In my opinion, there is no excuse for poaching. anyone i see on my permission either lost or otherwise i approach, those who are genuinly lost i dont mind too much, although very annoying. but those who poach is another mater, i had one guy driving around a wheat feild with his dogs running around, and when i approached him he became very aggressive, partly due i was about to shoot his dogs as they were running at me and my dog about to latch on.
the only way to stop it is either treat the problem as you would anyother vermin control, but as the law doesnt share our same veiw, maybe invest