image enhancement algorithms can boost the detection accuracy of the detectors, no work specially focus on investigating the relationship between these two tasks. This is mainly because existing underwater datasets lack either bounding box annotations or high quality reference images, based on which detection accuracy or image quality assessment metrics are calculated. To investigate how the underwater image enhancement methods influence the following underwater object detection tasks, in this paper, we provide a large-scale underwater object detection dataset with both bounding box annotations and high quality reference images, namely OUC dataset. The OUC dataset provides a platform for researchers to comprehensive study the influence of underwater image enhancement algorithms on the underwater object detection task.
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In this paper, the trajectory tracking control of the autonomous underwater vehicle (AUV) has been investigated in discrete time, for ease of digital computer calculation. A reinforcement learning scheme is employed using two neural networks, whereas the first one is to compensate for uncertainties for the controller, and the second one is to estimate the evaluation function, such that optimal tracking performance could be achieve for the AUV. Simulation results show that the errors convergence to a adjustable neighborhood around zero, and optimization has been achieved in the sense of reinforcement learning.
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Autonomous underwater vehicles (AUVs) have demonstrated superior performance for tracking marine animals tagged with individually coded acoustic transmitters. However, AUVs engaged in mapping the distribution of multiple tagged fish have not previously been able to alter search paths to achieve precise position estimates. This problem is solved by the development of payload control software (Synthetic Aperture Override, SAOVR) that allows the AUV to maneuver with trajectories favorable for solving the tag's location from a synthetic aperture. Upon tag detection during a default mission search path, SAOVR (running on an embedded guest computer) seeks permission to take over navigation from the vehicle's native system after checking constraints of geography, timing, tag identification, signal strength, and current navigation state. Permitted maneuvers are then chosen from a template library and executed before returning the AUV to the point of first deviation for continued searching of other tags. Field evaluation on moored reference tags showed a high level of predictability in the AUV's behavior at SAOVR initiation and through maneuvers. Trials suggest that this logic system is highly beneficial to AUV use for fish telemetry in challenging environments such as narrow, deep fjords, or among reefs. Any mission programmed with the AUV's native software can be run with the SAOVR package to allow scientists to easily implement and manipulate synthetic aperture geometries without altering any of the software. Further modeling can help improve template design specific to expected movements of different fish species and relative to the designation of signal strength‐defined execution thresholds.
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Marine and land plastic debris biodegrades at micro- and nanoscales through progressive fragmentation. Oceanographic model studies confirm the presence of up to ∼2.41 million tons of microplastics across the Atlantic, Pacific, and Indian subtropical gyres. Microplastics distribute from primary (e.g., exfoliating cleansers) and secondary (e.g., chemical deterioration) sources in the environment. This anthropogenic phenomenon poses a threat to the flora and fauna of terrestrial and aquatic ecosystems as ingestion and entanglement cases increase over time. This review focuses on the impact of microplastics across taxa at suggested environmentally relevant concentrations, and advances the groundwork for future ecotoxicological-based research on microplastics including the main points: (i) adhesion of chemical pollutants (e.g., PCBs); (ii) biological effects (e.g., bioaccumulation, biomagnification, biotransportation) in terrestrial and aquatic organisms; (iii) physico-chemical properties (e.g., polybrominated diphenyl ethers) and biodegradation pathways in the environment (e.g., chemical stress, heat stress); and (iv) an ecotoxicological prospect for optimized impact assessments.
