Cuvier's Beaked Whale Presence Relative to Vertical and Temporal
Variability of Oceanographic Conditions in the Southern California Bight
Abstract
The oceanographic conditions of the Southern California Bight (SCB)
dictate the distribution and abundance of prey resources and therefore
the presence of mobile predators, such as Cuvier’s beaked whales
(Ziphius cavirostris). Cuvier’s beaked whales are deep-diving
odontocetes that spend a majority of their time foraging at depth. Due
to their cryptic behavior, little is known about how they respond to
seasonal and interannual changes in their environment. This study
utilizes passive acoustic data recorded from two sites within the SCB to
explore the oceanographic conditions that Cuvier’s beaked whales appear
to favor. Utilizing optimum multiparameter analysis, modeled temperature
and salinity data are used to identify and quantify these source waters:
Pacific Subarctic Upper Water (PSUW), Pacific Equatorial Water (PEW),
and Eastern North Pacific Central Water (ENPCW). The interannual and
seasonal variability in Cuvier’s beaked whale presence was related to
the variability in El Niño Southern Oscillation events and the fraction
and vertical distribution of the three source waters. Cuvier’s beaked
whale acoustic presence was highest during the winter and spring and
decreased during the late summer and early fall. These seasonal
increases occurred at times of increased fractions of PEW in the
California Undercurrent and decreased fractions of ENPCW in surface
waters. Interannual increases in Cuvier’s beaked whale presence occurred
during El Niño events. These results establish a baseline understanding
of the oceanographic characteristics that correlate with Cuvier’s beaked
whale presence in the SCB. Furthering our knowledge of this elusive
species is key to understanding how anthropogenic activities impact
Cuvier’s beaked whales.