Behavioral responses of individual blue whales (Balaenoptera musculus) to mid-frequency military sonar
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 01, 2019
- Source ID
- 10.1242/jeb.190637
Entities
People
- Alison K. Stimpert
- Ann N. Allen
- Ari S. Friedlaender
- Brandon L. Southall
- Caroline Casey
- Catriona M Harris
- David E. Cade
- David J. Moretti
- Elliott L. Hazen
- Greg Schorr
- Jeremy A. Goldbogen
- John Calambokidis
- Selene Fregosi
- Shane Guan
- Stacy L. DeRuiter
Organizations
- Calvin University
- Marine Ecology and Telemetry Research
- National Marine Fisheries Service
- Naval Undersea Warfare Center
- Office of Naval Research
- Oregon State University
- San José State University
- Southwest Fisheries Science Center
- Stanford University
- United States Navy
- University of California
- University of St Andrews