V-Track: Software for analysing and visualising animal movement from acoustic telemetry detections

The tagging of aquatic and semi-aquatic animals with acoustic transmitters and their detection by passive underwater receivers has gained huge popularity over the past decade. This technology offers researchers the opportunity to monitor the finite- to broad-scale movements of multiple individuals over many years; however, the sheer scale and spatial complexity of these datasets are often beyond the capabilities of routine database and spread-sheet applications. In the present paper, we describe software (V-Track) that greatly facilitates the assimilation, analysis and synthesis of animal-location data collected by underwater passive acoustic receivers. The principal features within V-Track are the behavioural event qualifier (BEQ) and the receiver-distance matrix (RDM) calculator. The BEQ identifies and catalogues horizontal movements from receiver detection data, or vertical movements from transmitter sensor data (depth or temperature). The RDM is generated from the geographical location of the acoustic receivers and is utilised by V-Track to illustrate the behavioural event information in a spatial context. V-Track is a package written within the R-programming language, and a graphical user interface is also provided. Here, we feature two case studies to demonstrate software functionality for defining and quantifying behaviour in acoustically tagged marine and freshwater vertebrates.