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Denizlerin önemi; ülkelerarası mal taşımacılığının önemli bir yüzdesiyle, deniz canlıları ticaretiyle, denizlerden çıkarılan petrol ve doğalgaz gibi son derece stratejik ürünlerle ilgili olduğu kadar turizm endüstrisiyle de ilgilidir. Jeopolitik bakımdan çok kritik bir konumda olan ülkemiz içinse, çevre denizlerimiz son yıllarda ‘Mavi Vatan’ olarak tanımlanmaktadır ve bu kavramın içeriğinde turizm de olmalıdır. ‘Deniz turizmi’ ve dolayısıyla ‘deniz turizmi işletmeciliği’ kavramları aslında turizmin başlıca unsurlarındandır. Daha ötesinde denizle ilgili hemen her şey, tatil turizminin doğrudan öznesi durumundadır. Oysa Türkiye deniz turizmi özelinde, deniz turizmi işletmeciliğinin akademisyenler dâhil tüm turizm paydaşlarınca ikinci planda bırakıldığını ve gereği kadar önemsenmediğini ileri sürmek mümkündür. Türkiye gibi söylemde üç tarafı denizlerle çevrili ve incoming (karşılayıcı) turizm pazarında dünyanın önde gelen ülkelerinden biriyseniz, deniz turizmi bileşenlerinde de iddialı olmanız gerekir. Örneğin lüks turizm unsurlarından kurvaziyer turizminde Türkiye ne kadar başarılıdır? Kaç işletmenin ne kadar kurvaziyer gemisi, hangi pazarlarda hizmet vermektedir? Yatçılıkla ve marinacılıkla ilgili rakipleriniz olan diğer Akdeniz ülkeleriyle kıyasladığınızda konumunuz nedir? Hepsinden daha dramatik olanı da 1980’li yılların sonlarına kadar hem Karadeniz’de hem de Ege ve Akdeniz’de şehirlerarası yolcu taşımacılığı yapan Karadeniz, Akdeniz, Ege ve İzmir gibi gemilerin de seferleri kârlı olmadıkları gerekçesiyle sonlandırılmıştır. Hâlbuki kendi çocukluğumdan hatırladığım kadarıyla, İstanbul’dan Trabzon’a Ege vapuruyla yaptığımız ve iki günden fazla süren yolculuklar gerek aktiviteleri bakımından gerekse farklı insanlarla tanışma vb. bakımlarından kimi zaman destinasyonun kendisinden daha eğlenceli olabiliyor, gelecek için hafızlarda güzel anılar bırakabiliyordu. Ayrıca günümüzdeki iç turizm kültür turlarının popülerliği de hesaba katılırsa insanların örneğin Karadeniz turlarında farklı limanlara uğrayarak şehirleri gezmeleri önemli bir alternatif pazar oluşturabilir. Hele hele de günümüzdeki otobüs, midibüslerle yapılan ve adeta koşturmaca-yorgunlukla geçen kültür turlarıyla kıyaslanırsa, vakti olan turistler için gemi turlarının kesinlikle tercih sebebi olacağı açıktır.
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This paper provides a systematic state of the art review on tracking the fine scale movements of fish with the use of autonomous maritime robotics. Knowledge of migration patterns and the localization of specific species of fish at a given time is vital to many aspects of conservation. This paper reviews these technologies and provides insight into what systems are being used and why. The review results show that a larger amount of complex systems that use a deep learning techniques are used over more simplistic approaches to the design. Most results found in the study involve Autonomous Underwater Vehicles, which generally require the most complex array of sensors. The results also provide insight into future research such as methods involving swarm intelligence, which has seen an increase in use in recent years. This synthesis of current and future research will be helpful to research teams working to create an autonomous vehicle with intentions to track, navigate or survey.
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One of the main task for deep sea submersible is for human-machine collaborative scientific exploration, e.g., human ourselves drive the submersible and monitor cameras around the submersible to observe new species fish or strange topography in a tedious way. In this paper, by defining novel marine animals or any extreme events as novel events, we design a new deep sea novel visual event analysis framework to improve the efficiency of human-machine collaboration and improve the accuracy simultaneously. Specifically, our visual framework concerns diverse functions than most state-of-the-arts, including novel event detection, tracking and summarization. Due to the power and computation resource limitation of the submersible, we design an efficient deep learning based visual saliency method for novel event detection and propose an online object tracking strategy as well. All the experiments are depending on Chinese Jiaolong, the manned deep sea submersible, which mounts several PanCtiltCzoom (PTZ) camera and static cameras. We build a new novel deep sea event dataset and the results justify that our human-machine collaborative visual observation framework can automatically detect, track and summarize the novel deep sea event.
