Daily Position Research Articles

GPS measurements on pre-, co- and post-seismic surface deformation at first multi-parametric geophysical observatory, Ghuttu in Garhwal Himalaya, India

Abstract We investigate the surface deformation pattern of GPS station at MPGO Ghuttu (GHUT) to find out the cause of anomalous behavior in the continuous GPS time series. Seven years (2007-2013) of GPS data has been analyzed using GAMIT/GLOBK software and generated the daily position time series. The horizontal translational motion at GHUT is 43.7 ± 1 mm/yr at an angle of 41°± 3° towards NE, while for the IGS station at LHAZ, the motion is 49.4 ±1 mm/yr at 18 ± 2.5° towards NEE. The estimated velocity at GHUT station with respect to IISC is 12 ± 1 mm/yr towards SW. Besides, we have also examined anomalous changes in the time series of GHUT before, after and during the occurrences of local earthquakes by considering the empirical strain radius; such that, a possible relationship between the strain radius and the occurrences of earthquakes have been explored. We considered seven local earthquakes on the basis of Dobrovolsky strain radius condition having magnitude from 4.5 to 5.7, which occurred from 2007 to 2011. Results show irrespective of the station strain radius, pre-seismic surface deformational anomalies are observed roughly 70 to 80 days before the occurrence of a Moderate or higher magnitude events. This has been observed for the cases of those events originated from the Uttarakashi and the Chamoli seismic zones in the Garhwal and Kumaun Himalaya. Occurrences of short (< 100 days) and long (two years) inter-seismic events in the Garhwal region plausibly regulating and diffusing the regional strain accumulation.

Daily localization of partial breast irradiation patients with three-dimensional ultrasound imaging.

PurposeAccurate localization of the lumpectomy cavity during accelerated partial breast radiation (APBR) is essential for daily setup to ensure the prescribed dose encompasses the target and avoids unnecessary irradiation to surrounding normal tissues. Three-dimensional ultrasound (3D-US) allows direct visualization of the lumpectomy cavity without additional radiation exposure. The purpose of this study was to evaluate the feasibility of 3D-US in daily target localization for APBR.Materials and methods: Forty-seven patients with stage I breast cancer who underwent breast conserving surgery were treated with a 2-week course of APBR. Patients with visible lumpectomy cavities on high quality 3D-US images were included in this analysis. Prior to each treatment, X-ray and 3D-US images were acquired and compared to images from simulation to confirm accurate position and determine shifts. Volume change of the lumpectomy cavity was determined daily with 3D-US.ResultsA total of 118 images of each modality from 12 eligible patients were analyzed. The average change in cavity volume was 7.8% (range, -24.1% to 14.4%) on 3D-US from simulation to the end-of-treatment. Based on 3D-US, significantly larger shifts were necessary compared to portal films in all three dimensions: anterior/posterior (p = 7E-11), left/right (p = 0.002), and superior/inferior (p = 0.004).ConclusionGiven that the lumpectomy cavity is not directly visible via X-ray images, accurate positioning may not be fully achieved by X-ray images. Therefore, when the lumpectomy cavity is visible on US, 3D-US can be considered as an alternative to X-ray imaging during daily positioning for selected patients treated with APBR, thus avoiding additional exposure to ionizing radiation.

The effect of the choice of patient model on the performance of in vivo 3D EPID dosimetry to detect variations in patient position and anatomy.

