Fig. 8. Body outlines of a dead trout towed behind the cylinder (A), a live trout Kármán gaiting behind the cylinder (B) and a live trout swimming in uniform flow at 3.5 L s^–1 (C). Within each experimental treatment, body outlines have been displaced upstream at evenly spaced intervals to facilitate visualization of kinematics. Similar to a live trout Kármán gaiting, a dead trout towed in the wake of a cylinder oscillates laterally with high amplitude and has a tail-beat frequency similar to the expected vortex shedding frequency. The body wavelength is also longer than the expected wake wavelength, confirming that live fish can synchronize to the vortex street in a largely passive manner. Dead and live trout behind the cylinder adopt the same mean head angle. However, live trout head angles have a wider range of values and a higher variance, indicating a larger change in head angle during the Kármán gait compared with dead trout.