Telemetry Research Articles

A Compact GPS Surface Drifter with LoRa Telemetry and Self-Contained Tracking System

AbstractShallow marine environments are characterized by complex and variable physical processes that have significance for biological and human communities. However, the global disparity in scientific resources limits examination of the coastal ocean in some regions, so the development of universal and accessible technologies is needed. We combined a compact, GPS-equipped drifter design with long-range (LoRa) radio telemetry and a receiver system housed on a research vessel to develop a low-cost, easily assembled system of drifters. LoRa transmission of real-time location data while deployed was used to increase recoverability, minimizing the initial and long-term costs of constructing and maintaining the operation of this drifter system. Bench and field testing confirmed the performance of the system, which was optimized for LoRa transmission, which is compromised when occurring near the sea surface. The swift currents, complex coastline, and varied sea states present in our study area provided a rigorous testing environment for the drifter system. We established the working limits of battery life and LoRa data transmission within our configuration of transmitters and receiver, evaluated the accuracy of the GPS receivers, and determined the most robust variant of the drifter body design. This study offers proof of concept for a radio-tracked drifter system that is ready for deployment to track nearshore surface currents. Both the drifter system and the data telemetry protocol can be adapted to other investigations of the marine environment by integrating new sensors, modifying the configuration or deployment procedure, or applying LoRa radios to transfer data from fixed sensing platforms.

Assessing the post-release effects of capture, handling and placement of satellite telemetry devices on narwhal (Monodon monoceros) movement behaviour.

Animal-borne telemetry devices have become a popular and valuable means for studying the cryptic lives of cetaceans. Evaluating the effect of capture, handling and tagging procedures remains largely unassessed across species. Here, we examine the effect of capture, handling and tagging activities on an iconic Arctic cetacean, the narwhal (Monodon monoceros), which has previously been shown to exhibit an extreme response to extended capture and handling. Using accelerometry-derived metrics of behaviour, including activity level, energy expenditure and swimming activity, we quantify the post-release responses and time to recovery of 19 individuals following capture and tagging activities considering the intrinsic covariates of sex and individual size and the extrinsic covariates of handling time and presence of a 'bolt-on' satellite telemetry device. From accelerometer-derived behaviour, most narwhals appeared to return to mean baseline behaviour (recovery) within 24hours after release, which was supported by longer-term measures of diving data. None of the covariates measured, however, had an effect on the time individuals took to recover following release. Using generalized additive models to describe changes in behaviour over time, we found handling time to be a significant predictor of activity levels, energy expenditure and swimming behaviour following release. Individuals held for the longest period (>40min) were found to display the largest effect in behaviour immediately following release with respect to swimming behaviour and activity levels. We also found some support for relationships between activity levels, energy expenditure and swimming activity and two other covariates: sex and the attachment of a bolt-on configuration satellite tags. Our results indicate that narwhals recover relatively quickly following capture, handling and tagging procedures, but we suggest that researchers should minimize handling time and further investigation is needed on how to mitigate potential effects of bolt-on satellite tags in these sensitive species.

About the revised version of AE-5201A, which is Low Power Medical Telemetry Device Usage Regulations

About the revised version of AE-5201A, which is Low Power Medical Telemetry Device Usage Regulations

Novel Microstrip Patch Antenna for implantable medical telemetry devices

ABSTRACT In recent years, close collaboration has been forged between telecommunications and medicine, which has enabled the birth of medical telemetry and therefore implanting medical devices on the human and animal body. The latter is based on implantable antennas design in the MICS (Medical Implant Communication Service) band (402-405) MHz. The frequency band is explored to design mobile and comfortable communication systems to support human life. The objective of this paper is to design and optimization of implantable printed antennas in human body for medical telemetry. The proposed antenna operates in the MICS band between 402 and 405 MHz. The antenna is simulated using HFSS software. The proposed antenna resonates at 404 MHz with a return loss of -32.58 dB, bandwidth of 26 MHz and gain of 6.5 dB.

