丘陵地小河川における簡易魚道を用いた ホトケドジョウの遡上経路の再生への試み

Abstract

From 2007 to 2009, an endangered species of loach, Lefua echigonia, was collected at 68 out of 192 investigation sites in the streams in and around the EXPO 2005 Aichi Commemorative Park, central Honshu, Japan. Distribution pattern of the loach suggests that the migration of the loaches in this region must beprevented by 3 weirs of which the one was built across a stream in the EXPO Park. To mitigate this impact, portable fishways were tested in laboratory experiments and in situ experiments on the weir in the EXPO Park. In the laboratory experiment, the loaches ascended the fishways in many cases with the water flow of 50-550 mL/s, at the slope of 0.6-20°, and at the water temperature of 10-26􀎥. The loaches tend to hesitate ascending the fishways in the low temperature of water. In situ experiment in the EXPO Park, the loach seldom ascended the portable fishway, only at the slope of 4.4°.