In vivo EPID dosimetry is meant to trigger on relevant differences between delivered and planned dose distributions and should therefore be sensitive to changes in patient position and patient anatomy. Three-dimensional (3D) EPID back-projection algorithms can use either the planning computed tomography (CT) or the daily patient anatomy as patient model for dose reconstruction. The purpose of this study is to quantify the effect of the choice of patient model on the performance of in vivo 3D EPID dosimetry to detect patient-related variations. Variations in patient position and patient anatomy were simulated by transforming the reference planning CT images (pCT) into synthetic daily CT images (dCT) representing a variation of a given magnitude in patient position or in patient anatomy. For each variation, synthetic in vivo EPID data were also generated to simulate the reconstruction of in vivo EPID dose distributions. Both the planning CT images and the synthetic daily CT images could be used as patient model in the reconstructions yielding and EPID reconstructed dose distributions respectively. The accuracy of and reconstructions was evaluated against absolute dose measurements made in different phantom setups, and against dose distributions calculated by the treatment planning system (TPS). The comparison was performedby γ-analysis (3% local dose/2mm). The difference in sensitivity between and reconstructions to detect variations in patient position and in patient anatomy was investigated using receiver operating characteristic analysis and the number of triggered alerts for 100 volumetric modulated arc therapy plans and 12 variations. showed good agreement with both absolute point dose measurements (<0.5%) and TPS data (γ-mean=0.52±0.11). The agreement degraded with , with the magnitude of the deviation varying with each specific case. readily detected combined 3mm translation setup errors in all directions (AUC=1.0) and combined 3° rotation setup errors around all axes (AUC=0.86) whereas showed good detectability only for 12mm translations (AUC=0.85) and 9° rotations (AUC=0.80). Conversely, manifested a higher sensitivity to patient anatomical changes resulting in AUC values of 0.92/0.95 for a 6mm patient contour expansion/contraction compared to 0.70/0.64 with . Using |ΔPTVD50 |>3% as clinical tolerance level, the percentage of alerts for 6mm changes in patient contour were 85%/27% with . With planning CT images as patient model, EPID dose reconstructions underestimate the dosimetric effects caused by errors in patient positioning and overestimate the dosimetric effects caused by changes in patient anatomy. The use of the daily patient position and anatomy as patient model for in vivo 3D EPID transit dosimetry improves the ability of the system to detect uncorrected errors in patient position and it reduces the likelihood of false positives due to patient anatomical changes.

Accuracy and Precision of an Ultrasound-Based Device to Measure the Pelvic Tilt in Several Positions.

A new ultrasound-based device is proposed to measure the patient-specific pelvic tilt in different daily positions. The aim of this study was to assess the accuracy of this device as well as the intraobserver and interobserver precisions. The accuracy was assessed by performing several tilt measurements with the device on a testing mechanical bench. The error was defined as the difference between the tilt measured with the device and the tilt provided by this test bench. Three physicians, a novice, an intermediate, and an expert user, were also asked to perform 10 measurements on 3 healthy volunteers with low, medium, and high body mass indices to analyze the intraobserver and interobserver precisions. These 10 measurements were performed in the standing, sitting, and supine positions. The mean accuracy of the device ± SD was 1.1° ± 0.7° (range, 0°-4.0°). The interobserver and intraobserver precisions were excellent whatever the body mass index and good to excellent according to the positions. There was no learning curve, and the time required to complete the measurements was approximately 5 minutes. This study presents an accurate and precise noninvasive device for measurement of the pelvic tilt in different positions.

Statistical Analysis of Students’ Behavioral and Attendance Habits in Engineering Education

This study aims at quantifying the relationship between the marks of students and their seating position in the classroom. The study is cross-sectional, quantitative, observational, and correlational. It analyzed data collected throughout two academic years about the students’ marks (in different terms, courses, and degrees) and about their daily seating position (so, every change was recorded) for both theory and practice lessons. The quantitative data collected in the study was statistically analyzed. The main result is that the seating position is significantly correlated with the marks in the studied context (engineering schools with classrooms with 5-66 students). Other side results show a positive influence on marks of working alone with respect to sharing the computer with a classmate; indicate where do students who give up the course usually sit, and when in the academic term do, they give up. This article provides empirical data with regards to the relation between classroom seating and academic performance in engineering schools. The results obtained quantify this relation, but they cannot determine whether it is causal, consequential, or both. This study complements other studies that correlated motivation with seating preferences.

ESTRO ACROP consensus guideline on the use of image guided radiation therapy for localized prostate cancer

Use of image-guided radiation therapy (IGRT) helps to account for daily prostate position changes during radiation therapy for prostate cancer. However, guidelines for the use of IGRT are scarce.An ESTRO panel consisting of leading radiation oncologists and medical physicists was assembled to review the literature and formulate a consensus guideline of methods and procedure for IGRT in prostate cases. Advanced methods and procedures are also described which the committee judged relevant to further improve clinical practice. Moreover, ranges for margins for the three most popular IGRT scenarios have been suggested as examples.