Squirreling from Afar: Adapting Squirrel-Net Modules for Remote Teaching and Learning

The shift from face-to-face instruction to remote teaching and learning has proven to be a challenging endeavor for many reasons, including lack of time, resources, and inspiration. Lab courses, the &quot;hands-on&quot; portion of many curricula, may be especially difficult to adapt to online learning given the common use of specialized equipment, materials, and techniques that require close supervision. Without the time and resources to creatively modify existing activities or create new ones, remote lab courses run the risk of becoming less effective, equitable, and/or engaging. Squirrel-Net has created four field-based activities for biology labs that are easy to implement, highly flexible for different course aims, and readily adaptable to a remote learning environment. In this essay, we briefly summarize the modules and propose several ways that each can be adjusted to accommodate online teaching and learning. By providing authentic learning opportunities through distance delivery we hope to promote widespread student engagement and creative solutions for instructors. <em>Primary image</em>:&nbsp;A student-pair collecting behavioral data. One student observes the squirrel while the other keeps track of time and records the behavior remotely. By connecting through a video call, even students without access to squirrels may participate in the activity. Photo by Laurie Dizney. <strong>Additional Squirrel-Net articles:</strong> <ul> <li><a href="https://doi.org/10.24918/cs.2020.26">An Introduction to the Squirrel-Net Teaching Modules</a></li> <li><a href="https://doi.org/10.24918/cs.2020.7">Squirreling Around for Science: Observing Sciurid Rodents to Investigate Animal Behavior</a></li> <li><a href="https://doi.org/10.24918/cs.2020.30">Sorry to Eat and Run: A Lesson Plan for Testing Trade-off in Squirrel Behavior Using Giving Up Densities (GUDs)</a></li> <li><a href="https://doi.org/10.24918/cs.2020.25">Squirrels in Space: Using Radio Telemetry to Explore the Space Use and Movement of Sciurid Rodents</a></li> <li><a href="https://doi.org/10.24918/cs.2020.6">How Many Squirrels Are in the Shrubs? A Lesson Plan for Comparing Methods for Population Estimation</a></li> </ul>

Evaluation and Analysis of Interferograms from an InSAR Radar Encrypted by an AES-Based Cryptosystem with The Five Encryption Modes

This paper falls within the framework of the security of satellite images, in particular interferograms from an Interferometric Synthetic Aperture Radar (inSAR) system. The innovation of this work consists in the application of a cryptosystem based on two algorithms Advanced Encryption Standard (AES) and the Rivest, Shamir and Adleman (RSA) encryption algorithm for securing interferograms of inSAR systems. AES employs five encryption modes Electronic Code Book (ECB), Cipher Bloc Chaining (CBC), Cipher FeedBack (CFB), Output FeedBack (OFB), and counter-mode encryption (CTR). The use of the AES algorithm alone can only ensure the confidentiality function. In the proposed cryptosystem confidentiality is ensured by the AES algorithm, authenticity is guaranteed by the RSA algorithm, and integrity is ensured by two parameters; the correlation function between the adjacent pixels and the SSIM parameters (structural similarity index SSIM). For evaluation and analysis of security performance for interferogram encryption, several test metrics are employed. These metrics are: Analysis of histograms of the encrypted interferograms, correlation between the adjacent pixels, between the original interferogram and the encrypted interferogram, SSIM between the original interferogram and the decrypted one. Moreover, we exploit the analysis of resistance to error propagation for the five modes. The obtained results show a superiority of the OFB and CTR modes for the encryption of inSAR interferograms compared to ECB, CFB, and CBC modes. It is noteworthy, that the main criteria that can be used to choose between OFB and CTR for encryption of satellite images are propagation of errors and the complexity material for their locations on the edges of the satellites propagation of errors and the complexity material for their locations on the edges of the satellites. OFB mode is employed in satellites to minimize the number of on-board circuits, which is decisive for satellites. CTR mode is recommended by the CCSDS (Consultative Committee for Space Data Systems) for telemetry (TM) and remote control (TC) encryption.

Bayesian and frequentist approaches to multinomial count models in ecology

Multinomial count data are common in trophic ecology, spatial ecology, and community ecology. Compared to generalized linear models (GLMs) for univariate data, fewer statistical programs have been developed for the multivariate counterpart of GLMs. Studies of spatiotemporal community dynamics and spatial ecology on large spatial scales may generate large or big data on compositional counts or proportions. Fast, reliable computational methods can promote applications of multivariate generalized linear models (MGLMs) in predictive ecology and ecological informatics. The main objective of this study was to build Dirichlet-multinomial (D-M) models for compositional counts using frequentist's maximum likelihood estimation (MLE) with template model builder (TMB), full Bayesian estimation with programs JAGS and Stan, and variational Bayes in Stan. Bayesian and frequentist D-M models were applied to the compositional counts of radio telemetry locations of ring-necked pheasants (Phasianus colchicus) and American beaver (Castor canadensis) in different habitat-cover types to estimate habitat selection index. Bayesian D-M models with JAGS and Stan produced similar estimates as TMB programs. However, TMB programs ran a few hundred times faster than the Bayesian models. Template model builder and Stan are flexible in building complex statistical models and can accommodate a large number of parameters and random effects. The joint use of TMB and Stan may help develop MGLMs and multivariate generalized linear mixed models for large ecological data.

