Current Status of Fishways in Domestic Agricultural Weirs and Effect of Functional Improvement

In this study, the effect of fishways as a connection passage for streams was investigated by improving their function installed in small-scale agricultural weirs. For this study, statistical data of the National Fishway Information System(NFIS) were analyzed, and the fish species and community similarity of 28 weirs that improved the function of fishway were investigated. Currently, 33,930 agricultural weirs have been installed in the streams and are operated for the purpose of supplying agricultural water. 5,582 fishways were installed on the weirs for the migration between upstream and downstream of fish and securing continuity in disconnected streams. However, the install rate fishways is only 16.5%, of which 67.3% have lost their function or need improvement. Accordingly, the renovation effect analysis was conducted on 28 fishways that improved their function. As a result of analyzing the fish community similarity which identifies the connection between upstream and downstream of the weir, there is a difference in similarity due to the different stabilization stages between habitat and environment, but overall, it is observed that the function of the fishways has been improved. Due to the active use by fish, the habitat increased to around 3 species on average, and the connection of streams improved by more than 10%. In addition, as a result of trap survey, the migration rates of Plecoglossus altivelis, a representative migratory fish, and Zacco platypus, a major dominant species in Korea’s streams, were high. The number of species or individuals increased at the more than 70% in tested fishways. For the continuous proper functioning, it is necessary to prevent the decrease of the fishway function, a passway of fish, caused by flow rate changes and sedimentation. Furthermore, it is required to enhance the fishway functions: education, culture, and experience as well as migration in order to create multiple values of fishway installed in weirs.