Characterization of Siberian sturgeon (Acipenser baerii, Brandt 1869) sperm obtained out of season

The aim of this study was to characterize and compare the basic parameters of Siberian sturgeon (Acipenser baerii) milt and sperm motility of semen collected in December and April. In addition, the suitability of semen was determined for short-term storage and cryopreservation. Sperm collected in December was characterized by an unusually high percentage of spontaneous motility (40%) as opposed to semen collected in April (5%). Sperm from December was characterized by a low sperm concentration (0.19x10(9)ml(-1)), high protein concentration (0.86mg ml(-1)) and pH (8.7) of seminal plasma in comparison with sperm obtained in April (1.21; 0.38; 8.41, respectively). Semen obtained in December could be successfully short-term stored and cryopreserved. The fertilizing ability of cryopreserved sperm from December determined by the hatching rate was similar to that from April (22% and 29%, respectively). The results suggest that the quality of semen parameters stabilizes in sturgeons during reproductive maturity. Methods of short- and long-term storage (cryopreservation) of sperm obtained in December can be implemented for the artificial reproduction of Siberian sturgeon.