With esperience, and with inproved apparatus,it is now possible not only locating a shoal but to tell if it is herring cool or other well-known fish, by the pattern of its echo.

• 根据经验以及先进的设备，现在不仅能判断鱼群的位置，还可以通过回声的种类来判断是青鱼还是其他著名鱼种。