Duck mines

Every one knows those big old ocean mines from war movies with the spikes. That's the problem, people see them comming and avoid them, or blow them up. Submerged mines can be cut lose so they float to the surface, or exploded from a distance. magnetic mines will probably be found if they are suspected and searched for. My idea is to make mine that can hide in plane sight, a waterfowl mimicing detonator (WMD) The WMD would resemble a decoy duck, or whatever local waterfowl was least likely to arouse suspicion. A small sound chip can be included to make calls at random intervals. The WMD could be tethered to a nylon line with a contact detonator. Or remote controled/detonated by radio or cable. Or even just dropped around free floating if the current is slow. The WMD might be small, but quite enough against small river patrol craft.