Okay, now I get it. I guess the best answer I could give would be "I don't know". I suspect with all the big fish in the rivers they might just be laying low to avoid being a meal for somebody. Most of the Brookies I fish for are located in small, remote, headwaters streams, and while not particularly allusive, they can be easily frightened and "put down" by my clumsy, stream side fumbling.
Again, I'm just guessing but since big fish eat small fish, I'd tend to think the move into locations that would make them less available as a food sources for the steelhead and coasters in the river. Since these secondary or tertiary lies are probably not typical places to fish for these bigger fish, this might account for the apparent absence. I doubt they stop eating entirely during this time but I bet they are a lot more careful about when and where the choose to feed. Remember, I'm just guessing!