EFFECTS OF INTERMITTENT LIGHT FLASHING FREQUENCY AND ILLUMINANCE CHANGE ON EVASION CHARACTERISTICS OF OPSARIICHTHYS PLATYPUS

Fish such as salmon and trout that have been released into the water intake of dams and weirs have strayed, and the actual amount of fish consumption has been a problem since long ago. As a prevention of fish from straying, transmitted light, foam film, electirc current, obstacle were used to control the behavior of fish. The reesearch of evasion behavior using continuous light has been done. However, the research of evasion behavior using intermittent light flashing frequency and illuminance change has not been done. In this study, the evasion behavior of Opsariichtyis platypus were compared with the change of intermittent light flashing frequency and illuminance change. As a result, it was found that the rate of entering into bright area decreased with an increase of light flashing frequency. Also, it was found that as the light flashing frequency increased, the aveage swimming speed increased and the staying rate decreased.