Canal report 6/23 with a question

[WLaMarr]

Fished from slack (5 pm) to slack (11 pm) last night and then some in four different spots on the canal with one schoolie to show for it. However, I wanted ask a question. I was fishing eels around 1 am and got a real strong hit. Then the line went kind of dead. I picked up the slack, and sure enough, whatever it was, was still there. As I raised my rod I felt three strong successive tugs (a head shake maybe?) and then, POP, my line broke at what seemed to be right above the hook. I reeled my line back in and took a good look at the line in my flashlight. It wasn't "pigtailed" and did not appear to be frayed, stretched or kinked in any way. Just a very clean cut in the line. Any ideas as to what happened? My first thought was a big blue, but don't they usually hit eels at the tail, not the head? Maybe it got sliced up on a rock?

Anyway, my question is "How many of you 'always' use leaders in the canal?" If you do, what kind, test, length, etc... do you use?

Thanks.