Kinematics of lake sturgeon, Acipenser fulvescens, at cruising speeds

Abstract

Lake sturgeon, 15.7 cm in total length, have a 2-min critical swimming speed of 38.6 ± 4.2 cm∙s−1 (2.45 body lengths∙s−1) at 15 °C. Tail beat frequency (ƒ, Hz), amplitude (a, cm), and propulsive wavelength (λ, cm) increased linearly with swimming speed (U, cm∙s−1), according to the following equations: ƒ = 1.67 + 0.07 U, a = 3.2 + 0.020 U, and λ = 11.0 + 0.039 U. Tail depth and the cosine of the angle of the tail with the axis of motion were independent of swimming speed with mean values of 1.96 ± 0.08 cm and 0.7 ± 0.08, respectively. Swimming kinematics were generally similar to those of teleosts and anuran larvae, implying that body and caudal fin propulsive movements are conservative among actinopterygians and tetrapods. Swimming patterns did not provide for interactions between median fins that are considered to be important to shark swimming. The thrust generated by swimming sturgeon averages 82% that of trout of similar size, although the surface area of sturgeon is substantially lower. Therefore, drag per unit area of sturgeon is 3.5 times that of other actinopterygians, presumably because of the presence of scutes.