Let them legally get out of their sweet little trees in one place for a month or two, then round them up, stick em on a plane to a country that know how to deal with them. I have a recollection that the Taliban were actually very good at the job the DEA try and do in the US?
Those that aren't dumb enough to fall for it, are probably intelligent enough to get a job of sorts and pay for the next hit at a legalised price with duty (lucky Mr Darling).
Do the same thing every year or two and ...... ever been to Norway/Canada during a seal cull? It ensures balance is maintained in the food chain. Not nice but necessary.