Summary：Swimming performance is one of the most important capacities for fish to cope with the harsh conditions in natural ecosystems and thus determines fitness of hatchery-reared fishes for stocking in the wild. Poor swimming capabilities of hatchery-reared fishes, including sturgeons, may be linked to the fact that the flow regimes in conventional culturing tanks are very often static and with very low currents, obviously differing from the natural environment. The objectives of the present studies were to: (i) learn about the swimming performance of the Dabry’s sturgeon Acipenser dabryanus, one of the critically endangered species restricted to the Yangtze River, China; (ii) ascertain if it is possible to improve the swimming capacity of Dabry’s sturgeon (DS) by changing the current flow regime in conventional culturing tanks; (iii) determine the potential effects of such an environmental enrichment practice on the growth and survival of DS. Long-term culturing protocols with two culturing stages were conducted in a conventional tank with static water (Control, CT) as well as in a current-enriched tank with a step-controlled water velocity (CET). Results showed after the first culturing stage, which began with 500 15-day-old post-hatch (dph) DS and ended with 40 dph DS, that the survival rates in CT (91.6%) were higher than that in the CET (84.4%). Total length, fork length and weight of DS in CET (n = 30) were higher than in CT (n = 30), but with no significant differences (P > 0.05). The Ucrit (13.2 2.9 cm s 1, or 2.19 0.48 FL s 1, n = 30) of the 40 dph DS in CET were significantly higher (10.2 3.5 cm s 1, or 1.70 0.59 FL s 1, n = 30) than in CT (P < 0.05) and the swimming endurance (101.6 38.2 min, n = 15) of the 40 dph DS in CET at a velocity of 20 cm s 1 (representing 1.5-2.0 times Ucrit of 40 dph DS) is obviously longer (72.4 38.2 min, n = 15) than in CT. The second culturing stage followed with 200 individuals of 40 dph DS coming from the first stage and ended with 80 dph DS. The survival rates during the second stage and the final growth parameters of  80 dph DS in CT and CET were not obviously different from each other (P > 0.05), whereas the Ucrit (48.5 6.9 cm s 1, or 3.25 0.46 FL s 1, n = 20) of the 80 dph DS in CET were also obviously higher (35.9 8.5 cm s 1, or 2.41 0.58 FL s 1, n = 20) in CT (P < 0.05). The results suggest a possible conservation culturing practice to improve the swimming capabilities of DS and will be foreseeably beneficial for hatchery-reared DS fitness when stocked in the wild, and  will contribute to the effectiveness of future DS rehabilitation programmes.

H. Du, Q.-W. Wei , X. Xie , L.-L. Shi, J.-M. Wu, X.-M. Qiao, Z. G. Liu. Improving swimming capacity of juvenile Dabry’s sturgeon, (Acipenser dabryanus Dumeril, 1869) in current-enriched culture tanks. Journal of Applied Ichthyology, 2014, 30: 1445-1450.