The characteristics of current velocity near the sea bottom around fish-cultivated ground and the variation of turbidity related to its velocity were examined. Current velocity near the sea bottom below fish-cultivated cages was relatively faster than that of other stations. This result seemed to be caused by the mechanism of hydrodynamics. The power spectral density of current velocity near the sea bottom and of turbidity had peaks of 0.0362 and 0.0725cycle/min and the periodicities are 28 and 14min, which corresponded to the periodic components of seiche in Uragami Bay. It was obvious that the variation of turbidity near the sea bottom around fish-cultivated ground was influenced by the short periodic component in seiche.