Effects of age and size on critical swimming speed of juvenile Chinese sturgeon Acipenser sinensis at seasonal temperatures.

Changes in the critical swimming speed (Ucrit, cm s−1) with ontogeny of 2·5–12·5 month-old juvenile anadromous Chinese sturgeon Acipenser sinesis were measured in a modified Blazka-type swimming tunnel. The absolute Ucrit increased with length, mass and age; the relative U′crit (body lengths, s−1), however, decreased. Juvenile A. sinesis did not display a parr–smolt transformation at the length or age threshold to tolerate full-strength seawater.