Behavioral responses of individual blue whales (Balaenoptera musculus) to mid-frequency military sonar

Brandon Southall, Stacy DeRuiter, Ari Friedlaender, Alison Stimpert, Jeremy Goldbogen, Elliot Hazen, Caroline Casey, Selene Fregosi, Dave Cade, Ann Allen, Catriona M Harris, Greg Schorr, Dave Moretti, Shane Guan, John Calambokidis

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22 Citations (Scopus)
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Abstract

This study measured the degree of behavioral responses in blue whales (Balaenoptera musculus) to controlled noise exposure off the southern California coast. High-resolution movement and passive acoustic data were obtained from non-invasive archival tags (n=42) whereas surface positions were obtained with visual focal follows. Controlled exposure experiments (CEEs) were used to obtain direct behavioral measurements before, during and after simulated and operational military mid-frequency active sonar (MFAS), pseudorandom noise (PRN) and controls (no noise exposure). For a subset of deep-feeding animals (n=21), active acoustic measurements of prey were obtained and used as contextual covariates in response analyses. To investigate potential behavioral changes within individuals as a function of controlled noise exposure conditions, two parallel analyses of time-series data for selected behavioral parameters (e.g. diving, horizontal movement and feeding) were conducted. This included expert scoring of responses according to a specified behavioral severity rating paradigm and quantitative change-point analyses using Mahalanobis distance statistics. Both methods identified clear changes in some conditions. More than 50% of blue whales in deep-feeding states responded during CEEs, whereas no changes in behavior were identified in shallow-feeding blue whales. Overall, responses were generally brief, of low to moderate severity, and highly dependent on exposure context such as behavioral state, source-to-whale horizontal range and prey availability. Response probability did not follow a simple exposure–response model based on received exposure level. These results, in combination with additional analytical methods to investigate different aspects of potential responses within and among individuals, provide a comprehensive evaluation of how free-ranging blue whales responded to mid-frequency military sonar.
Original languageEnglish
Article numberjeb190637
Number of pages15
JournalJournal of Experimental Biology
Volume222
Early online date4 Mar 2019
DOIs
Publication statusPublished - Mar 2019

Keywords

  • Sonar
  • Marine Mammal
  • Blue whale
  • Behavioral response
  • Endangered
  • Context

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