Assessing the effect of tagging and the vulnerability to predation in tigerfish (Hydrocynus vittatus, Castelnau 1861) in a water-stressed system using telemetry methods

Increase in anthropogenic pressures on freshwater ecosystems, globally and locally in South Africa, has made it difficult to meet environmental flow requirements and maintain these systems. The Letaba-Olifants catchment is one such example, where the upstream water demands place pressure on the river downstream as it flows through the Kruger National Park. We used the activity rates of Hydrocynus vittatus as a line of evidence to assess (1) the effects of telemeter tagging on their activity rates in three potential post-tagging recovery periods and (2) their vulnerability to predation and the causality related to the environmental stressors placed on the river catchment in the Olifants River Gorge, Kruger National Park, South Africa. We determined H. vittatus activity rates as locomotive movement using radio telemetry methods linked remotely to an online data management system. We telemeter tagged nine individuals from 08 May to 28 June 2018. However, only seven fish were successfully tracked for the duration of our study, and two individuals moved out of range of the remote network shortly after release and could not be located. The tagged H. vittatus individuals were found to have reduced activity at least within the first 7 days after tagging compared with the time after that. The results showed that three individuals were preyed on by predators after the tagging procedure recovery period. This coincided with abnormal low flow conditions, where the Letaba River ran dry. African fish eagles Haliaeestus vocifer were the only confirmed predator, whilst predation by other species was also evident.Conservation implications: Monitoring of H. vittatus using telemetry is a viable tool to use when assessing environmental stressors in remote locations. The abnormally low water levels in the Olifants and Letaba Rivers (cessation of flow in the Letaba River) during our study may have compromised the predator avoidance strategies of tagged H. vittatus and may further be affecting the viability of the H. vittatus populations in Kruger National Park. The synergistic effects of natural and anthropogenic stressors impact negatively H. vittatus populations and potentially other aquatic biotas.

Locating large insects using automated VHF radio telemetry with a multi‐antennae array

Abstract We describe an automated radio telemetry system (ARTS) designed for estimating the location of 0.50 g butterflies which was constructed with commercially available materials. Previously described systems were not designed to estimate fine‐scale locations of large insects within approximately 200 m2 study areas. The ARTS consists of four receiving stations. Each receiving station has four 3‐element, directional Yagi antennae (separated by 60) connected to an automated receiver that records detected power sequentially from each antenna. To develop and evaluate the ARTS performance, four receiving stations were installed in the corners of 4 and 6.25‐ha square fields with varying heights of vegetative cover. The location of a 0.22 g transmitter was estimated with a statistical method implementing both distance‐and angle‐power relationships. Calibrated model parameters were based on power detected from transmitters at known locations. Using independently collected data, model performance was evaluated based on estimated locations of a georeferenced stationary transmitter, a moving transmitter with a known georeferenced path and a transmitter attached to a monarch butterfly Danaus plexippus. Estimated locations were calculated as frequently as every 5 s, which is at least 12 times greater than the sampling frequency previously reported for tracking insects. When sufficient power data were received, the median estimated locations of a transmitter attached to an investigator's hat were &lt;16 m from the true location. The median effective radius of the 95% confidence ellipse was 18.3 m for stationary targets and 15.9 m for a moving transmitter. Greater error in location estimation was expected when the transmitter was attached to a monarch butterfly due to interference from vegetation and variability in antenna orientation and transmitter height. As such, the median distance between the estimated and true locations was 72 m. After applying a correction for the effect of vegetation, median location error was reduced by 12 m. While our ARTS has likely reached the limit of current technology, the system is still a substantial methodological advancement for locating butterflies. Our efforts should provide a benchmark as technology improves.

