Summer Patterns and Diel Variations of Fish Movements Using Fish Trap Sampling Technique in the Juksan Weir

Abstract The objective of this study was to evaluate seasonal patterns and diel variations of fishmovements in the Juksan Weir which was constructed in 2010 at the down-stream of Yeongsan-River watershed. For this study, we monitored day-and-night movement(24 Hr cycle) andseasonal fish migration(June _August) patterns in 2011 along with species compositions andabundances depending on the locations of the traps within the fishway. Total number of speciessampled was 14 and the total number of individuals was 1,263 with only the size-fractions(astotal length) of the fish < 20 cm during the study. Seasonal analysis of fish movement in the fishway showed that highest frequency in the movement occurred in June - July, which is closelyassociated with a spawning peak season. The most dominant species using the fishway was Squalidus chankaensis tsuchigae , and this species turned out to be 26.9% of the total in the use rateof fishway. Daily monitoring of fish movements showed that most frequent movementsoccurred between 18:00 PM and 21:00 PM when the fish have a feeding time generally. Themigratory fish were not found in the fishway during the study. Mean current velocity duringthe study 0.42 ‚0.02 ms