Water clarity is an indicator of the relative fertility of a lake. Fertility directly relates to phytoplankton productivity, which in turn relates to everything on up the food chain. So that's correct, TR won't be as productive in terms of numbers or total pounds of fish than other more fertile lakes. And for what it's worth, there are MAJOR efforts being made to protect TRL from heading further up the trophic ladder. Right now it's closer to oligotrophic than mesotrophic and a long way from eutrophic. That water clarity / trophic status is a large part of why the lake is such a popular destination.