Interpreting behavioural data from Radio-Acoustic Positioning Telemetry (RAPT) systems

Abstract

To detect behavioural patterns of individually tagged squid Loligo vulgaris reynaudii in a Radio-Acoustic Positioning Telemetry (RAPT) buoy array, trajectories reflecting the four dimensions of latitude, longitude, depth and time were plotted from data collected during field experiments in South Africa. Finding a continuous curve to represent the sampled trajectories required dealing with anisotropic precision and accuracy, nonuniform sampling rates and improbable outliers. A combination of an operator-controlled smoothing option of an approximating cubic spline and a weight factor assignment based on distance from the mass curve gave the most expedient results when compared with video recordings.

Keywords: corrective smoothing, Loligo vulgaris reynaudii, Radio-Acoustic Positioning Telemetry (RAPT), trajectories

African Journal of Marine Science 2005, 27(2): 395–399