Physical Sciences and Mathematics Commons^™

Blue Whale Visual And Acoustic Encounter Rates In The Southern California Bight, Erin M. Oleson, John Calambokidis, Jay Barlow, John A. Hildebrand

United States Department of Commerce: Staff Publications

The relationship between blue whale (Balaenoptera musculus) visual and acoustic encounter rates was quantitatively evaluated using hourly counts of detected whales during shipboard surveys off southern California. Encounter rates were estimated using temporal, geographic, and weather variables within a generalized additive model framework. Visual encounters (2.06 animals/h, CV = 0.10) varied with subregion, Julian day, time of day, and year. Acoustic encounters of whales producing pulsed A and tonal B call sequences (song; 0.65 animals/h, CV = 0.06) varied by Julian day, survey mode (transit or stationary), and subregion, and encounters of whales producing downswept (D) calls (0.41 …