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Coastal elasmobranchs such as the shovelnose guitarfish (Rhinobatos productus) seasonally use bays and estuaries for mating, pupping and feeding. However, many human-populated coastal areas have been developed, making them unavailable to coastal fish populations. The Full Tidal Basin (FTB) of the Bolsa Chica Ecological Reserve, California, USA, was completed in 2006, with the aim to restore lost estuarine habitat in southern California. Monthly abundance surveys conducted inside the FTB between June 2008 and September 2009 showed that shovelnose guitarfish were present throughout the year. Over 96% of the individuals caught were juveniles and these were most abundant in waters between 208C and 248C. Concurrently, 23 shovelnose guitarfish were fitted with coded acoustic transmitters and continuously tracked within the FTB for 16 months. Telemetry data showed individuals remained inside the FTB for, on average, 73.9 days (range 15–172 days), and made few movements between the FTB and the ocean. Tagged individuals disproportionately used mud habitats and waters at temperatures of 228C, both of which are more common in the FTB than the neighbouring coastal ocean. The present study examined the structure and functionality of a restored estuary and suggests that the FTB is important habitat for a benthic predator, a promising result three years after restoration.
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Presented is a method for estimating the 2D planar position, velocity, and orientation states of a tagged shark. The method is designed for implementation on an Autonomous Underwater Vehicle (AUV) equipped with a stereo-hydrophone and receiver system that detects acoustic signals transmitted by a tag. The particular hydrophone system used here provides a measurement of relative bearing angle to the tag, but does not provide the sign (+ or -) of the bearing angle. A Particle Filter was used for fusing these measurements over time to produce a state estimate of the tag location. The Particle Filter combined with an active control system allowed the system to overcome the ambiguity in the sign of the bearing angle. This state estimator was validated by tracking both a stationary tag and moving tag with known positions. These experiments revealed state estimate errors were on par with those obtained by manually driven boat based tracking systems, the current method used for tracking fish and sharks over long distances. Final experiments involved the catching, releasing, and an autonomous AUV tracking of a 1 meter Leopard Shark (Triakis semifasciata) in SeaPlane Lagoon, Los Angeles, California.
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Home range, activity patterns, site fidelity and habitat preference of the kelp bass Paralabrax clathratus were determined from 12 adult fish tracked using acoustic telemetry within a temperate no-take marine reserve (0.13 km(2)). Home range sizes ranged from 33 to 11224 m(2), averaging 3349 +/- 3328 m(2) (+/-SD), but did not correlate with fish size. Fish were active and occupied similar-sized activity spaces during both day and night. Kelp bass exhibited a high degree of site fidelity, remaining resident in core areas for up to 3 yr. Relative to the total amount of available habitat, kelp bass showed a habitat selection preference for rock boulder, rock rubble and kelp habitat. These habitats offer high vertical relief, shade and large holes for shelter, and may attract and facilitate prey capture. Average home range size was 3 % of the area of the reserve. Only 1 of 12 tracked fish crossed the reserve boundary, but this accounted for less than 5 % of the fish's time. Natural habitat breaks along the reserve boundary may have further limited adult kelp bass movements. The small home ranges and high site fidelity of kelp bass in this reserve indicate that the reserve is effective in protecting the resident adult stock.
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A general method for analysis of movement data from tag returns is proposed which has four major components: (1) a population dynamics and movement model that describes how the number of tagged individuals in each spatial location changes over time; (2) an observation model which describes how the tags are recovered and reported; (3) a likelihood function that specifies the likelihood of observing a specific number of recoveries in each space/time stratum as a function of the number thought to be there under a specific set of parameters of the population dynamics, movement and observation models, and (4) a nonlinear function minimization computer algorithm. This approach is applied to movements of skipjack tuna (Euthynnus pelamis). When tagging and recapture take place in each spatial stratum, reliable estimates of movement rates can be obtained. The approach described is completely general and can be used in cases where movement takes place continuously, or only once in the life history. Methods for determining confidence limits and evaluation of residuals are presented and extensions that include tagging mortality, tag shedding, and size specific vulnerability are discussed.
