Direct measurement of swimming and diving kinematics of giant Atlantic bluefin tuna (Thunnus thynnus)

Tunas possess a range of physiological and mechanical adaptations geared towards high performance swimming that are of considerable interest to physiologists, ecologists and engineers. Advances in biologging have provided significant improvements in understanding tuna migrations and vertical movement patterns, yet our understanding of the locomotion and swimming mechanics of these fish under natural conditions is limited. We equipped Atlantic bluefin tuna (Thunnus thynnus) with motion sensitive tags and video cameras to quantify the gaits and kinematics used by wild fish. Our data reveal significant variety in the locomotory activity of Atlantic bluefin tuna kinematics, ranging from continuous locomotion to two types of intermittent locomotion. The tuna sustained swimming speeds in excess of 3 m s-1 (1.2 body lengths s-1), while beating their tail at a frequency of ~1 Hz. While diving, some descents were entirely composed of passive glides, with slower descent rates featuring more glid...