Burton, I was at the same location you speak of on Thursday pitching a jig on the shoreline, hooked into something huge, and turned out to be a large carp, i had seen a few earlier but had no idea they would hit on a common crappie jig, obviously i was wrong, same thing after keeping it on for a while with no chance of landing it the line finally snapped. I saw several afterward and I'm pretty sure this is what snapped your line, but you never know i could be wrong. Water is warming so it should pick up soon...