ewest, I am pretty positive that Dr Dave has a good theory why the LMB and SMB are successful in larger waters. It is not a simple factor. I think it has to do with several factors of size of water body and fish behavior, which includes interspecific competition (crossing different species). The ecological principle of " lebensraum " could play a role in the co-existance of these two fish - adequate room for life or existance.
Larger water body size allows for, or increases the amount of space available for niche separation. When too crowded one of the species dominates, almost always the LMB. Competition between newly hatched YOY fish may be a part of the puzzle but I think it is a minor part. I think the major part is overlap of spawning behavior and availibility of sites.
