Ransoming unskilled captives en masse is fairly easy by ctrl-clicking at the stockade,
I'd like to be able to ransom those slop suckers too, but the game doesn't allow you to. What I think you mean is that you can ransom SKILLED captives at the stockade. And no, there's really no easy way to ransom off the wealthies other than using the almanac. You can try the entertaiment buildings and/or hotels; they're usually hanging out in those places.
One other way to get rid of pirates is to send the ones you don't like on a small ship in a dangerous part of the ocean. They won't come back alive.
Or, if you have my luck, send 'em all on a big ship in dangerous waters. Same effect, bigger numbers, more teeth gnashing.