Beaked whale foraging behavior during 12 kHz multibeam mapping survey off southern California coast

Abstract

To create appropriate marine mammal protection regulations, a better understanding of potential impacts of anthropogenic noise on marine mammals is needed. To contribute to the growing body of knowledge on this subject, echolocation clicks of foraging Cuvier's beaked whales were detected on the Southern California Antisubmarine Warfare Range (SOAR) hydrophones during 12 kHz multibeam echosounder (MBES) ocean mapping surveys in 2017 and 2019, and assembled into foraging events called group vocal periods (GVPs). Four GVP characteristics were analyzed Before, During, and After the MBES surveys to assess differences in foraging behavior with respect to the mapping activity. The number of GVP per hour increased During and After MBES surveys compared with Before. There were no other differences between non-MBES and MBES periods for the other characteristics: number of clicks per GVP, GVP duration, and click rate. These results indicate that the animals did not leave the range or stopforaging during MBES activity. [Funded by NOAA Grant No. NA15NOS4000200 through the UNH Joint Hydrographic Center.]