Results of comparative cultivation of kaluga, amur sturgeon and reciprocal hybrids between them with using of various technologies
Pure species obtained from the breeding stocks of the Pacific branch of VNIRO (Russian Res. Inst. of Fisheries and Oceanography), as kaluga Huso dauricus and amur sturgeon Acipenser schrenckii , as well as reciprocal hybrids between them K×AO and AO×K, were grown in parallel in tanks with recirculation aquaculture system (at fish farm near Moscow) and in net cages with heated water (at fish farm in Luchegorsk, not far from Vladivostok) for three years, 2018-2020. Survival, growth rate, feed costs, and cultivation density were determined for the experimental groups of fish on the main biological stages (embryos, larvae, fry, juveniles). Certain differences in survival and growth rate were found between the pure species and hybrids cultivated in different conditions. In the embryonic period, both survival and growth rate were higher for fish in cages, possibly because of long transportation of eggs to Moscow. For other stages, survival of K×AO was the highest in tanks, with exception of one-year-old fish, whereas survival of kaluga was the lowest at this farm, with exceptions of early juveniles (weight 2-3 g) and two-year-old fish. For Moscow farm, survival in tanks was: kaluga 9.3 %, cross K×AO 21.7 %, cross AO×K 26.8 %, amur sturgeon 28.9 %. For Luchegorsk farm, survival in cages was: kaluga 10.5 %, cross K×AO 11.5 %, amur sturgeon 19.5 %, cross AO×K 21.2 %. The effect of heterosis was observed for survival in cages, but not in tanks, where the rates for hybrids were between the rates for their parental species. At the third year of cultivation, the greatest weight increments were observed for kaluga and K×AO in cages and for kaluga and AO×K in tanks. By the autumn of the third year, the average weight in tanks exceeded this one in cages in 2.0 times for AO×K and amur sturgeon, in 2.5 times for kaluga, and in 3.0 times for K×AO. Kaluga and hybrid AO×K had the best growth rate in cages at Luchegorsk farm, but Kaluga and hybrid K×AO had the highest growth in tanks at Moscow farm. The integral score accounting the main indicators of fish breeding, as body weight of fingerlings, survival and feed cost, for the cage growing was the best for hybrid AO×K and for the tank growing - for hybrid K×AO. The comparative experiment confirms technological advantages of the sturgeons breeding in tanks. Due to warmer conditions of the growing, commercial product of kaluga and cross K×AO can be obtained by the middle of the second year of cultivation, and other species reach the commercial weight in the third year. In the case of cage breeding, kaluga and cross AO×K only reach the commercial weight in the third year of cultivation.