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The fishery for California groundfishes is managed using broad species complexes, although some non-groundfish species are managed similarly due to the perception of shared behavioral characteristics. This study integrates acoustic telemetry and a GIS to quantify movement patterns of one such species, the ocean whitefish (Caulolatilus princeps) in a marine protected area. Seventeen ocean whitefish were tagged and actively tracked over multiple 24-h periods to measure fine-scale movement patterns. Home ranges based on 95% kernel utilization distributions averaged 20,439 ± 28,492 (±S.D.) m 2 . Fish were active during the day, foraging over sand habitat at depths averaging 21 ± 8 m, but were inactive at night, taking refuge near rocky reefs at depths averaging 15 ± 7 m. Seventeen additional fish were tagged with coded acoustic transmitters and passively tracked using automated underwater acoustic receivers for up to 1 year. Approximately 75% of these fish exhibited long-term (1 year) fidelity to home ranges in the study area. Results suggest that MPAs can be an effective means of protecting populations of ocean whitefish and based on their habitat associations, ocean whitefish can be managed separately from other reef associated groundfishes.
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Remotely sensed tracking data collected on animal movement is vastly un-derutilized due to a lack of statistical tools for appropriate analysis. Features of such data that make analysis particularly challenging include the presence of estimation errors that are non-Gaussian and vary in time, observations that occur irregularly in time, and com-plexity in the underlying behavioral processes. We develop a state–space framework that simultaneously deals with these features and demonstrate our method by analyzing three seal pathway data sets. We show how known information regarding error distributions can be used to improve inference of the underlying process(es) and demonstrate that our frame-work provides a powerful and flexible method for fitting different behavioral models to tracking data.
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The California sheephead, Semicossyphus pulcher Ayres (Labridae), is a carnivorous, temperate, rocky-reef/kelp-bed species that is highly sought in recreational and commercial fisheries. Fine-scale acoustic telemetry tracking was used to ascertain the home range and habitat utilization of S. pulcher. Sixteen adult S. pulcher (26–38cm SL) were surgically fitted with small acoustic transmitters and manually tracked for up to 144h during multiple, 24-h periods between March 2001 and August 2002 within the Catalina Marine Science Center Marine Life Reserve (3326N; 11829W). A geographic information system was used to calculate home range sizes (95% kernel utilization distributions) and habitat use. Tracking of the first five fish over 24h confirmed that S. pulcher were strictly diurnal, so the remaining 11 fish were tracked from 1h before sunrise to 1h after sunset. Home ranges varied greatly, from 938 to 82,070m2, with a mean (SD) of 15,13426,007m2. Variability in home range sizes among fish was attributed to differences in habitat shape (embayment vs. contiguous coastline) and to natural habitat boundaries (deep, sandy expanses) in adjacent areas within the reserve. There was a significant relationship between fish length and proportion of time spent in different habitats (sand vs. reef). S. pulcher were found within rocky-reef areas 54% of the time, and, within these areas, a greater percentage of daytime was spent in high-relief areas. Based on the relatively small size and persistence of home ranges of adult S. pulcher, no-take reserves, if they contain appropriate habitat, would provide adequate protection for their stocks.