A modified phase clock/bias model to improve PPP ambiguity resolution at Wuhan University

Precise point positioning ambiguity resolution (PPP-AR) is a valuable tool for high-precision geodetic observations, while phase bias products are critical to implementing GNSS PPP-AR. Based on the conventional integer clock and uncalibrated phase delay (UPD) models, we proposed a modified phase clock/bias model to enable undifferenced ambiguity fixing where it is the phase clocks, rather than the International GNSS Service (IGS) legacy clocks, which are estimated in a network solution by first correcting carrier-phase data for both pre-resolved integer ambiguities and predetermined phase biases. Such phase clock/bias product is compatible with IGS legacy clock and code bias products as opposed to the integer clock model, while ensuring more accurate daily positions in contrast to the UPD model. We carried out precise point positioning (PPP) ambiguity fixing using 1 year of GPS data from about 500 stations and took the IGS weekly solutions as benchmarks: The phase clock/bias model reproduced the positioning achievement of the integer clock model without biasing pseudorange processing, whereas improving markedly the east component of daily positions by 20% compared to the UPD model; interestingly, negligible differences exist between the UPD-based hourly positions and those based on the phase clock/bias model, corroborating that the UPD model is a good approximation to the phase clock/bias model in case of short observation periods. Finally, since phase biases are linearly dependent on clocks, we suggest to compute daily phase bias products, instead of the usual 15-min UPDs, by driving all their temporal variations to the phase clocks, which will greatly facilitate ambiguity-fixed PPP (ftp://igs.gnsswhu.cn/pub/whu/phasebias).

Mística, yerbas santas y solidaridad: memoria del cuidado no médico de la lepra en Agua de Dios

Introducción: la representación social de la lepra como una enfermedad del pasado, el carácter local que la circunscribe a los sanatorios y el escaso contacto de trabajadores de la salud foráneos con la enfermedad hace pensar que el conocimiento sobre su cuidado ha circulado entre generaciones de una manera más o menos confinada. Ese saber que incorpora no solo conocimiento biomédico, sino expresiones en saberes, creencias, prácticas, relatos, los actores que las construyen y recrean y su relación compleja con las dinámicas de inserción en el territorio, se constituye hoy, en sí mismo, en un patrimonio vivo, que merece ser narrado. Desarrollo: se parte de comprender la memoria de los cuidados no médicos de la lepra en Agua de Dios, por medio de un estudio etnográfico, cuyos resultados permiten proponer dos expresiones. La primera involucra a agentes de salud no médicos y su relación con los sujetos de cuidado; que muestra que el cuidado demanda no solo conocimiento científico, sino también disposiciones particulares de los sujetos, como capacidad de escucha, observación, paciencia y trascendencia, acompañadas de un posicionamiento y negociación cotidianos en el territorio. La segunda está compuesta por las alternativas de cuidado intermediadas por otros agentes con saberes autorizados, que agrupan una amplia farmacopea relacionada con el uso de plantas medicinales, referencias a curanderos y prácticas solidarias de tutoría entre pacientes y relaciones de su bienestar con el medio ambiente. Conclusiones: todas estas expresiones de cuidado desafían los discursos y prácticas canónicas de la biomedicina alrededor de esta enfermedad.

Imaging rapid early afterslip of the 2016 Pedernales earthquake, Ecuador

High-Rate (HR) GPS time series following the 2016 Mw 7.8 Pedernales earthquake suggest significant postseismic deformation occurring in the early postseismic period (i.e. first few hours after the earthquake) that is not resolved with daily GPS time series. To understand the characteristics of early postseismic deformation, and its relationship with the mainshock rupture area, aftershocks and longer-term postseismic deformation, we estimate the spatio-temporal distribution of early afterslip with HR-GPS time series that span ∼2.5 min to 72 hr after the earthquake, and compare with afterslip models estimated with daily GPS time series spanning a similar postseismic time period and up to 30 days after the earthquake. Inversion of the HR-GPS time series enables us to image the initiation of afterslip in the initial hours after the earthquake, bringing us closer to the transition between the coseismic and postseismic phases. The spatial signature of early afterslip in the region updip of the mainshock rupture area is consistent with longer-term afterslip that occurs in the 30-day postseismic period, indicating that afterslip initiated updip of and adjacent to peak coseismic slip asperities, in two localised areas, and subsequently continued to grow in amplitude with time in these specific areas. A striking difference, however, is that inversion of the 72-hour HR-GPS time series suggests early afterslip within the mainshock rupture area, but which may have been short-lived. Finally, using the first daily GPS position as the origin of the postseismic displacement (here at 12 hr after the earthquake) biases the postseismic geodetic moment, with ∼60% missing over the first 72 hr, that corresponds to ∼10% over the first 30 days. The results of our study demonstrate that imaging the spatio-temporal evolution of afterslip using subdaily GPS time series is important for evaluating postseismic slip budgets, and provides additional insights into the postseismic slip behaviour of faults.

