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

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) while 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-foraging 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, feeding) were conducted. This included exper...