Journal of the Japan Society of Erosion Control Engineering, Vol.56,No.6,2004

The Swimming behavior of the stream‐dwelling masu salmon relevant to the type of inner structure in fishways on Sabo facilities

Tetsuya KUBOTA, Tomoe IKI, Masayuki TANIGUCHI

Abstract

Stream type fishways are more desirable for various species than classic pool type fish ladder. However, there exist many old type fishways that have been already built into Sabo facilities. They need certain improvement in the structure and discharge control to maintain fish passage conditions. In our former study, the desirable minimum pool length of fishway and critical nap velocity were studied. Hence, in this study, fish behavior about masu salmon with various discharges and step heights comparing with two inner structure, that is, "slope separation wall type" or "step separation wall type" concerning with pool separations were studied by experiments to extract the versatile information for the improvement of fishways already built. Eventually, the critical relationship for the swimming behavior between pool depth and drop height was obtained, and it was also found the difference of fish behavior among inner structure types that is meaningful in the assessment of appropriate structures.

Key words:fishway, masu salmon, sabo facility

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