Departmental Bulletin Paper Evaluation of wave drag on bottlenose dolphin Tursiops truncatus from swimming effort

Akiyama, Yu  ,  Matsuda, Yoshio  ,  Sakurai, Natsuko  ,  Sato, Katsufumi

38 ( 1 )  , pp.42 - 46 , 2015-07 , International Coastal Research Center, Atmosphere and Ocean Research Institute, the University of Tokyo
When animals move across the water surface, they push out surrounding water, creating waves. This work of wave formation is considered the largest drag component at the water surface and is known as wave drag. In order to avoid wave drag, most marine mammals travel submerged over longer distances and minimize the time spent swimming at the surface. We attached an accelerometer to a trained bottlenose dolphin and evaluated the effect of wave drag from the dolphin's swimming speed and stroking efforts such as stroke frequency and body amplitude. We found that the body amplitude was significantly larger at the surface than at a depth of 3 m within a given speed range; however, the difference was not clear enough to quantitatively evaluate the effect of wave drag. The reasons might be due to the limited size of the pool used in this study. Thus a more controlled experiment with longer swimming distance, a deeper pool, and better control of the dolphin's swimming speed is required to further our understanding of the effect of wave drag on dolphins.

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