Crazy amounts of spawning certainly helps create a productive forage base. However, there are many other important factors.
6# LMB in Ontario are not eating PS fingerlings, they are eating very large PS. Your good bass lake almost certainly has very favorable conditions to raise large PS.
Also, how big are the biggest rock bass? I have fished with kids in Ontario and caught a rock bass every cast that would certainly be an excellent meal for at least a medium-sized bass ... and a meal for the next day ... and a meal for the next day.
Finally, you did not list yellow perch in the lake population. If that lake does have them, a long (fusiform) YP is a lot of calories that are easily swallowed by a big bass.
Thanks for the info, the bass lake is relatively small and Ive fished all of it many times - shoreline and deeper water. Only a few spots with rockbass about 7 inches max size i've seen. I forgot about the perch - max size is about 5 inches but most likely bigger exist of course.
The PS max size ive seen is just over 9 inches - they get pretty chunky.
