To investigate the mechanism of attracting large-sized neon flying squid (>30cm mantle length), Ommastrephes bartrami, to fishing lights, experimental hand and machine jigging with fishing lights were carried out in the North Pacific Ocean. The eyes of captured squid were examined histologically for retinal adaptation. Squid were caught at different depths (20, 50, 100, 150, 200m) using onboard fishing lights at night and in the daytime with underwater fishing lights placed 180m deep. Their retinae were all dark-adapted when captured during the daytime and at night. Since squid were caught at nighttime at greater than 100m depths using jigs with 300kW fishing lights, it is supposed that the powerful fishing lights have deepened the distribution of squid whereas driftnets captured squid at depths of 7-10m when set at night.