Performance of Galileo-only dual-frequency absolute positioning using the fully serviceable Galileo constellation

The recent development of the Galileo space segment and the accompanying support of the International GNSS Service (IGS) allows for worldwide Galileo-only positioning. In this study, different techniques of dual-frequency absolute positioning using the fully serviceable Galileo constellation are evaluated for the first time and compared to the performance of GPS positioning. The daily static positioning based on the broadcast ephemeris using Galileo pseudoranges is significantly more accurate than the corresponding GPS solutions, obtaining the accuracy of a few decimeters. In the kinematic mode, the accuracy is better than 10 m and 20 m for the horizontal and vertical components, respectively, which is comparable to that of GPS. Precise absolute positioning using pseudorange and carrier phase Galileo observations combined with IGS Real-Time Service (RTS) or Multi-GNSS Experiment products is not yet as good as the corresponding GPS solutions. In the static mode, the root mean squared error (RMSE) between estimated and reference coordinates does not exceed 0.05 m and 0.06 m for the horizontal and vertical components, respectively. In the kinematic mode, the respective accuracies are better than 0.17 m and 0.21 m. Moreover, we show that both GPS and Galileo pseudorange solutions benefit from the RTS when compared to the broadcast solutions with the improvement in the accuracy between 10 and 59%. Remarkable results are achieved for Galileo Precise Point Positioning (PPP) solutions based on the broadcast ephemeris. In the static mode, the RMSE is 0.07 and 0.10 m for the horizontal and vertical components which is three and two times better, respectively, then the corresponding solutions based on GPS.

Time‐Dependent Behavior of a Near‐Trench Slow‐Slip Event at the Hikurangi Subduction Zone

AbstractStudying offshore slow‐slip events (SSEs) along subduction zone interfaces is important for constraining the overall slip budget and potential for seismic slip and the relationship with large megathrust earthquakes. Models using only onshore data increasingly lack model resolution the further from the shore the SSE occurs. In this study, we combine data from the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip seafloor absolute pressure gauge (APG) network with daily position time series from New Zealand's GeoNet to create time‐dependent models of slip during the 2014 Gisborne, New Zealand SSE using the Network Inversion Filter. We compare models assuming heterogeneous versus homogenous elastic properties to explore their influence on our models. The time‐dependent results show that slip uncertainties under the APGs drop by about 23%. We also find that the peak value of slip increases with heterogeneous elastic properties as compared to homogenous models. The inclusion of the offshore APG data in our models places more slip near the trench and detects a more defined migration of slip, especially in the heterogeneous model. These differences are important for interpreting the relationship between the SSE and associated tremor, which occurs after the peak SSE slip rate. Additionally, we use a static “potency bounding” technique in order to gauge the range of models that can fit the data. This analysis demonstrates that the inclusion of offshore data helps to substantially narrow the range of plausible slip models.

Depth Migration of Seismovolcanic Tremor Sources Below the Klyuchevskoy Volcanic Group (Kamchatka) Determined From a Network‐Based Analysis

AbstractWe present a method for automatic location of dominant sources of seismovolcanic tremor in 3‐D, based on the spatial coherence of the continuously recorded wavefield at a seismic network. We analyze 4.5 years of records from the seismic network at the Klyuchevskoy volcanic group in Kamchatka, Russia, when four volcanoes experienced tremor episodes. After enhancing the tremor signal with spectral whitening, we compute the daily cross‐correlation functions related to the dominant tremor sources from the first eigenvector of the spectral covariance matrix and infer their daily positions in 3‐D. We apply our technique to the tremors beneath Shiveluch, Klyuchevskoy, Tolbachik, and Kizimen volcanoes and observe the yearlong preeruptive volcanic tremor beneath Klyuchevskoy from deep to shallow parts of the plumbing system. This observation of deep volcanic tremor sources demonstrates that the cross‐correlation‐based method is a very powerful tool for volcano monitoring.

Migratory corridor linking Atlantic green turtle, Chelonia mydas, nesting site on Bioko Island, Equatorial Guinea to Ghanaian foraging grounds.

