What we refer to as marine predators include large pelagic fishes (e.g., sharks and billfish), marine mammals (e.g., seals), seabirds (e.g., penguins), and sea turtles. Despite their differences in taxonomic groups, these animals typically have large bodies, roam widely, and play crucial roles as top consumers in marine food chains. Their ecology is poorly understood due to the challenges of studying them in the open ocean. Furthermore, many marine predators are negatively affected by increasing human activities and climate change.

In the past, studying the behavior and physiology of marine predators in the wild was nearly impossible. However, recent advancements in biologging technology(*), or the use of miniaturized animal-borne sensors, have made this possible. We use biologging technology as our primary research tool. Among various marine predators, we focus primarily on pelagic sharks, studying them both in Japan (Kochi, Okinawa, and our hometown Hayama) and in overseas locations (e.g., Taiwan, Australia, and Canada). We also study seals and some seabirds. Our approach combines biologging data from wild marine predators with information from other species in the literature and remotely sensed environmental data. By doing so, we aim to understand the ecological and evolutionary factors influencing the behavior and physiology of marine predators, as well as how they respond to climate changes and other environmental changes associated with human activities.

In biologging, while effectively utilizing current devices is important, the development of new devices is even more crucial. Therefore, we collaborate with several manufacturers and continuously strive to record truly novel data from free-swimming marine predators.

↑Biologging in action. From Watanabe and Papastamatiou (2023) Annu. Rev. Anim. Biosci.

(*)Please refer to our review article ”Biologging and biotelemetry: tools for understanding the lives and environments of marine animals" about history, current states, and future perspectives of biologging technology.