Sometimes I wonder why lakes such as belton, with the super threadfin shad population is just a fair crappie lake.
Waco in my opinion has less shad, but a much higher crappie population. One thought is, that it is a fact that the young threadfin shad , compete for the same food(plankton), as the newly spawned crappie do.
If the winter is mild, and there is no shad kill for several years, then the shad population could become out of balance. threadfin live 2 to 3 years if no winter kill.
Over a 3 year period, with no mass loss, thats alot of shad that will potentially survive.
Just another piece in the puzzle to consider, on yearly crappie populations.
On the other end of the spectrum, take a lake like stillhouse , it is usually very clear, due to a lack of nutrients and plankton, and has a scant shad population, and also a scant gamefish population.
Fertile lakes with healthy fish populations really have to maintain a good balance .. Alot must go right .

Post, How cold does the water temp on a lake have to get to kill shad?

They start to die off at 42 f

I thought it was close to 45 degrees. Thanks Stuart.

I am not sure about the numbers of shad being an issue, more so the overall lake fertility. Belton, not sure about Stillhouse, does not have near the organic matter decomposing in the water as Waco. With the past years of drought, this has multiplied the effect. Not to mention the spawns were probably reduced or not as good. Belton is mostly rocky bottom and bluffs. Waco is muddy/sandy bottom with tons of trees and some vegetation. I would expect Belton to start getting better again with some years of sustained water levels.

This^
I don't think the shad population has a great impact on the spawn. Lack of zooplankton will affect survival of the spawn. And threadfin shad do eat several types of plankton. But threadfin shad rarely live beyond 3 years usually 2 years. Waco does seem to have higher shad and crappie populations than Belton with it's low water fertility.