UC San Diego

Although sperm whales are a cosmopolitan species, male and female sperm whales are sexually dimorphic, and the sexes have differences in behavior and habitat preference that result in differences in their distribution and seasonality. Understanding the complex spatiotemporal distribution patterns and demographic composition can be difficult with traditional, logistically challenging shipboard methods given the vast distances and depths these animals travel. Since sperm whales produce highly distinctive echolocation clicks while foraging and navigating, they’re excellent candidates for passive acoustic monitoring (PAM), an alternative method to eavesdrop on these deep-diving animals. Here we show the utility of PAM as a robust tool for advancing our understanding of sperm whale ecology. This study incorporates acoustic data from over 40 recording sites across the northern hemisphere, yielding valuable insights into demographics, acoustic density estimation, and the identification of high-use areas and habitat associations. In remote regions, PAM has enabled us to identify areas where sperm whales are adapting to changing environmental conditions by expanding their potential range in response to climate change, exemplified by observations in the eastern Canadian Arctic. Furthermore, our findings challenge conventional assumptions about male and female preferred habitats, as evidenced by the presence of females in high-latitude regions like the Gulf of Alaska and Bering Sea/Aleutian Islands. Our long-term PAM efforts have significantly expanded our knowledge of demographic specific presence, spatiotemporal distribution, acoustic density, and habitat associations of sperm whales. This underscores the importance of tailored conservation and management strategies that account for demographic variations for effective stewardship of this endangered species.