Author(s): Guangning Li; Shuangke Sun; Haitao Liu; Tiegang Zheng
Keywords: Migration behaviors; Lateral-line system; Vertical slot fishway; Recirculation zone; Velocity gradient
Abstract: The lateral-line system is a key component of fish perception system, but the role of lateral-line system in the fish migration behavior is not clear. In this paper, through the fish passing experiment, we obtained the migration behaviors of Grass carp (living in steady water) and Schizothorax prenanti (living in rapid stream) in vertical slot fishway pools. We found that the lateral-line system of both the two kind fishes have the ability to feel the absolute flow velocity above a certain value, and they can actively choose the position with low flow velocity. A proportion of Grass carp tend to pause at the location lack of velocity variation, and some Grass carp shown poor orientation in the recirculation zone. But the Schizothorax prenanti has no behaviors like that at all. It can be explained as that the lateral-line system of Grass carp has more superficial neuromast (SNM), which is more sensitive to the absolute velocity value, but insensitive to the velocity gradient. When the gradient of velocity is small, Grass carp cannot distinguish the velocity gradient. Grass carp can feel the rotational flow velocity in the recirculation zone, resulting in milling behavior. The lateral-line system of Schizothorax prenanti has more canal neuromast (CNM), which is more sensitive to the velocity gradient and less sensitive to flow velocity than Grass carp. Schizothorax prenanti can find swimming direction where Grass carp paused, and it cannot feel the rotating velocity in the recirculation zone, and it will not do the milling behavior.