Monitoring Network Changes during the 2018 Kīlauea Volcano Eruption

Abstract In the summer of 2018, Kīlauea Volcano underwent one of its most significant eruptions in the past few hundred years. The volcano’s summit and East Rift Zone magma system partially drained, resulting in a series of occasionally explosive partial caldera collapses, and widespread lava flows in the lower East Rift Zone. The Hawaiian Volcano Observatory (HVO) operates a robust permanent monitoring network of about 250 stations, recording a variety of real-time data streams: seismic (short-period, broadband, strong-motion), infrasound, Global Navigation Satellite Systems (GNSS), tilt, camera, laser rangefinder, and gas geochemistry. During the eruption, HVO staff quickly established 35 new temporary monitoring stations, to better constrain evolving volcanic hazards. The partial collapses of the caldera threatened to disrupt important telemetry links in the HVO monitoring network, and a major effort was undertaken in the midst of the eruption crisis to reroute radio telemetry and maintain continuity of data flow. In the process, a new data center was established in Hilo, to mitigate a long-standing potential single point of failure at the HVO facility. Over the course of the eruption from May through August, lava, ashfall, wildfire, and cliff collapse destroyed or disabled 36 stations. Thousands of earthquakes damaged the main HVO facility at Uēkahuna Bluff, causing staff to evacuate the building and relocate observatory operations in the midst of the eruption response, adding more complexity to the response effort. Throughout these events, the HVO team maintained the monitoring network, provided timely information to the public and emergency managers, and collected valuable scientific data to better understand Kīlauea Volcano.

Implications of vestibular telemetry for the management of Ménière’s Disease—Our experience with three adults

Implications of vestibular telemetry for the management of Ménière’s Disease—Our experience with three adults

Wireless, miniaturized, semi-implantable electrocorticography microsystem validated in vivo

This paper reports on the design, development, and test of a multi-channel wireless micro-electrocorticography (µECoG) system. The system consists of a semi-implantable, ultra-compact recording unit and an external unit, interfaced through a 2.4 GHz radio frequency data telemetry link with 2 Mbps (partially used) data transfer rate. Encased in a 3D-printed 2.9 cm × 2.9 cm × 2.5 cm cubic package, the semi-implantable recording unit consists of a microelectrode array, a vertically-stacked PCB platform containing off-the-shelf components, and commercially-available small-size 3.7-V, 50 mAh lithium-ion batteries. Two versions of microelectrode array were developed for the recording unit: a rigid 4 × 2 microelectrode array, and a flexible 12 × 6 microelectrode array, 36 of which routed to bonding pads for actual recording. The external unit comprises a transceiver board, a data acquisition board, and a host computer, on which reconstruction of the received signals is performed. After development, assembly, and integration, the system was tested and validated in vivo on anesthetized rats. The system successfully recorded both spontaneous and evoked activities from the brain of the subject.

Методи трекінгу земноводних

ntroduction: In this article, we present a literature review of modern, most common, and useful methods of amphibian tracking. Amphibians are the most sensitive group of animals and near 41 % of species are under the risk of extinction. Therefore, the research of spatial movements of amphibians is one of the most topical tasks of modern herpeto­logy. The information about the use of space is needed for practical protection of sensitive species of amphibians, for planning of protected areas, estimation of the potential danger for some groups of animals when designing infrastructure objects, such as roads. The movement studies gained popularity and have been undertaken since the second part of the 20th century. Such growth in the number of studies is related to the recent advances in radio-electronic technology that contributed to the creation of a range of instruments for automatic or semi-automatic tracking of individual animals. Unfortunately, most of such methods are still too expensive for scientists from developing countries. Thus, classical methods are still widely used. Results: We describe six methods of amphibians tracking: radioisotope tracking, automated radio telemetry, harmonic direction finding, radio frequency identification, fluorescent powder, spool tracking. Each of these methods allows collecting detailed information about spatial movements of individuals. Many of these tracking methods require using of a special tag, which is attached to an animal and used for its further detection. Different types of tags have identical functions but are based on different principles of use. Two of the described methods do not require using of tags and are cheap. These are fluorescent powder and spool tracking. In the article, we provide many links to grant programs and places where special equipment can be found. Conclusions: As a result of literature review, we created a table with concise information about all the described methods. Using this table one can choose the best method for an experiment. Keywords: amphibians, radiotelemetry, fluorescent powder, radioisotope tracking, spool tracking

Intrauterine Exposure to Diabetic Milieu Does Not Induce Diabetes and Obesity in Male Adulthood in a Novel Rat Model.

