Movements and Oceanographic Associations of Large Pelagic Fishes in the North Atlantic Ocean

Camrin Braun, Ph.D., 2018
Simon Thorrold

Highly migratory marine fishes support valuable commercial fisheries worldwide. Yet, many target species have proven difficult to study due to long-distance migrations and deep diving. Despite the dominance of oceanographic features, the biophysical interactions in the ocean remain poorly understood. This leads to a paucity of knowledge on oceanographic associations of pelagic fishes and hinders management efforts. In this thesis, I developed a model framework to characterize the biophysical interactions influencing animal behavior and species' ecology in the open ocean. An observation-based likelihood framework was combined with a Bayesian state-space model to improve geolocation estimates for archival-tagged basking shark and swordfish datasets using oceanographic profile data. Finally, I designed a synergistic analysis of 3D shark movements and satellite observations to quantify the interaction of blue sharks with mesoscale oceanography. Eddies influenced blue shark movements and facilitated connectivity between deep scattering layer communities and deep-diving, epipelagic predators. Together, these studies demonstrate the breadth and depth of information that can be garnered through the integration of traditional animal tagging and oceanographic research with high-resolution oceanographic model and remote sensing datasets, the product of which provides a transformative view of the biophysical interactions occurring in and governing the structure of the pelagic ocean.