A combination of gyroscope and accelerometer for identifying alternative feeding behaviours in fish

Abstract

Abstract We examined whether we could identify the feeding behaviours of the trophic generalist fish Epinephelus ongus on different prey types (crabs and fish) using a data-logger that incorporated a 3-axis gyroscope and a 3-axis accelerometer. Feeding behaviours and other burst behaviours, including escape responses, intraspecific interactions, and routine movements, were recorded from six E. ongus individuals using data-loggers sampling at 200 Hz, and were validated by simultaneously recorded video images. For each data-logger record, we extracted 5 seconds of data when any of the 3-axis accelerations exceeded absolute 2.0 G, to capture all feeding behaviours and other burst behaviours. Each feeding behaviour was then identified using a combination of parameters that were derived from the extracted data. Using decision trees with the parameters, high true identification rates (87.5% for both feeding behaviours) with low false identification rates (5% for crab-eating and 6.3% for fish-eating) were achieved for both feeding behaviours.