École Nationale Supérieure de
Techniques Avancées

Abstract

Prey predator interaction is a key factor to understanding the trophic cascades and ecosystems structure and balance. Biologging has considerably improved our knowledge of marine mammals and their interactions with their environment. Here we examine the performance of a new biologging tag - the μsonar recently developped at the Sea Mammal Research Unit - that uses active acoustics to provide information about their behavior and environment. Experiments in controlled basin have shown that the estimation of the length of insonified targets is reliable but depends on the species. We show that the parameters controlling size estimation are the target environment, orentation, biophysical properties, position in the beam and the detection threshold. Intercomparison with an optical sensor informs about sonar detection of small particles capabilities and estimates the limit size of detection at 500 μm. We discuss the target detection process and the complexity of defining a sampling volume based on the radiation pattern.