Seasonal and Diel Vocalization Patterns of Antarctic Blue Whale (Balaenoptera musculus intermedia) in the Southern Indian Ocean: A Multi-Year and Multi-Site Study

PLoS One. 2016 Nov 9;11(11):e0163587. doi: 10.1371/journal.pone.0163587. eCollection 2016.

Abstract

Passive acoustic monitoring is an efficient way to provide insights on the ecology of large whales. This approach allows for long-term and species-specific monitoring over large areas. In this study, we examined six years (2010 to 2015) of continuous acoustic recordings at up to seven different locations in the Central and Southern Indian Basin to assess the peak periods of presence, seasonality and migration movements of Antarctic blue whales (Balaenoptera musculus intermedia). An automated method is used to detect the Antarctic blue whale stereotyped call, known as Z-call. Detection results are analyzed in terms of distribution, seasonal presence and diel pattern of emission at each site. Z-calls are detected year-round at each site, except for one located in the equatorial Indian Ocean, and display highly seasonal distribution. This seasonality is stable across years for every site, but varies between sites. Z-calls are mainly detected during autumn and spring at the subantarctic locations, suggesting that these sites are on the Antarctic blue whale migration routes, and mostly during winter at the subtropical sites. In addition to these seasonal trends, there is a significant diel pattern in Z-call emission, with more Z-calls in daytime than in nighttime. This diel pattern may be related to the blue whale feeding ecology.

MeSH terms

  • Acoustics
  • Animal Migration
  • Animals
  • Antarctic Regions
  • Balaenoptera / classification
  • Balaenoptera / physiology*
  • Circadian Rhythm*
  • Geography
  • Indian Ocean
  • Oceanography
  • Population Dynamics
  • Reproducibility of Results
  • Seasons*
  • Sound Spectrography / methods*
  • Species Specificity
  • Vocalization, Animal / physiology*

Grants and funding

Deployment and recovery cruises were funded by the French Polar Institute (IPEV; MD174/175, MD185, MD189, MD193, MD197, MD200, MD201 cruises) and by NOAA/PMEL and INCOIS (SK 307). Additional support for the acoustic experiments was provided by the Institut National des Sciences de l’Univers of CNRS. E.C.L. was supported by a Ph.D. fellowship from the University of Brest and from the Regional Council of Brittany (Conseil Régional de Bretagne). Moorings and hydrophones were funded by the Regional Council of Brittany (CPER). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.