Hey, /b/, I've got a little problem. The local lake by my house has a turtle problem. There are so many freshwater turtles it's not even funny. So the city encourages catching them. However, when you catch them, the hooks are near-impossible to get out (those little fuckers bite hard). What's the most humane way to kill a turtle on the spot?

TL;DR: What's the easiest, most humane way to kill freshwater turtles?