THE EFFECT OF GRAVEL DEPOSIT IN A POOL-AND-WEIR-FISHWAY ON THE SWIMMING BEHAVIOR OF TRIBOLODON HAKONENSIS

Abstract

 In this study, the purposes are to make clear the influence on the swimming behavior of Toriborodon hakonensis with gravel deposit in a pool-and-weir-fishway. Therefore, the experiments were done. The experiments carried out the hydraulic experiments and observed the movement of real fish. Especially, the attentions are focus on the staying behavior of Toriborodon hakonensis. As the results, the flow showed the plunging flow in spite of the presence or absence of gravel deposit. However, the plunging flow area decreased to approximately 50 ~ 80% when gravel deposited. The flow formed the rotation of positive and negative, Toriborodon hakonensis were facing for upstream and downstream. Moreover, the staying time of Toriborodon hakonensis in the pool was increased and the run up ratio was decreased. Additionally, Toriborodon hakonensis stayed on the gravel whose velocity was 2BL (cm/s) and y was 10 ~ 15 (N/m²).