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Sharks were among the first marine animals to carry telemetry systems because of their size and the need to understand their interactions with humans. Modern telemetry systems can gather many kinds of data (limited only by imagination, funding and sensor types), indicating which animals are near telemetry receivers and what they are doing. Receivers now range from simple autonomous detector units for deployment in mid-water in large-scale grids, to sophisticated automated benthic recorders, to triangulating radio-linked buoy systems (RAP), to ship-borne transponders. In addition, archival tags can now gather and store data even while the shark is away, to be downloaded later. Older types had to be recovered, but popup tags release from sharks automatically, surface and transfer data to satellites, while CHAT tags download whenever queried by a nearby transponding acoustic receiver. Sophisticated animal-borne tags dramatically increase the information gathered about sharks and their environment. The examples provided show the parallel progression of shark biology and acoustic biotelemetry illustrating that telemetry systems are tools for gathering data, which can often be honed to facilitate biological experiments. Future visions include sensors that directly measure shark swimming power and cardiac output, compressing the data so that it can be delivered to RAP systems tracking multiple animals with meter resolution in near real time. CHAT tags as small as 22mm diameter should be able to return similar data from trips of hundreds of kilometers. Continued communication between biologists and engineers is essential to develop these technologies.
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Chemical and hydrological AUV sensors (e.g. C, T, 02, CDOM, Chlorophyll a) collect information about water in contact with or in close proximity to the vehicle. Sonar (e.g. ADCF, side scan, dual beam, and multibeam) collect data about features distant on the scale of tens of meters away and linked to coordinates. In contrast, acoustic tags implanted in fishes or other marine fauna can be detected at distances greater than a kilometer away, which brings special considerations to data treatment and merging. In the case of telemetry systems that log sound pressure levels, relative signal strength can be used to produce proximity maps using regression. For systems with invariant signal timing, a synthetic aperture engine can calculate location of the tag if a suitable AUV path produces a good aperture. In the common case where both of these conditions are lacking, the tag position must be assigned to a place along the vehicle's path. The use of tags that broadcast information from their own sensors (e.g. pressure, temperature) can help resolve both the position and environment of the distant tag. An empirically-fashioned hierarchical decision matrix based on numerous AUV-fish telemetry missions in shallow and deep (<;3m to 600m) water assists in mission planning, data processing, and displaying AUV-collected data about telemetered fauna and their environment.
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One of the goals in the field of mobile robotics is the development of mobile platforms which operate in populated environments. For many tasks it is therefore highly desirable that a robot can track the positions of the humans in its surrounding. In this paper we introduce sample-based joint probabilistic data association filters as a new algorithm to track multiple moving objects. Our method applies Bayesian filtering to adapt the tracking process to the number of objects in the perceptual range of the robot. The approach has been implemented and tested on a real robot using laser-range data. We present experiments illustrating that our algorithm is able to robustly keep track of multiple people. The experiments furthermore show that the approach outperforms other techniques developed so far.
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The evolution and improvement of novel applications on acoustic telemetry technology are driven mainly by the need to address more complex behavioral, ecological and physiological questions. A new Vemco VR2W Positioning System (VPS) is described and tested here using an array of 16 VR2W acoustic monitoring receivers and 8 fixed synchronizing transmitters. VPS positioning algorithm is based on the 3-receiver time-difference-of-arrival (TDOA) algorithm used by the existing Vemco VRAP system, extended to work with an array of three or more receivers that do not have synchronized clocks. The positional accuracy and performance of the VPS was estimated on a stationary and a slow-moving coded transmitter, and on two free-swimming elasmobranch species. Mean positional accuracy (±SD) of VPS estimates from a stationary transmitter deployed at several locations within the receiver array was 2.64 ± 2.32 m. Positional error was significantly lower inside (2.13 ± 1.31 m) than outsid
