过去探测鱼群主要是用观察的方法,看到海上出现鸟群或海上某些波涛汹涌,就有鱼群出现。现在在探测鲔鱼方面有了进展。鲔鱼经常出现在上层海区,大约在10多米的深处。使用探鱼仪对捕捞起一定作用,但缺少海水表面的信号,必须在渔船垂直地从鱼群上通过才能发现鱼群。因此有很多的拖网渔船在无鱼地区空开,而在离船几米的水深处却隐藏着 In the past, the main method of detecting fish was by observation. When birds or fishes were seen at sea, some fish appeared. Progress has now been made in detecting catfish. Catfish often appear in the upper sea, about 10 meters deep. The use of fish finders plays a role in catching fish, but the lack of signals on the surface of the sea water can only be found by passing the fish vertically across the fish. As a result, many trawlers have no space to open in the area without fish and are hidden in the depths of a few meters from the ship