This month's Atlantic includes a dispatch about an economic solution to poaching:

Harvesting big males might be sustainable, says Craig Packer, who studies lion ecology in Tanzania, but only at a rate that would yield far less in trophy fees—one lion per 1,000 square kilometers in rich habitat. Hunters in Tanzania take up to 10 times that number, shooting their way down the age cohorts.... A male lion needs six years to establish himself in a pride and rear a new generation.

Tourists would no doubt be horrified by the notion that trophy fees from hunters are one reason lions, leopards, and other predators are still out there for them to admire. But they themselves are guilty of indulging in a double standard. They object strenuously to any hint of hunting—and then, said one baffled tourism executive, “they tuck into a gemsbok steak that evening, without a pause.” One alternative that WWF hopes to test is getting tourists to behave like hunters and pay a sort of trophy-photography fee—say, an extra $10 for each sighting—to go into a special fund for lion conservation.

I would prefer, of course, that people shoot lions with Canons rather than guns.