Processing and analysis of bioacoustic signals in the southern Indian Ocean

Blue whales (Balaenoptera musculus ssp) were brought to the brink of extinction during whaling and are still endangered today. In the southern Indian Ocean, a remote region subject to extreme weather conditions, passive acoustics quickly became the preferred method for monitoring these large marine...

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Bibliographic Details
Main Author: Torterotot, Maëlle
Other Authors: Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne occidentale - Brest, Jean-Yves Royer, Flore Samaran
Format: Doctoral or Postdoctoral Thesis
Language:French
Published: HAL CCSD 2020
Subjects:
Blue whale
Southern Indian Ocean
Bioacoustics
Passive acoustic monitoring
Baleine bleue
Océan Indien austral
Bioacoustique
Surveillance acoustique passive
[SPI.OTHER]Engineering Sciences [physics]/Other
Antarctic
Austral
Baleine
Baleinière
Bleue
Indian
la Baleine
Antarc*
Antarctique*
Balaenoptera musculus
Online Access:https://theses.hal.science/tel-03372735
https://theses.hal.science/tel-03372735/document
https://theses.hal.science/tel-03372735/file/These-2020-3M-Acoustique_sous_marine_et_traitement_du_signal-TORTEROTOT_Maelle.pdf
Description
Summary:Blue whales (Balaenoptera musculus ssp) were brought to the brink of extinction during whaling and are still endangered today. In the southern Indian Ocean, a remote region subject to extreme weather conditions, passive acoustics quickly became the preferred method for monitoring these large marine mammals. This thesis is based on acoustic data recorded from 2010 to 2018 by a large hydrophone network in the southern Indian Ocean. An automatic detection algorithm, whose performance was thoroughly evaluated beforehand, is applied to detect the stereotyped and non-stereotyped calls (D-calls) of Antarctic blue whales and Australian and Madagascan pygmy blue whales. Detections of stereotyped calls refine the spatial and seasonal distributions previously described in the southern Indian Ocean and reveal that Antarctic and pygmy blue whales use this region in very different ways. Comparison between the geographical presence of stereotyped and nonstereotyped calls suggests a change in the acoustic behavior of blue whales between subtropical and subantarctic regions. Finally, the characterization of the southern Indian Ocean soundscape indicates that anthropogenic signals are prevalent, even in remote areas. La baleine bleue (Balaenoptera musculus ssp) a été menée au bord de l’extinction durant la chasse baleinière et est aujourd’hui toujours en danger. Dans l’océan Indien austral, une région reculée et soumise à des conditions météorologiques extrêmes, l’utilisation de l’acoustique passive s’est rapidement imposée pour le suivi de ces grands mammifères marins. Cette thèse repose sur des enregistrements acoustiques acquis de 2010 à 2018 par un réseau d’hydrophones de grande envergure situé dans l’océan Indien austral. Un algorithme de détection automatique, dont les performances sont préalablement évaluées, est appliqué pour détecter les vocalisations stéréotypées et non-stéréoptyées (D-calls) des baleines bleues Antarctique et des baleines bleues pygmées d’Australie et de Madagascar. Les détections des vocalisations ...

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