This is a great site with eleven ways to manage snails in a permaculture fashion.  My first choice is number one, if you have too many snails, you don’t have enough ducks.  Ducks will keep your garden clear of snails and slugs and also do very little damage to your garden.

http://practicalpermaculture.com/2011/07/eleven-ways-to-get-rid-of-slugs-and-snails/