You know it depends upon their reason for being anti hunting, if they are vegans ask them why they have canine teeth? If they are not vegans then tell them you feel guilty for hiring assasins to kill their meat for you and prefer to kill your food for your self. Ask them how does it feel to be an assasin?

You really need to do a lot of reading to be able to answer peoples questions. As JagMagMan stated hunters/outdoorsman have done more for preserving wild life than all other anti hunting groups combined. If these people use wildlife preserves, national forest, state or federal parks explain to them who finances the majority of them.