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

1. Acoustic telemetry is an important tool for studying the behaviour of aquatic organisms in the wild. 2. 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. 3. 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. 4. 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 approximate to 9m. 5. 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. 6. 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.