Fig. 10. Schematic illustration of laterally directed dorsal fin force (large blue arrow) generated during steady swimming at 0.5 and 1.0 L s^–1 by rainbow trout, the roll and yaw torques (curved blue arrows) induced by this dorsal fin moment, and the hypothesized counteracting torques (red arrows) produced by the pectoral and anal fins to achieve a moment balance during steady locomotion. Asymmetrical movement of the caudal fin and oscillation of the pelvic fins could also assist in generating compensatory roll and yaw moments. Although the paired fins are not recruited continuously by trout during steady swimming (Drucker and Lauder, 2003), intermittent excursions of these propulsors may serve to correct moment imbalances. Steady swimming by trout involves the active use of multiple fins to maintain body stability in the face of environmental perturbations. CM, center of mass of the body.