Most of the smaller fish will be taken by predation. Smaller fish in poor condition at onset of cold may die from starvation related health issues if eats hard to come by. Some actually grow during winter, even in central Missouri. The Piedmont is a milder setting so losses through depredation likely to be more important.

I have had ponds with low stocking densities and high forage abundance where bluegill doubled or even tripled in weight over winter. For some reason they can not realize the same rate of growth on feed under similar conditions.

Aquaculture
Cooperative Research / Extension
Lincoln University of Missouri