2021 Volume 77 Issue 2 Pages I_1411-I_1416
The purpose of this study is to verify the function of a removable stream fishway installed in the head construction of an urban river. Therefore, we carried out the experiments in the field where is Koedo River in Wako, Saitama Prefecture. In the experiments, it was used juvenile Ayu; Plecoglossus altivelis altivelis of body length 4.0 cm to 5.8 cm which number of fish is 100. As the results, approximately 8 % of juvenile Ayu run up to most upstream of fishway and approximately 24 % of juvenile Ayu to went upstream from the entrance of fishway, despite the short experiment time of 15 minutes. Therefore, it was confirmed that the removable stream fishway installed in this study. If the time is long, it is thought that juvenile Ayu can run up more. In addition, many swimming fish can be expected to use this fishway. Moreover, the fish collection situation was fair, because juvenile Ayu at 50 % of the probability were swimming toward the downstream entrance of the fishway. It is advisable to provide priming water and others to collect more fish, however it is considered to be strict in terms of conditions. Therefore, the expectation of fish collection can be improved by providing measures to prevent invasion suitable for this field.
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