Hunting is very popular, and you can even get people to hunt your pigs for you for free. Unless you really have a very high kill rate, all you're doing is educating pigs which locations to avoid, and in effect you're just scattering them to your neighbor's property or to other parts of your property depending on the size. You're not really doing much to control the population. Remember, you've got up eliminate 66% of the population annually just to keep the population in check.