Actually you're pretty correct about individual enforcement of DFG rules coming by way of private action. I think it's called a Private Attorney General Action, and its where non deputized citizen can bring suit against someone who violates some statute. Its allowed after you get an "OK" from the DA's/ AG's office validating the cause of action and checking out the evidentiary matters. It's mostly used in conjunction with fair debt collection violations but that'd be pretty kickass if someone did one under DFG. You could even pick up attorney's fees I think.

As far as warnings go, I've tried that one a couple times and it never goes over well at all. I remember swimbait posted last spring where he described how he told some dude not to snag largemouth with a kastmaster yet the guy still strung his catch. That's shameful, but is it preventable on the spot? tough one.