Coley,
Do you know anything about the size of the nearby lakes compared to Strobel?
It is hard to tell from the videos I've seen, but Strobel looks like a pretty good size lake. I wonder what the acreage is on it?
Perhaps a bigger lake would spread out the fish more and offer less competition for food, thus the increased growth rate.

Strobel also looks like it goes through some pretty good fluctuations in the water levels based on the high water marks. The dry white rocks look similar to some of our eastern Washington lakes with higher alkaline water contents.
SF