Good advice from Rusty. I've killed a few with a catch pole. However, we did manage to keep two alive in one day, killed one the same day, using a homemade catch pole. Had a guy buying them from us in 1983 and paying $350 for them alive, which was much better than $200 dead. Put them in heavy wool sacks ( like a gunny sack only much thicker). Once cat had worked a hole through the sack by morning and had his entire paw outside. I think he was about to make a jail break.
I prefer to release them with a .22 short anymore. Had enough of that catch and release stuff. That's for TV fishermen.