Field testing a novel high residence positioning system for monitoring the fine‐scale movements of aquatic organisms

Abstract

Acoustic telemetry is an important tool for studying the behaviour of aquatic organisms in the wild.VEMCO high residence (HR) tags and receivers are a recent introduction in the field of acoustic telemetry and can be paired with existing algorithms (e.g. VEMCO positioning system [VPS]) to obtain high‐resolution two‐dimensional positioning data.Here, we present results of the first documented field test of a VPS composed of HR receivers (hereafter, HR‐VPS). We performed a series of stationary and moving trials with HR tags (mean HR transmission period = 1.5 s) to evaluate the precision, accuracy and temporal capabilities of this positioning technology. In addition, we present a sample of data obtained for five European perch Perca fluviatilis implanted with HR tags (mean HR transmission period = 4 s) to illustrate how this technology can estimate the fine‐scale behaviour of aquatic animals.Accuracy and precision estimates (median [5th–95th percentile]) of HR‐VPS positions for all stationary trials were 5.6 m (4.2–10.8 m) and 0.1 m (0.02–0.07 m), respectively, and depended on the location of tags within the receiver array. In moving tests, tracks generated by HR‐VPS closely mimicked those produced by a handheld GPS held over the tag, but these differed in location by an average of ≈9 m.We found that estimates of animal speed and distance travelled for perch declined when positional data for acoustically tagged perch were thinned to mimic longer transmission periods. These data also revealed a trade‐off between capturing real nonlinear animal movements and the inclusion of positioning error.Our results suggested that HR‐VPS can provide more representative estimates of movement metrics and offer an advancement for studying fine‐scale movements of aquatic organisms, but high‐precision survey techniques may be needed to test these systems.

Behaviour of endangered European eels in proximity to a dam during downstream migration: Novel insights using high accuracy 3D acoustic telemetry

“…The accuracy in the present study was better than, or equivalent to, that reported in comparable studies using commercial positioning systems. For example, Espinoza, Farrugia, Webber, et al () showed that the mean positional accuracy of VEMCO Positioning System (VPS) estimates from a stationary transmitter deployed at several locations within the receiver array was 2.64 ± 2.32 m. In comparison, Guzzo et al () found that the accuracy estimates of HR‐VPS positions for all stationary trials was 5.6 m. Biesinger et al () demonstrated a positional accuracy of approximately 2 m. This improved accuracy could be explained by (a) the positioning of the receiver to the nearest centimetre using a theodolite for x and y coordinates, and using a decametre for z , and (b) the real‐time measurement of water temperature to continuously correct the speed of sound in water at the exact moment of acoustic signal reception. This was possible using the intern thermic sensor included in Thelma Biotel receivers.…”

“…To position tagged aquatic animals accurately without links to receivers, analysis of Time Difference Of Arrival (TDOA) has been developed by telemetry manufacturers. Unfortunately, scientific studies using this methodology have not provided sufficient details of the technical methods and calculations to enable reported experiments to be reproduced (see for instance Espinoza, Farrugia, Webber, Smith, & Lowe, ; Guzzo et al, ; Roy et al, ). Moreover, until recently, access to this methodology was via a paid service or software, not via open access services (Baktoft, Gjelland, Økland, & Thygesen, ).…”

“…that the mean positional accuracy ofVEMCO Positioning System (VPS) estimates from a stationary transmitter deployed at several locations within the receiver array was 2.64 ± 2.32 m. In comparison,Guzzo et al (2018) found that the accuracy estimates of HR-VPS positions for all stationary trials was 5.6 m Biesinger et al (2013). demonstrated a positional accuracy of approximately 2 m. This improved accuracy F I G U R E 4 Cumulative quantile of error location distribution for test transmitter #1 (blue line) and test transmitter #2 (red line).…”

Acoustic‐telemetry payload control of an autonomous underwater vehicle for mapping tagged fish

“…The quality of synthetic aperture position estimates is dependent first on the precision of the timing and on geometry of the aperture based on theory of minimizing the intersect area of possible reception spheres or circles (termed dilution of precision, Schau and Robinson ; Pascazio and Fornaro ). Geometry is confirmed in practice as the most consistent determinant of quality in estimates from moored array hydrophone positioning systems (Meckley et al ; Romain et al ; Steel et al ; Guzzo et al ) and for those made by a towed hydrophone (Nielsen et al ).…”

The influence of system settings on positioning accuracy in acoustic telemetry, using the YAPS algorithm.

“…A frequently used signal encoding is pulse position modulation (PPM), where the ID is encoded in the time interval between 8 to 10 transmitted pulses, similar to Morse code [9,10]. Since a PPM transmission takes 3 to 5 seconds [11], simultaneous transmissions of different animals can cause signal collision, which results in incomplete or corrupted transmissions. Hence, the amount of fish that will be present simultaneously in the study area limits the allowable burst interval.…”