This study uses satellite telemetry to track post-nesting movements of endangered green turtles (Chelonia mydas) (n = 6) in the Gulf of Guinea. It identifies a migratory corridor linking breeding grounds of Atlantic green turtles nesting on Bioko Island, Equatorial Guinea, to foraging grounds in the coastal waters of Accra, Ghana. Track lengths of 20–198 days were analyzed, for a total of 536 movement days for the six turtles. Migratory pathways and foraging grounds were identified by applying a switching state space model to locational data, which provides daily position estimates to identify shifts between migrating and foraging behavior. Turtles exhibited a combination of coastal and oceanic migrations pathways that ranged from 957 km to 1,131 km. Of the six turtles, five completed their migration and maintained residency at the same foraging ground near the coastal waters of Accra, Ghana until transmission was lost. These five resident turtles inhabit heavily fished waters and are vulnerable to a variety of anthropogenic threats. The identification of these foraging grounds highlights the importance of these coastal waters for the protection of the endangered Atlantic green turtle.

Reconstruction of long-distance bird migration routes using advanced machine learning techniques on geolocator data.

Geolocators are a well-established technology to reconstruct migration routes of animals that are too small to carry satellite tags (e.g. passerine birds). These devices record environmental light-level data that enable the reconstruction of daily positions from the time of twilight. However, all current methods for analysing geolocator data require manual pre-processing of raw records to eliminate twilight events showing unnatural variation in light levels, a step that is time-consuming and must be accomplished by a trained expert. Here, we propose and implement advanced machine learning techniques to automate this procedure and we apply them to 108 migration tracks of barn swallows ( Hirundo rustica). We show that routes reconstructed from the automated pre-processing are comparable to those obtained from manual selection accomplished by a human expert. This raises the possibility of fully automating light-level geolocator data analysis and possibly analysing the large amount of data already collected on several species.

Assessing the Impact of the Basel III Leverage Ratio on the Competitive Landscape of US Derivatives Markets: Evidence from Options

This paper examines the impact of Basel III leverage ratio on the competitive landscape of US derivatives markets. Because the leverage ratio focuses on notional amounts and does not fully recognize offsetting positions and risk-mitigating collateral, it is more likely the binding constraint for derivatives. The leverage ratio also put heterogeneous constraints on different types of institutions and activities. Using daily positions of clearing members and their customers on SP (2) US banks lose market share to European banks; (3) banks' clearing activities shift away from customer accounts to house accounts; (4) low-delta options are affected most by the leverage ratio. All hypotheses are confirmed in the data. Short-dated US Treasury futures options, which receive zero exposure in the leverage ratio calculation, do not exhibit such behavior. Our evidence suggests that the leverage ratio requirement pushes derivatives activities toward less constrained institutions and market segments.

First clinical retrospective investigation of limited projection CBCT for lung tumor localization in patients receiving SBRT treatment

To clinically investigate the limited-projection CBCT (LP-CBCT) technology for daily positioning of patients receiving breath-hold lung SBRT radiation treatment and to investigate the feasibility of reconstructing fast 4D-CBCT from 1 min 3D-CBCT scan.Eleven patients who underwent breath-hold lung SBRT radiation treatment were scanned daily with on-board full-projection CBCT (CBCT) using half-fan scan. A subset of the CBCT projections and the prior planning CT were used to estimate the LP-CBCT images using the weighted free-form deformation method. The limited projections are clusteringly sampled within fifteen sub-angles in 360° in order to simulate the fast 1 min scan for 4D-CBCT. The estimated LP-CBCTs were rigidly registered to the planning CT to determine the clinical shifts needed for patient setup corrections, which were compared with shifts determined by the CBCT for evaluation. Both manual and automatic registrations were performed in order to compare the systematic registration errors. Fifty CBCT volumes were obtained from the eleven patients in fifty fractions for this pilot clinical study.For the CBCT images, the mean (±standard deviation) shifts between CBCT and planning CT from manual registration in left–right (LR), anterior–posterior (AP), and superior–inferior (SI) directions are 1.1 ± 1.2 mm, 2.1 ± 1.9 mm, 5.2 ± 3.6 mm, respectively. The mean deviation difference between shifts determined by CBCT and LP-CBCT images are 0.3 ± 0.5 mm, 0.5 ± 0.8 mm, 0.4 ± 0.3 mm, in LR, AP, and SI directions, respectively. The mean vector length of CBCT shift for all fractions is 6.1 ± 3.6 mm, and the mean vector length difference between CBCT and LP-CBCT for all fractions studied is 1.0 ± 0.9 mm. The automatic registrations yield similar results as manual registrations.The pilot clinical study shows that LP-CBCT localization offers comparable accuracy to CBCT localization for daily tumor positioning while reducing the projection number to 1/10 for patients receiving breath hold lung radiation treatment. The cluster projection sampling in this study also shows the feasibility of reconstructing fast 4D-CBCT from 1 min 3D-CBCT scan.

