Spam in my comments

Hi, Just wondering if someone could help me out with this issue. I currently have it set up that anyone who tries to comment on one of my posts must have it moderated by me before it appears. The problem is that I’m getting anywhere between 30-60 moderation requests per day for comments that are nothing but spam messages with a lot of links in them. Could anyone tell me if it is possible to get rid of these from coming in so that only normal posts appear?

Cheers…