Oxygen consumption and swimming behavior of juvenile Siberian sturgeon Acipenser baerii during stepped velocity tests

Oxygen consumption rate (MO2) and critical swimming speed (Ucrit) of juvenile Siberian sturgeon Acipenser baerii were measured at 24°C using a step-wise velocity test in a flume-type respirometer. Swimming behavior was video-recorded before and after the swimming experiment in a respirometer and an open tank. The relationship between MO2 and swimming speed (U) can be accurately described by a power function. The Ucrit of A. baerii was found to be 2.28 ± 0.09 body lengths (BL) s-1 or 0.51 ± 0.05 m s-1. The standard metabolic rate was calculated to be 149.24 mg O2 kg-1 h-1, and measured maximum metabolic rate (MMR) was 385.04 mg O2 kg-1 h-1. This is a relatively low MMR, resulting in a low metabolic scope, and is consistent with the low Ucrit of juvenile sturgeon. Excess post-exercise oxygen consumption, measured over a 60 min recovery period, was 65.20 mg O2 kg-1. Therefore, A. baerii possess high fatigue recovery capability. Tail beat frequencies increased significantly with U, but there was very little change in tail beat amplitude, and results differed between respirometer and open tank observations. Our results provide data on the physiology and behavior of A. baerii and will help to support conservation of this important species