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Organisms respond to environmental heterogeneity at different scales and in different ways. These differences are consequences of how the movement characteristics of animals - their movement rates, directionality, turning frequencies, and turning angles - interact with patch and boundary features in landscape mosaics. The interactions of movement patterns with landscape features in turn produce spatial patterns in individual space-use, population dynamics and dispersion, gene flow, and the redistribution of nutrients and other materials. We describe several theoretical approaches for modeling the diffusion, foraging behavior, and population dynamics of animals in heterogeneous landscapes, including: (1) scaling relationships derived from percolation theory and fractal geometry, (2) extensions of traditional patch-based metapopulation models, and (3) individual-based, spatially explicit models governed by local rules. We conclude by emphasizing the need to couple theoretical models with empirical studie
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Determining individual-level interactions that govern highly coordinated motion in animal groups or cellular aggregates has been a long-standing challenge, central to understanding the mechanisms and evolution of collective behavior. Numerous models have been proposed, many of which display realistic-looking dynamics, but nonetheless rely on untested assumptions about how individuals integrate information to guide movement. Here we infer behavioral rules directly from experimental data. We begin by analyzing trajectories of golden shiners (Notemigonus crysoleucas) swimming in two-fish and three-fish shoals to map the mean effective forces as a function of fish positions and velocities. Speeding and turning responses are dynamically modulated and clearly delineated. Speed regulation is a dominant component of how fish interact, and changes in speed are transmitted to those both behind and ahead. Alignment emerges from attraction and repulsion, and fish tend to copy directional changes made by those ahead. We find no evidence for explicit matching of body orientation. By comparing data from two-fish and three-fish shoals, we challenge the standard assumption, ubiquitous in physics-inspired models of collective behavior, that individual motion results from averaging responses to each neighbor considered separately; three-body interactions make a substantial contribution to fish dynamics. However, pairwise interactions qualitatively capture the correct spatial interaction structure in small groups, and this structure persists in larger groups of 10 and 30 fish. The interactions revealed here may help account for the rapid changes in speed and direction that enable real animal groups to stay cohesive and amplify important social information.
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Impacts of chronic overfishing are evident in population depletions worldwide, yet indirect ecosystem effects induced by predator removal from oceanic food webs remain unpredictable. As abundances of all 11 great sharks that consume other elasmobranchs (rays, skates, and small sharks) fell over the past 35 years, 12 of 14 of these prey species increased in coastal northwest Atlantic ecosystems. Effects of this community restructuring have cascaded downward from the cownose ray, whose enhanced predation on its bay scallop prey was sufficient to terminate a century-long scallop fishery. Analogous top-down effects may be a predictable consequence of eliminating entire functional groups of predators.
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An optimal search theory, the so-called Lévy-flight foraging hypothesis, predicts that predators should adopt search strategies known as Lévy flights where prey is sparse and distributed unpredictably, but that Brownian movement is sufficiently efficient for locating abundant prey. Empirical studies have generated controversy because the accuracy of statistical methods that have been used to identify Lévy behaviour has recently been questioned. Consequently, whether foragers exhibit Lévy flights in the wild remains unclear. Crucially, moreover, it has not been tested whether observed movement patterns across natural landscapes having different expected resource distributions conform to the theory's central predictions. Here we use maximum-likelihood methods to test for Lévy patterns in relation to environmental gradients in the largest animal movement data set assembled for this purpose. Strong support was found for Lévy search patterns across 14 species of open-ocean predatory fish (sharks, tuna, billfish and ocean sunfish), with some individuals switching between Lévy and Brownian movement as they traversed different habitat types. We tested the spatial occurrence of these two principal patterns and found Lévy behaviour to be associated with less productive waters (sparser prey) and Brownian movements to be associated with productive shelf or convergence-front habitats (abundant prey). These results are consistent with the Lévy-flight foraging hypothesis, supporting the contention that organism search strategies naturally evolved in such a way that they exploit optimal Lévy patterns.
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We explored telemetry of transmitter tagged fishes from an autonomous underwater vehicle with a hydrophone/ datalogger processing code-division-multiple- access acoustic signals. Geolocation estimates used synthetic aperture and relative sound strength mapping. Signal reception patterns from tagged Atlantic sturgeon were similar to that of moored reference tags but those from tagged winter flounder were reduced in range due to burying behavior.
