We used to harpoon the big ones we wanted to keep, cleat them off, get them bleeding good, and then once they settled down we'd run a line around their tail like a noose and then shove it through the mouth with the hook release. Once you drag them aboard, pull the rope tight and tie it off it so bends their head back toward the tail so they can't flop around or do any damage. They just sit there like a big rocking chair.

Little chickens we'd gaff, rope off, and hang over the edge. No problemo.

We landed halibut well over 200 lbs and never used a gun. My employer's policy was not to allow guns in the boats. Smart policy if you ask me. I really don't think they are necessary, and the consequences of a screw up are obvious. I've seen lots of idiots shooting small halibut they could have handled easily without all of the drama.