STUDY ON THE INFLUENCE OF WINTERING TEMPERATURE ON CERTAIN SEMEN CHARACTERISTICS IN STERLET (ACIPENSER RUTHENUS)

Sterlet (Acipenser ruthenus) is a species with seasonal reproduction, temperature being considered one of the most important key factors that ensures the seasonal reproductive cycle. The wintering temperature should be carefully controlled to prevent any adverse effects on reproduction. In many fish species, the wintering at high temperatures have a negative impact on reproduction success. The aim of this study is to evaluate the impact of wintering temperature on sterlet males by evaluating the quantity and quality of the semen collected from them during the breeding season. Two groups of males were overwintered at different temperatures, with minimums of 10 degrees C (G1) and 6 degrees C (G2), respectively. The semen collected from these males was analyzed, determining the volume of collected sperm, the concentration of spermatozoa and the number of spermatozoa, all of which were determined for two collections made at an interval of 2 hours. Gonadal measurements were also taken to determine if there were any differences between the two groups. The results showed that the volume of milt, sperm concentration, as well as gonad mass and the gonadosomatic index, did not differ significantly between the two groups. Thus, it can be concluded that wintering of sterlet males at temperatures no lower of 10 degrees C does not negatively influence the reproductive characteristics analyzed, showing only insignificant differences compared to males wintered at lower temperatures.