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Habitat selection processes in highly migratory animals such as sharks and whales are important to understand because they influence patterns of distribution, availability and therefore catch rates. However, spatial strategies remain poorly understood over seasonal scales in most species, including, most notably, the plankton-feeding basking shark Cetorhinus maximus. It was proposed nearly 50 yr ago that this globally distributed species migrates from coastal summerfeeding areas of the northeast Atlantic to hibernate during winter in deep water on the bottom of continental-shelf slopes. This view has perpetuated in the literature even though the 'hibernation theory' has not been tested directly. We have now tracked basking sharks for the first time over seasonal scales (1.7 to 6.5 mo) using 'pop-up' satellite archival transmitters. We show that they do not hibernate during winter but instead undertake extensive horizontal (up to 3400 km) and vertical (>750 m depth) movements to utilise productive continental-shelf and shelf-edge habitats during summer, autumn and winter. They travel long distances (390 to 460 km) to locate temporally discrete productivity 'hotspots' at shelf-break fronts, but at no time were prolonged movements into open-ocean regions away from shelf waters observed. Basking sharks have a very broad vertical diving range and can dive beyond the known range of planktivorous whales. Our study suggests this species can exploit shelf and slope-associated zooplankton communities in mesopelagic (200 to 1000 m) as well as epipelagic habitat (0 to 200 m).
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We present a framework for fitting multiple random walks to animal movement paths consisting of ordered sets of step lengths and turning angles. Each step and turn is assigned to one of a number of random walks, each characteristic of a different behavioral state. Behavioral state assignments may be inferred purely from movement data or may include the habitat type in which the animals are located. Switching between different behavioral states may be modeled explicitly using a state transition matrix estimated directly from data, or switching probabilities may take into account the proximity of animals to landscape features. Model fitting is undertaken within a Bayesian framework using the WinBUGS software. These methods allow for identification of different movement states using several properties of observed paths and lead naturally to the formulation of movement models. Analysis of relocation data from elk released in east-central Ontario, Canada, suggests a biphasic movement behavior: elk are either in an "encamped" state in which step lengths are small and turning angles are high, or in an "exploratory" state, in which daily step lengths are several kilometers and turning angles are small. Animals encamp in open habitat (agricultural fields and opened forest), but the exploratory state is not associated with any particular habitat type.
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We address the general question of what is the best statistical strategy to adapt in order to search efficiently for randomly located objects ('target sites'). It is often assumed in foraging theory that the flight lengths of a forager have a characteristic scale: from this assumption gaussian, Rayleigh and other classical distributions with well-defined variances have arisen. However, such theories cannot explain the long-tailed power-law distributions of flight lengths or flight times that are observed experimentally. Here we study how the search efficiency depends on the probability distribution of flight lengths taken by a forager that can detect target sites only in its limited vicinity. We show that, when the target sites are sparse and can be visited any number of times, an inverse square power-law distribution of flight lengths, corresponding to Lévy flight motion, is an optimal strategy. We test the theory by analysing experimental foraging data on selected insect, mammal and bird species, and find that they are consistent with the predicted inverse square power-law distributions.
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This paper concerns the autonomous tracking of fish using a Remotely Operated Vehicle (ROV) equipped with a single camera. An efficient image processing algorithm is presented that enables pose estimation of a particular species of fish - a Large Mouth Bass. The algorithm uses a series of filters including the Gabor filter for texture, projection segmentation, and geometrical shape feature extraction to find the fishes distinctive dark lines that mark the body and tail. Feature based scaling then produces the position and orientation of the fish relative to the ROV. By implementing this algorithm on each frame of a series of video frames, successive relative state estimates can be obtained which are fused across time via a Kalman Filter. Video taken from a VideoRay MicroROV operating within Paradise Lake, Ontario, Canada was used to demonstrate off-line fish state estimation. In the future, this approach will be integrated within a closed-loop controller that allows the robot to autonomously follow the fish and monitor its behavior.
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This paper describes an underwater walking robotic system being developed under the name AQUA, the goals of the AQUA project, the overall hardware and software design, the basic hardware and sensor packages that have been developed, and some initial experiments. The robot is based on the RHex hexapod robot and uses a suite of sensing technologies, primarily based on computer vision and INS, to allow it to navigate and map clear shallow-water environments. The sensor-based navigation and mapping algorithms are based on the use of both artificial floating visual and acoustic landmarks as well as on naturally occurring underwater landmarks and trinocular stereo.
