Carp suck.
But I think it is related to turbulance caused by large schools of fish stirring up deeper, warm water and thinning the ice above. An underwater spring can do the same thing- or a bit of a drainage channel off a nearby hill, along the shore (ask me how I know this, too- Arctic experience.- but I have a fast throttle thumb!)
Best to stay off shore a bit. On fresh water, especially.
Last edited by las; 11/14/19.