Fig. 3. A swaying acceleration profile of a chum salmon swimming at a flow rate of 0.7 m s^–1 in a chamber. Video recordings were used to confirm that each sharp peak in acceleration synchronized with one tail beat. When the salmon beat its caudal fin to the left, the acceleration reached a positive maximum value and vice versa. For the peaks indicated, the amplitude of the peak (H) was greater than 1.0 m s^–2, and bottom–peak–bottom duration (T) was less than 1 s. These values were recorded and converted to tailbeat frequency.