Heart Rate and R–R Interval Recording in a Bottlenose Dolphin: Toward a Keeper-Led Framework for HRV-Based Welfare Assessment

Yumi Shimozato, Kensuke Yamada, Yu Tsuchiya, Miyui Chiba, Risa Shigaki, Masayuki Hosono

Monitoring physiological states in managed animals is important for health management and welfare assessment. Heart rate variability (HRV) may provide welfare-relevant information on autonomic regulation, but practical keeper-led approaches for obtaining cardiac data during routine husbandry remain limited in zoos and aquariums.
To address this gap, we propose a keeper-led framework in which aquarium animal-care teams repeatedly collect HR and R–R interval data during routine husbandry. Research partners analyze the cardiac data, using available respiratory, behavioral, and health information as context for interpretation, and return the findings to animal-care practice.
We examined whether HR and R–R interval recordings could be obtained from a bottlenose dolphin (Tursiops truncatus) during voluntary routine husbandry training.
A commercially available belt-mounted sensor was used while the dolphin maintained a stationary dorsal floating posture at the water surface. Usable HR and R–R interval recordings were obtained, demonstrating feasibility in a cooperative husbandry setting. Representative recordings showed beat-to-beat variation and intermittently prolonged R–R intervals, with corresponding fluctuations in derived HR. Synchronized video annotations of respiratory, behavioral, and training-related events provided context.
These observations are descriptive and do not establish specific autonomic, affective, or welfare states. However, they provide a basis for HRV analyses and repeated, context-informed investigation of autonomic patterns in relation to stress-related responses, arousal, recovery, and relatively settled physiological conditions. This study presents the initial recording and implementation component of the framework. Repeated recordings under comparable conditions may support development of individual baseline profiles and context-informed HRV-based animal welfare indicators in zoological and aquarium settings.