Critical swimming speed associated with body shape of Chinese sturgeon Acipenser sinensis under different rearing conditions

It was hypothesized that differences of body shape between pond-reared and tank-reared juvenile Chinese sturgeon Acipenser sinensis may influence their swimming ability, and thus may play an important role in their stocking into the native population. In this study, morphological characters and critical swimming speed (Ucrit) of the pond-reared (body weight, BW = 1426.0 ± 53.8 g, n = 6) and tank-reared (BW = 1201.6 ± 91.4 g, n = 6) size-matched juvenile Chinese sturgeon were measured and compared. The Ucrit of pond-reared sturgeon was 81.3 ± 3.2 cm/s (relative critical swimming speed, Ucrit’ = 1.32 ± 0.04 SL/s), which was not significantly higher (P > 0.05) than that of the tank-reared cohort (Ucrit = 76.2 ± 1.9 cm/s, Ucrit’ = 1.40 ± 0.03 SL/s). Rearing condition had some significant effects on 12 of morphological characters of the Chinese sturgeon at their early life stage (P < 0.05), but there was only a tendency to be difference between the body shape variations as defined by PC1 (body and caudal length, body depth and caudal filament length) from the principal component analysis (PCA) with 12 size-adjusted morphological characters of the two different cohorts (P = 0.051). There was a significant negative relationship between Lg (Ucrit) (y) and PC1 (x), which could be described by the equation as follows: y = 1.897 - 0.002 x (r2 = 0.372, P = 0.035). These results indicated that rearing condition could not significantly influence the swimming ability associated with body shape of the juvenile Chinese sturgeon, but we should select streamline-bodied juveniles when releasing them into nature. Furthermore, the findings may be useful for a fish way and culvert design due to stringent regulatory requirement.