UC San Diego

The distribution of highly mobile, top marine predators such as cetaceans is largely driven by oceanographic conditions that shape foraging grounds and modulate the abundance and distribution of prey resources. However, due to their oceanic habitat and cryptic behavior, little is known on how deep-diving foragers respond to changes in the water column. This study used passive acoustic data collected at two sites in the Southern California Bight along with environmental data to examine spatial and temporal patterns of Cuvier’s beaked whale (Ziphius cavirostris) occurrence in relation to oceanographic conditions over time. Here, I show that seasonal changes in oceanographic conditions and mesoscale dynamics influence seasonal patterns of Cuvier’s beaked whale presence across the study region. Specifically, I found that Cuvier’s beaked whales were more likely encountered in winter and spring when water temperature, salinity, and relative vorticity at the surface were low while temperature at 200 m were high. Consequently, fluctuations in detection rates of Cuvier’s beaked whales from year-to-year and between sites suggest that abrupt changes in these oceanographic variables seem to influence interannual variability in seasonal patterns of presence. These results provide baseline data on spatio-temporal distribution of Cuvier’s beaked whales in the Southern California Bight and emphasize the value of coupling long-term acoustic monitoring with environmental data to better understand elusive cetacean species’ habitat use and relationship to oceanographic changes, which may aid the development of management strategies related to global climate change and anthropogenic noise.