ESR 42:133-149 (2020)  -  DOI: https://doi.org/10.3354/esr01044

ABSTRACT: Habitat use by the endangered Mediterranean sperm whale subpopulation remains poorly understood, especially in winter. The sustained presence of oceanographic autonomous underwater vehicles in the area presents an opportunity to improve observation effort, enabling collection of valuable sperm whale distribution data, which may be crucial to their conservation. Passive acoustic monitoring loggers were deployed on vertically profiling oceanographic gliders surveying the north-western Mediterranean Sea during winter 2012-2013 and June 2014. Sperm whale echolocation ‘usual click’ trains, characteristic of foraging activity, were detected and classified from the recordings, providing information about the presence of sperm whales along the glider tracks. Widespread presence of sperm whales in the north-western Mediterranean Sea was confirmed. Winter observations suggest different foraging strategies between the Ligurian Sea, where mobile and scattered individuals forage at all times of day, and the Gulf of Lion, where larger aggregations target intense oceanographic features in the open ocean such as fronts and mixing events, with reduced acoustic presence at dawn. This study demonstrates the ability to successfully observe sperm whale behaviour from passive acoustic monitoring gliders. We identified possible mission design changes to optimize data collected from passive acoustic monitoring glider surveys and significantly improve sperm whale population monitoring and habitat use.

KEY WORDS: Passive acoustic monitoring · PAM · Glider · Autonomous underwater vehicle · Habitat use · Mediterranean Sea · Sperm whale · Physeter macrocephalus

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Cite this article as: Cauchy P, Heywood KJ, Risch D, Merchant ND, Queste BY, Testor P (2020) Sperm whale presence observed using passive acoustic monitoring from gliders of opportunity. Endang Species Res 42:133-149. https://doi.org/10.3354/esr01044 Export citation Share:    Facebook - - linkedIn