Ventilation frequency in juvenile beluga sturgeon Huso huso L. exposed to clay turbidity

Abstract

A 2-factorial experiment was conducted to investigate the effect of clay turbidity on ventilation frequency (VF) in juvenile beluga sturgeon Huso huso. Ninety fish (initial mean weight 27.2 ± 0.1 g) were exposed to six levels of turbidity (0.0, 2.5, 5.0, 10.0, 20.0 and 40.0 g clay/l) for three min. Then, the fish were gently transferred to a recovery tank and monitored to record the VF for 3 min. Results indicated that clay turbidity significantly affected the VF of the fish. The highest VF was observed in the first minute after the exposure. VF increased with increasing clay turbidity levels. In addition, the obtained results showed that VF of the beluga decreased through the time. Based on the result, it can be concluded that the beluga has the ability to adapt to clay turbidity in a short time; although they had an acute stress at first.