Several studies show an association of maternal diabetes during pregnancy with adverse offspring metabolic health. Other studies, however, suggest that this effect might be biased by obesity, which is independently associated with offspring metabolic disease and often coexistent to maternal diabetes. We performed a prospective study in a rat model to test the hypothesis that the burden of a diabetic pregnancy without obesity deteriorates metabolic health in male offspring. We generated maternal type 2 diabetes before conception that persisted during pregnancy by knockdown of the insulin receptor in small hairpin RNA-expressing transgenic rats. Male WT (wild type) offspring were followed up until adulthood and metabolically challenged by high-fat diet. Blood glucose was measured continuously via a telemetry device. Glucose and insulin tolerance tests were performed, and body composition was analyzed. Weight gain and glucose levels during adolescence and adulthood were similar in male offspring of diabetic and control pregnancies. Body weight and fat mass after high-fat diet, as well as glucose and insulin tolerance tests, were unaltered between male adult offspring of both groups. Glycemic control consisting of up to 49 000 individual glucose measures was comparable between both groups. Intrauterine exposure to maternal hyperglycemia and hyperinsulinemia without obesity had no impact on male offspring metabolic health in our model. We conclude that the intrauterine exposure itself does not represent a mechanism for fetal programming of diabetes and obesity in our model. Other maternal metabolic parameters during pregnancy, such as obesity, might impact long-term offspring metabolic health.

Weather-influenced water-crossing behaviour of black kites (Milvus migrans) during migration

From 2014 to 2020, 32 black kites from various European countries were tagged with telemetry devices and tracked to study their spatiotemporal behaviour. Eleven birds which crossed the Mediterranean Sea and the Black Sea directly over large water bodies out of traditional migration routes over the Strait of Gibraltar, the Dardanelles/the Bosporus area and the east coast of the Black Sea were selected for this study. Ten birds attempted to cross the Mediterranean Sea and one attempted to cross the Black Sea. All black kites crossed the sea successfully but in one case the bird failed. The maximum water crossing length was recorded at 542 km. The average speed of the birds crossing the sea included a broad range from 27.7 to 97 kph. There was a correlation between average speed and tail-wind speed during the crossing. We conclude that the most favourable conditions for black kites when crossing large water bodies such as the Mediterranean and Black seas were sunny to partly cloudy weather with temperatures over 20 °C, the speed of the tailwind of 1.1–10.8 m/s and the air pressure over the standard value of 1013 hPa.

Performance enhancement of DFBL based near‐infrared CH4 telemetry system using a focus tunable lens

AbstractA methane telemetry system for 1653 nm DFB laser based on TDLAS‐WMS technology is developed in this article. The focus tunable lens is used as the collimating system of the telemetry device to solve the problem that the telemetry device cannot be dynamically adjusted under different detection environments. Experimental results show that the root mean square error was 7.6205 and the theoretical limit of detection (LoD) was 1.473 parts per million (ppm) while the optimal integration time reaches 30 s. The near‐infrared CH4 telemetry system is suitable for different detection environments of natural gas leakage and has good detection performance and stable and reliable operation.

ESTIVATION SITE SELECTION OF WESTERN CHICKEN TURTLES (DEIROCHELYS RETICULARIA MIARIA)

Western chicken turtles (Deirochelys reticularia miaria) spend most of the year estivating on land, but researchers know little about their choice of estivation locations, and understanding their terrestrial requirements is important for conservation efforts. Therefore, we used radio telemetry to examine the estivation locations of nine males and four females. We followed six of those males and three of those females for 2 years, and two males and one female for 3 years. We examined site fidelity and compared the habitat features of their estivation locations to the habitat available in the area. We found that males exhibited site fidelity across years, but females generally did not. We also found that D. r. miaria selected sites that contained small-mammal burrows, leaf litter, and <25% vegetative ground cover. There was no evidence of selection for sites with or without slopes. Because this species relies on estivation sites with specific characteristics, protecting suitable habitat is an important part of conservation efforts. This study can help to guide those efforts.

