Late Fall River crappies

[Big Jeff]

My question is what do the crappies do when the water cools down, I found them two weeks ago but I think things have changed quite a bit(water temp/winter weather). I found them between 15-30ft of water but all stacked into about 2 different 50 yard streches some where even in less than 15 and a few where in 40 right off the bottom. Some came on flu flus under slip bobbers others on a lindy set up 1.5 - 2 ft long. Looking for advice on where or how they may have moved with the change in conditions and how to fish them.

Thanks