Abstract
Long-term quantitative observations are essential for the conservation of the whale shark (Rhincodon typus), which requires a long time to grow and mature. In this study, a data logger was attached to a mature male whale shark that had been maintained in captivity for over 29 years at the Okinawa Churaumi Aquarium in Japan. Because long-term rearing of whale sharks in captivity is desirable, the effects of water temperature and light on the swimming behavior of the captive whale shark were investigated. Tail-beat frequencies (TBFs), activity levels, and frequencies of clasper crosses, which are thought to be a mating-like behavior, were calculated from the swimming data. In all seasons, TBF, swimming speed, and activity level of the shark were 4%–20% less during the nighttime than during the daytime, particularly at cool water temperatures (≤23.6°C). Furthermore, approximately 90% of the clasper crosses occurred during the daytime. These results indicate that the shark is active during the daytime, engaging in activities such as mating behavior. In contrast, during the nighttime, it rests while swimming, slowing down the beat of its caudal fin and lowering swimming speed to conserve energy. Therefore, we conclude that this individual has adopted this diurnal rhythm to adapt to its current rearing environment.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call