RT Journal Article SR Electronic T1 Memory and resource tracking drive blue whale migrations JF Proceedings of the National Academy of Sciences JO Proc Natl Acad Sci USA FD National Academy of Sciences SP 5582 OP 5587 DO 10.1073/pnas.1819031116 VO 116 IS 12 A1 Abrahms, Briana A1 Hazen, Elliott L. A1 Aikens, Ellen O. A1 Savoca, Matthew S. A1 Goldbogen, Jeremy A. A1 Bograd, Steven J. A1 Jacox, Michael G. A1 Irvine, Ladd M. A1 Palacios, Daniel M. A1 Mate, Bruce R. YR 2019 UL //www.hmclip.net/content/116/12/5582.abstract AB The causes and consequences of animal migration have received substantial research attention, yet the mechanisms underlying this global phenomenon remain largely untested in marine systems. By combining 10 years of satellite tracking data on blue whales with simultaneous remotely-sensed oceanographic measurements in the North Pacific, we demonstrate that both long-term memory and resource tracking play key roles in the long-distance migrations of marine megafauna. These findings have important implications for long-lived species across systems and taxa, as long-range migrants conditioned by historical environmental processes may struggle in response to rapid environmental change. Finally, our study reveals that ecological theory of animal migrations is conserved across marine and terrestrial systems.In terrestrial systems, the green wave hypothesis posits that migrating animals can enhance foraging opportunities by tracking phenological variation in high-quality forage across space (i.e., “resource waves”). To track resource waves, animals may rely on proximate cues and/or memory of long-term average phenologies. Although there is growing evidence of resource tracking in terrestrial migrants, such drivers remain unevaluated in migratory marine megafauna. Here we present a test of the green wave hypothesis in a marine system. We compare 10 years of blue whale movement data with the timing of the spring phytoplankton bloom resulting in increased prey availability in the California Current Ecosystem, allowing us to investigate resource tracking both contemporaneously (response to proximate cues) and based on climatological conditions (memory) during migrations. Blue whales closely tracked the long-term average phenology of the spring bloom, but did not track contemporaneous green-up. In addition, blue whale foraging locations were characterized by low long-term habitat variability and high long-term productivity compared with contemporaneous measurements. Results indicate that memory of long-term average conditions may have a previously underappreciated role in driving migratory movements of long-lived species in marine systems, and suggest that these animals may struggle to respond to rapid deviations from historical mean environmental conditions. Results further highlight that an ecological theory of migration is conserved across marine and terrestrial systems. Understanding the drivers of animal migration is critical for assessing how environmental changes will affect highly mobile fauna at a global scale.