Would a Captcha field counter spam when making a topic? I know a lot of it is human spam, but could it work in any sense?

There has seemed to be more spam recently, I've removed about 5 or 6 in the last couple days. I wonder if it has something to do with the holiday season; spam picked up on a forum I run within the last 2 weeks or so.

P2L has a Captcha field before registering so no I don't feel it would be of much use, we get less spam these days than what we did a year ago and it would become extremely annoying to have to type it everytime we posted.