Investigating the Effects of Different LED Wavelengths on Aggregation and Swimming Behavior of Chub Mackerel (Scomber japonicus)

Efficient fish aggregation systems are essential for catching chub mackerel ( Scomber japonicus ), which is a major target of purse seine fisheries in South Korea. To aid the development of such systems, this study used a Dual frequency IDentification SONar acoustic camera and a visual camera to investigate the effects of light emission diode (LED) aggregation systems of different light wavelengths on the frequency of occurrence and swimming behavior of chub mackerel. The experiment was performed using 50 individuals in a circular tank (diameter, 6.0 m × height, 1.5 m). The LED aggregation systems emitted blue light (454 nm), white light (545 nm + 560 nm), yellow light (596 nm), and red light (634 nm). At night, initial swimming speed increased in response to the four LED systems, and stabilized over time. Frequency of occurrence was highest under blue light, followed by yellow light, white light, and red light, in this order, and, according to wavelength at daytime and at nighttime, it was highest under blue light. The swimming speed of the mackerel school showed an increasing trend over time for all LED aggregation systems, and, for blue light, there was a large, rapid increase in swimming speed.