I don't think size of lake matters as much as oxygen levels in winter. If the lake has some incoming source of water through the winter so fresh oxygen is entering then there should be no winter kill. Snow cover and ice depth can also be variables that effect oxygen levels. Some lakes have frequent die offs and others never do. I was told by a C.O. at Beautiful lake in Manitoba Duck Mountains that I should keep the fish I catch because they were likely to die off anyway. Other than finding a way to get oxygen into the water there isn't much can be done.