The effectiveness of a modified Ice Harbor-type fishway on the Geum River in South Korea was investigated for native freshwater fishes, using trap and passive integrated transponder (PIT) telemetry. The traps were installed at the exit part of the fishway, and fish use was monitored monthly from June to October 2012. Fishes were caught by a cast net and a fyke net at the lower part of the Gongju weir for PIT tagging. The tagged fishes were released downstream of the fishway. Three antenna lines (entrance, middle, and exit) were installed along the 70-m stretch of the fishway to investigate fish passage. A total of 1114 individuals, classified into 21 species and 4 families, were collected by the traps, with fishes of family Cyprinidae being dominant. The total length (TL) of fishes collected by the traps ranged from 40 mm (Rhinogobius brunneus) to 504 mm (Erythroculter erythropterus), with a mean of 161.3 +/- A 82.3 mm. The overall attraction and passing rate of the fishway were 15.3 and 43.2 %, respectively. TL had no effect on the attraction and passing rate of tagged fishes. Even though some Cyprinidae species required > 6 h to move through the fishway, most fishes passed through within 6 h. Most fish detections occurred when the water level in the fishway exceeded the management level. To our knowledge, this study is the first to investigate the use of a fishway by Korean freshwater fishes, demonstrating the high use of a modified Ice Harbor-type fishway. To confirm whether this type of fishway is ideal for Korean freshwater fishes, other fishways must be evaluated. Such research would contribute towards the development of optimal fishways for this location and towards the establishment of operational strategies that facilitate the passage of more fishes.
