I believe the crawdad loss is for reasons other than rocks and gravel, saw some odd looking crayfish in the '90s for a few years and then near none since. I suspect exotics took over then eventually died out, no proof. Think Indian Creek still holds good numbers of crawdads, it did a few years ago. It doesn't flow from Ar or a golf course either and that may make a difference.
My point was, is there evidence that those streams can support a great number of larger fish? Won't the predators outnumber the prey at some point?
I have fished, waded, swam in the two sugar creeks since the mid '50s and I see probably ten times fewer fishermen on the whole drainage than there were back when. More floaters on the Elk/Cowskin, but really few fishers and they mostly go back where they came from after the weekend, imo, any loss of fish quality/size / quantity is unrelated to the consumption. I grew up with stories of seining those streams with hog wire and two teams of horses, hauling a wagon load of fish at a time; the old ones didn't fish for sport.
Heard anecdotes of hand catching cats over fifty pounds out of those creeks too. It may be our modern methods keep us from seeing the real big fish or that mans desire for green grass is killing the streams' historic character.