The Global Fire Atlas of individual fire size, duration, speed and direction

Abstract. Natural and human-ignited fires affect all major biomes, altering ecosystem structure, biogeochemical cycles and atmospheric composition. Satellite observations provide global data on spatiotemporal patterns of biomass burning and evidence for the rapid changes in global fire activity in response to land management and climate. Satellite imagery also provides detailed information on the daily or sub-daily position of fires that can be used to understand the dynamics of individual fires. The Global Fire Atlas is a new global dataset that tracks the dynamics of individual fires to determine the timing and location of ignitions, fire size and duration, and daily expansion, fire line length, speed, and direction of spread. Here, we present the underlying methodology and Global Fire Atlas results for 2003–2016 derived from daily moderate-resolution (500 m) Collection 6 MCD64A1 burned-area data. The algorithm identified 13.3 million individual fires over the study period, and estimated fire perimeters were in good agreement with independent data for the continental United States. A small number of large fires dominated sparsely populated arid and boreal ecosystems, while burned area in agricultural and other human-dominated landscapes was driven by high ignition densities that resulted in numerous smaller fires. Long-duration fires in boreal regions and natural landscapes in the humid tropics suggest that fire season length exerts a strong control on fire size and total burned area in these areas. In arid ecosystems with low fuel densities, high fire spread rates resulted in large, short-duration fires that quickly consumed available fuels. Importantly, multiday fires contributed the majority of burned area in all biomass burning regions. A first analysis of the largest, longest and fastest fires that occurred around the world revealed coherent regional patterns of extreme fires driven by large-scale climate forcing. Global Fire Atlas data are publicly available through http://www.globalfiredata.org (last access: 9 August 2018) and https://doi.org/10.3334/ORNLDAAC/1642, and individual fire information and summary data products provide new information for benchmarking fire models within ecosystem and Earth system models, understanding vegetation–fire feedbacks, improving global emissions estimates, and characterizing the changing role of fire in the Earth system.

PO-0845 What is the dosimetric benefit of daily position control imaging for prostate cancer radiotherapy?

PO-0845 What is the dosimetric benefit of daily position control imaging for prostate cancer radiotherapy?

Unravelling the contribution of early postseismic deformation using sub-daily GNSS positioning

After large earthquakes, parts of the fault continue to slip for days to months during the afterslip phase, a behaviour documented for many earthquakes. Yet, little is known about the early stage, i.e., from minutes to hours after the mainshock. Its detailed study requires continuous high-rate position time series close to the fault, and advanced signal processing to accurately extract the surface displacements. Here, we use refined kinematic precise point positioning processing to document the early postseismic deformation for three earthquakes along the South American subduction zone (2010 Mw8.8 Maule, Chile; 2015 Mw8.3 Illapel, Chile; 2016 Mw7.6 Pedernales, Ecuador). First, we show that early afterslip generates significant surface displacement as early as a few tens of minutes after the earthquake. Our analysis of the time series indicates that, over the first 36 hours, more than half of the displacement occurs within the first 12 hours, a time window often disregarded with daily positioning. Thus, estimates of coseismic offsets can be biased by more than 10% if early postseismic displacements are acknowledged as coseismic ones. Finally, these results highlight the difficulty to accurately evaluate the different contribution to the seismic cycle budget and thus the associated hazard on faults.

Population connectivity of pelagic megafauna in the Cuba-Mexico-United States triangle

The timing and extent of international crossings by billfishes, tunas, and sharks in the Cuba-Mexico-United States (U.S.) triangle was investigated using electronic tagging data from eight species that resulted in >22,000 tracking days. Transnational movements of these highly mobile marine predators were pronounced with varying levels of bi- or tri-national population connectivity displayed by each species. Billfishes and tunas moved throughout the Gulf of Mexico and all species investigated (blue marlin, white marlin, Atlantic bluefin tuna, yellowfin tuna) frequently crossed international boundaries and entered the territorial waters of Cuba and/or Mexico. Certain sharks (tiger shark, scalloped hammerhead) displayed prolonged periods of residency in U.S. waters with more limited displacements, while whale sharks and to a lesser degree shortfin mako moved through multiple jurisdictions. The spatial extent of associated movements was generally associated with their differential use of coastal and open ocean pelagic ecosystems. Species with the majority of daily positions in oceanic waters off the continental shelf showed the greatest tendency for transnational movements and typically traveled farther from initial tagging locations. Several species converged on a common seasonal movement pattern between territorial waters of the U.S. (summer) and Mexico (winter).