中层拖网是以中水层鱼类为捕捞对象,所以在捕鱼作业过程中必须时常把网位恰当地控制瞄准目标鱼群的所在位置。在以前的中层拖网渔法中,网位的控制主要是通过调节曳纲长度和船速度来实现,但现在的渔具控制实际上几乎都是依靠船长和渔捞长的经验和直觉来进行。关于中层拖网的研究并不多,尤其是在网位控制过程中拖网系统的动 Middle-level trawling is based on aquatic fishes for fishing, so in the course of fishing operations must often be properly controlled network aimed at the location of the target fish. In the previous middle-level trawling law, control of the net position was mainly achieved by adjusting the length of the dragline and the speed of the ship, but almost all current gear control is actually based on the experience and intuition of captains and fishing vessels. There are not many studies on the mid-level trawling, especially the trawling system during the control of the network