2012 Volume 80 Issue 2 Pages 177-185
The authors conducted a swimming experiment in the field using cultured masu salmon (Oncorhynchus masou masou) fingerlings in order to study the relationship between tail beats and swimming speed. The experimental equipment used was a stamina tunnel with a rectangular cross-section channel, which was installed at a local fishway. The experiment was conducted using an average cross-sectional water flow velocity of 48 to 137 cm·s-1, and using masu salmon fingerlings with a total length of between 4.4 and 8.8 cm (from 3.7 to 7.5 cm in the body length). Movement of tail beats were recorded during the swimming experiment using a high-speed camera. The results showed that the ratio of the amplitude of tail beats to the total length of the masu salmon fingerling was constant, even with an increase in frequency or swimming speed, and its value was 0.12. Masu salmon fingerlings swam with a tail beat frequency of 20.8 to 39.1 times per second, and a positive correlation was found between the swimming speed and the frequency even in the high frequency region. This allowed us to obtain an experimental formula defining the relationship between swimming speed and the frequency of tail beats.