Propagation distances and sound properties of the antennal rasps produced by spiny lobsters (Palinurus elephas) in European coastal waters

Abstract

Spiny lobsters (Palinurus elephas) have been overfished in European waters, and adult breeders are now scarce. Our recent study highlighted the high acoustic potential of this species, which can emit loud broadband pulse trains, called “antennal rasps,” with peak-to-peak source levels (estimated at 1 m from the source) above 160 dB re 1 μPa² [Jezequel et al., Marine Ecology Progress Series 615 (2019)]. These acoustic properties imply that these sounds could be detected during in situ passive acoustic monitoring. However, before using a such tool, we need to understand how antennal rasps propagate in situ and at what distance they could be detected above the ambient noise. To answer these questions, we recorded spiny lobster antennal rasps in the Iroise Sea (Brittany, France). We used a linear array of 8 hydrophones, with distances between animals and receivers ranging from 0.5 m to 100 m. We recorded antennal rasps from 38 individuals of various sizes. Our results demonstrate that large spiny lobsters can be detected at 100 m, and that sound properties might be directly influenced by the size of the individuals.