@Team9nine Yeah it blew my mind last year when they did it even more frequently, as I'd always heard winter fishing is slow, the fish are sluggish, etc.
It slows way down once they start spawning, but then the Shad Spawn kicks in and you get that whole deal around April. They do it on the "hi activity" days year-round, but nothing like what they do in the winter. Fall has a ton of it, but I've found for whatever reason the size class fish are much smaller predating on them.
I've spent as much time trying to learn Gizzard and Threadfin Shad as Bass since fishing this lake, but they're as hard to predict and understand as Bass for me. For example Feb 8-9 last year I had 40-50 fish days in that same area as today, and the amount of Threadfins were equally as staggering, yet they were in 20-25fow carpeted up for hundreds of yards with the spaghetti right above them, and I was using a Damiki Axe Blade 1oz tail spinner to catch them in about 15-20ft.
Today they were in 8-10fow exploding upwards at groups of thousands yet spaced out balls of Threadfins sunning on the surface.
Too much info I'm sure, but those Shad fascinate the heck out of me.
Agreed on the second part, and hopefully it's something improvable and with work I'll grow in that area.
As far as the first part, I think there's lots of logic in the fact that you can have too much of the real thing and at some point it's impossible to compete with the real thing. One thing I've found is that these fish seemed to be keyed in more on size than any other factor of the real prey. I get the best results matching the size first and then trying other things.
Usually a Vision 110jr is kryptonite for them in the Fall, and in the Winter an A-Rig. I've had times where the Flashback Mini with the Armor Shad destroys them as well. They usually have a magic button, but some days you just can't really find the perfect one, or even one at all. I had a couple days IIrc last winter where they wouldn't eat anything, not a single fish.