UC Berkeley

Migration is an integral feature of modern mysticete whale ecology, and one that intricately links their behavior to the processes which shape the spatiotemporal distributions of oceanic productivity. Each year, mysticete whales travel thousands of miles to access seasonally productive, high-latitude waters where they feed in the summer before retreating to warm, low-latitude waters to breed and raise their calves in the winter. As the spatial and temporal distribution of oceanic productivity has shifted over geological timeframes, the changing demands of migration may have played key roles in shaping mysticete evolutionary history. And because mysticetes must rely on the most productive of waters to sustain their great mass, understanding how their migration routes have changed through time may also provide unique insight into productivity patterns in the ancient ocean.

Understanding what role migration may have played in mysticete evolution and using whale movements as a means of understanding prehistoric productivity patterns depends on having a reliable means of measuring migratory behavior in deep time, yet little is currently known of prehistoric whale migrations. My research seeks to address this knowledge gap via isotopic analysis of coronulids, the commensal barnacles which live attached to the skin of some mysticete lineages. As these barnacles grow, each new shell layer preserves an isotopic signature of the water in which it was formed, providing a mechanism by which to reconstruct the migration of the host whale. I first verify the reliability of the method by demonstrating that isotopic information from modern coronulids accurately reflects the known migratory paths of their host whales. Next, I show that migration was a widespread phenomenon by the Pleistocene, where every sampled population indicates evidence of migration. I then combine isotopic analysis with paleoceanographic modeling to constrain the migratory paths taken by several Pleistocene whales. Along the way, I discuss the implications of an unexpected and unique fossil discovery that could alter our understanding of one mysticete lineage’s evolutionary history.