UC San Diego

Cuvier’s beaked whales are a deep-diving cetacean species known to forage in the submarine canyons of the Southern California Bight. Although this species is a top predator in deep-sea ecosystems, little is known about their social or foraging strategies because of their extreme diving behavior. In this analysis, time-difference-of-arrival (TDOA) localization is used to track the position of Cuvier’s beaked whales from echolocation clicks recorded on seafloor-mounted hydrophone arrays. This approach yielded 162 final tracks with estimated swim speeds of diving Cuvier’s beaked whales at one acoustic monitoring site from July 2021 to October 2022. The number of individual whales captured on a single track ranged from 1 to 7, with a mean of 2.24. Tracks including four or more individuals were captured most often during the day, with notable peaks in July 2021, February 2022, and July 2022. Three distinct diving behaviors were observed, differentiated by minimum depth, change in depth, and lateral movement: initial descent dive segments (1.657 ± 0.441 m/s), consistent trajectory dive segments (0.913 ± 0.596 m/s), and variable trajectory segments (1.298 ± 0.438 m/s). This long-term monitoring effort and TDOA localization approach collected data from Cuvier’s beaked whale foraging dives to reveal spatial use, group size, and diving behavior trends at our acoustic monitoring site. This extensive tracking dataset gives valuable insight into the social and foraging behavior at depth of Cuvier’s beaked whales offshore Southern California.