Abstract
During squid jigging operations, the hauling velocity of the jigs changes periodically with the up-and-down motion. We observed 62 Japanese flying squid, Todarodes pacificus, in a large experimental tank to clarify the relationship between the up-and-down motion of a jig and jig capturing behavior of the squid. When a jig was put into the tank, the squid recognized the jig, turned toward it, and approached it to capture it. The squid reacted to the jig when it was falling, but none reacted to the ascending jig. When the squid is in a hovering posture, its visual axes are considered to be directed forward. Consequently, the squid attacked the falling jig as it is easier to see the jig while it is falling down from above and coming into view. Over 10 minutes, we observed 52 approaches, of which only 3 were successful. We believe that in many cases the squid gave up their approach because the jig moved away too quickly in the time between jig recognition and capture. In cases of successful capture, the squid captured the jig when its velocity had slowed. We conclude that the squid is more likely to be successful by performing capturing behavior when the velocity of the jig is decreasing.
https://ror.org/02e16g702 
