Source level estimation of two blue whale subspecies in southwestern Indian Ocean

• Published in: The Journal of the Acoustical Society of America
• Main Authors: Samaran, Flore, Guinet, Christophe, Adam, Olivier, Motsch, Jean-François, Cansi, Yves
• Other Authors: Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Détection et de Géophysique (CEA) (LDG), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: geo; hist; Antarctic; Indian; Antarc*; Blue whale
• Online Access: https://doi.org/10.1121/1.3409479; https://hal.archives-ouvertes.fr/hal-00528213

International audience Blue whales produce intense, stereotypic low frequency calls that are particularly well suited for transmission over long distances. Because these calls vary geographically, they can be used to gain insight into subspecies distribution. In the Southwestern Indian Ocean, acoustic data from a triad of calibrated hydrophones maintained by the International Monitoring System provided data on blue whale calls from two subspecies: Antarctic and pygmy blue whales. Using time difference of arrival and least-squares hyperbolic methods, the range and location of calling whales were determined. By using received level of calls and propagation modeling, call source levels of both subspecies were estimated. The average call source level was estimated to 179 +/- 5 dB re 1 mu Pa-rms at 1 m over the 17-30 Hz band for Antarctic blue whale and 174 +/- 1 dB re 1 mu Pa-rms at 1 m over the 17-50 Hz band for pygmy blue whale. According to previous estimates, slight variations in the source level could be due to inter-individual differences, inter-subspecies variations and the calculation method. These are the first reported source level estimations for blue whales in the Indian Ocean. Such data are critical to estimate detection ranges of calling blue whales. (C) 2010 Acoustical Society of America