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This paper presents a vision algorithm that enables automated jellyfish tracking using remotely operated vehicles (ROVs) or autonomous underwater vehicles (AUVs). The discussion focuses on algorithm design. The introduction provides a novel performance-assessment tool, called segmentation efficiency, which aids in matching potential vision algorithms to the jelly-tracking task. This general-purpose tool evaluates the inherent applicability of various algorithms to particular tracking applications. This tool is applied to the problem of tracking transparent jellyfish under uneven time-varying illumination in particle-filled scenes. The result is the selection of a fixed-gradient threshold-based vision algorithm. This approach, implemented as part of a pilot aid for the Monterey Bay Aquarium Research Institute's ROV Ventana, has demonstrated automated jelly tracking for as long as 89 min.
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We have developed a small robotic system that we hope can reduce the cost of gathering data on the movements of large fish and marine mammals. This tracking system is contained in a 10′, low-cost kayak hull and includes sub-systems that allow for its autonomous operation while following a tagged, swimming animal. The hull is polyethylene and houses lead-acid batteries for power, electric propulsion through a large, efficient propeller, a keel for stability and course-keeping, and a rudder servo for steering. An acoustic transducer is the prime mission sensor while we have installed a compass and GPS receiver for navigation. Three computers control the system, one for overall mission control, another for propulsion motor control, and another for sensor orientation. This paper describes in detail the prototype system as configured with a Vemco V60 receiver witha V11 (28-32 kHz.) hydrophone mounted on a scanning mechanism. We describe the operation of this system and discuss other sensor options and their implications on system performance. We describe the behavior algorithms implemented in the mission control software and the user interface facilitated by a removable RS-232 link to a laptop computer. Finally, we present the implications of this system on the economics of deep-ocean tracking studies.
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This chapter discusses the movement and activity pattern of California fishes. There are a number of good examples that suggest that fishes most closely associated with complex habitats tend to move less than those more loosely associated with habitat; however, there also appears to be a large amount of variability in behavior between species and individuals. Nevertheless, the general differences in movements are likely associated with energetic tradeoffs between finding food and mates, and avoiding predation or unsuitable abiotic conditions. In addition, many of the same tradeoffs have likely influenced the evolution of activity patterns seen in marine fishes. Because of the economic importance of many marine fishes in California, the need to understand fish behavior has increased, particularly for its application in resource and fisheries management.
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Dissolved oxygen (DO) concentration is a key indicator of the health and productivity of an aquatic ecosystem. This paper presents a new method for high-resolution characterization of DO as a function of both space and time. The implementation of a new oxygen optode in an Iver2 autonomous underwater vehicle (AUV) is described, which enables the system to measure both absolute oxygen concentration and percentage saturation. Also described are details of AUV missions in Hopavågen Bay, Norway, which consisted of a series of repeated undulating lawnmower patterns that covered the bay. Through offline postprocessing of data, sensor characteristic models were developed, as well as a 3D lattice time series model. The model was constructed by estimating DO at each 3D lattice node location using a 1D Kalman filter that fused local measurements obtained with the AUV. By repeating model construction for several missions that spanned 24 h, estimates of DO as a function of space and time were calculated. Results demonstrated (1) the AUVs ability to repeatedly gather high-spatial-resolution data (2) significant spatial and temporal variation in DO in the water body investigated, and (3) that a 3D model of DO provides better estimates of total DO in a volume than extrapolating from only a single 2D plane. Given the importance of oxygen within an ecosystem, this new method of estimating the quantity of DO per volume has the potential to become a reliable test for the health of an underwater ecosystem. Also, it can be refined for detecting and monitoring a range of soluble gases and dispersed particles in aquatic environments, such as dissolved O2 and CO2 around production facilities such as fish farms, or dispersed hydrocarbons and other pollutants in fragile ecosystems. © 2012 Wiley Periodicals, Inc.