Abstract 15203: Acute Electronic Cigarette Exposure Decreases Heart Rate Variability in C57BL/6 Mice

Background: Despite a lack of empirical data, an unprecedented rise in electronic cigarettes (ECs) has been widely perceived as safe. Multiple studies support a causal link between tobacco cigarette (TC) use and a decline in cardiovascular (CV) health; however, there is a paucity of data with EC use. A study showed EC use decreased HRV in humans via increased sympathetic activation- a known mechanism predictive of CV disease from TC use. We aimed to develop a mouse model to determine if acute EC exposure modifies HRV in mice. Methods: Telemetry devices were implanted in the abdomen of 6 eight-week-old C57BL/6 mice to monitor ECG activity continuously. Mice underwent a 1-hr acclimation phase in exposure chambers followed by a 1-hour exposure to air (control). EC exposures consisted of two 15-min sessions (4-sec puff/26-sec air) to BluPlus® 2.4% nicotine (Classic Tobacco) with a 15-min period of aerosolized PBS added as a secondary control. For each exposure episode, a 45-min post-exposure event followed. Ponemah v6.20 software was used for HRV analysis of the time domain. A linear mixed-effects model with a robust estimator was used to determine the relationship between air vs. combined EC events and PBS (n = 1,109). R (Version R3.6.3) was utilized to test for statistical significance at α = 0.05. Results: EC exposures significantly decreased the standard deviation of NN intervals (SDNN) and root mean square of successive differences (RMSSD) by 5.00 and 9.34 units as compared to air exposures, suggesting reductions in total and short-term autonomic variability (Table 1). Both parameters increased in the post-EC periods as compared with the EC exposures. Conversely, PBS vs. air exposure showed a marked increase in SDNN and RMSSD. Conclusion: Short-term exposures to ECs decreased HRV in mice, consistent with similar results in human studies, suggesting that ECs could increase cardiovascular risk in an acute manner.

USE OF FLUMETHRIN-IMPREGNATED COLLARS TO MANAGE AN EPIDEMIC OF SARCOPTIC MANGE IN AN URBAN POPULATION OF ENDANGERED SAN JOAQUIN KIT FOXES (VULPES MACROTIS MUTICA )

Sarcoptic mange epidemics can have long-lasting impacts on susceptible wildlife populations, potentially contributing to local population declines and extirpation. Since 2013, there have been 460 reported cases of sarcoptic mange in an urban population of endangered San Joaquin kit foxes (Vulpes macrotis mutica) in Bakersfield, CA, with many of them resulting in fatality. As part of a multifaceted response to mitigate mange-caused mortalities and reduce this conservation threat, a 2-yr randomized field trial was conducted to assess the efficacy of long-acting flumethrin collars against sarcoptic mange in kit foxes. Thirty-five kit foxes living in a high-density population on a college campus were captured, examined, administered selamectin, and each fox randomly assigned to either receive a flumethrin collar placed within a VHF radio collar or a VHF radio collar without flumethrin. The survival and mange-infestation status of study animals was monitored via radio telemetry, remote cameras, and periodic recapture examinations and compared among treated and control kit foxes using a Cox proportional hazards model. The average time to onset of mange for treated kit foxes (176 days) was similar to controls (171 days) and treatment with flumethrin did not significantly reduce mange risk for all kit foxes. Kit foxes that had a mild mange infestation at the beginning of the study were four times more likely to develop mange again, regardless of flumethrin treatment, compared with kit foxes that had no signs at initial recruitment. This study demonstrates an approach to evaluating population-level protection and contributes to the limited literature on efficacy, safety, and practicality of acaricides in free-ranging wildlife.

The spawning location of vulnerable ferox trout (Salmo trutta L.) in the Lough Corrib and Lough Mask catchments, Western Ireland.

Ferox trout are large, long-lived, piscivorous trout normally found in deep lakes; they are highly prized by trophy anglers. Lough Corrib and Lough Mask, Western Ireland, have recorded the majority of Irish specimen ferox trout since angling records began. Little was known regarding the spawning location of ferox trout relative to sympatric brown trout, and a radio telemetry study was initiated in both catchments in 2005. Over the period 2005-2009, 79 ferox were captured by angling and radio tagged in Lough Corrib, while 55 ferox were tagged in Lough Mask. Manual and helicopter tracking were carried out on all spawning streams entering both lakes over the autumn/winter period to detect tagged fish. Overall, 37 radio-tagged trout (46.8%) were detected in Lough Corrib streams and 21 tagged trout (38.2%) were recorded from Lough Mask streams. Results from radio tracking indicate that the majority (92%) of ferox trout tagged in Lough Corrib spawned in a single spawning stream, the Cong river, while the majority (76%) of ferox trout tagged in Lough Mask spawned in the Cong canal and Cong river. These results suggest that these streams are most likely the principle spawning locations of ferox trout in both lakes. The occurrence of ferox trout predominantly in single spawning rivers in both catchments highlights the vulnerability of the study ferox populations. As a result of these findings, conservation measures were introduced for ferox trout in both catchments.