Study on flow characteristics and ascending fishes in Ice-Harbor type fishway of Akaishi-the number 2 headworks on the Akaishi River [Aomori, Japan]
2001
Izumi, M. (Hirosaki Univ., Aomori (Japan). Faculty of Agriculture and Life Science) | Takaya, D. | Kudo, A. | Azuma, N.
Experimental study on the relation between the ascent of fish and the hydraulic characteristics was carried out in the ice-harbor type fishway (width; 2.6m. drop; 0.15m. slope; 1:20. length; 71.0m) of Akaishi the number 2 headworks on the Akaishi River, one of the B-class rivers in Aomori Prefecture. Thirteen fish species, mainly consisting of Plecoglossus altivelis (Ayu) (72%), Tribolodon hakonensis (Ugui) (15%). Rhinogobius brunneus (Yoshinobori sp.) (7%). Chaenogobius sp. (Ukigori sp.) (3%) and Cottus hilgendorfi (Kajika) (2%). were confirmed to ascend the fishway. The daily time zone in which ascending was most frequent was generally from afternoon to just after sunset (about 8 p.m.), though it differed between examination days. On the other hand, the swimming fish were confirmed to ascend through the orifices, from which the orifices were confirmed as functioning as passage facilities. The hydraulic characteristics in the fishway were clarified from the three-dimensional composite vector distribution of flow-velocity and the two-dimensional composite vector distribution of flow-velocity each within the pools in the fishway.
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