Leroy Emmanuelle C, Samaran Flore, Bonnel Julien, Royer Jean-Yves
University of Brest and Centre National de la Recherche Scientifique, Laboratoire Géosciences Océan, Institut Universitaire Européen de la Mer, 29280 Plouzané, France.
Centre National de la Recherche Scientifique Unité Mixte de Recherche 6285 Lab-STICC, Ecole Nationale Supérieure de Techniques Avancées, Bretagne, 29806 Brest, France.
J Acoust Soc Am. 2017 Sep;142(3):1413. doi: 10.1121/1.5001056.
Since passive acoustic monitoring is widely used, unidentified acoustic signals from marine mammals are commonly reported. The signal characteristics and emission patterns are the main clues to identify the possible sources. In this study, the authors describe two previously unidentified sounds, recorded at up to five widely-spaced sites (30 × 30 degree area) in the southern Indian Ocean, in 2007 and between 2010 and 2015. The first reported signal (M-call) consists of a single tonal unit near 22 Hz and lasting about 10 s, repeated with an interval longer than 2 min. This signal is only detected in 2007. The second signal (P-call) is also a tonal unit of 10 s, repeated every 160 s, but at a frequency near 27 Hz. Its yearly number increased greatly between 2007 and 2010, and moderately since then. Based on their characteristics and seasonal patterns, this study shows that both signals are clearly distinct from any known calls of blue whale subspecies and populations dwelling in the southern Indian Ocean. However, they display similarities with blue whale vocalizations. More particularly, the P-call can be mistaken for the first tonal unit of the Antarctic blue whale Z-call.
由于被动声学监测被广泛应用，来自海洋哺乳动物的未识别声学信号经常被报道。信号特征和发射模式是识别可能来源的主要线索。在本研究中，作者描述了2007年以及2010年至2015年期间在印度洋南部多达五个间隔较远的地点（30×30度区域）记录到的两种此前未识别的声音。首次报道的信号（M叫声）由一个接近22赫兹的单音调单元组成，持续约10秒，以超过2分钟的间隔重复出现。该信号仅在2007年被检测到。第二个信号（P叫声）也是一个10秒的音调单元，每160秒重复一次，但频率接近27赫兹。其年度数量在2007年至2010年间大幅增加，此后有所增加。基于它们的特征和季节性模式，本研究表明这两种信号与居住在印度洋南部的蓝鲸亚种和种群的任何已知叫声明显不同。然而，它们与蓝鲸的发声表现出相似性。更具体地说，P叫声可能会被误认为是南极蓝鲸Z叫声的第一个音调单元。
