How to get rid of gophers?

I have a really bad gopher problem but the last thing I want to do is kill them. I've seen their heads popping out from their holes. I've tried putting a hose in their holes. Destroying their homes. Even those ultrasound things. Any other suggestions to get rid of gophers? I know I have snakes and owls in my area? Is there any way to attract more of them? I also heard one can use moth balls to irritate the nose of raccoons and possums, will they also irritate the noses of gophers?