“TVA biologists monitor the levels of vegetation in their reservoirs,” Martin said. “They does flyovers every year, and we have a lot of data on surface acres of grass on Kentucky Lake going back decades. You would think that grass would improve the survival of juvenile fish enough to impact the spawn in a positive way. That thinking would then say we could use the amount of the grass coverage in a lake to predict the success of the spawns.
“But the data doesn’t show that. When you plot them together, you see that some of highest years for grass coverage were some of our lowest spawns and some of our lowest grass coverage years are some of our best spawns. So that is not a predictor of spawn class success. There is no real relationship there.
“It makes fishing more fun, but those main lake grass beds don’t seem to improve the spawn on Kentucky Lake. Also, when it’s a good spawn on Kentucky, it’s almost always also a good spawn on Barkley. And, Barkley has almost never had grass. In some lakes, the amount of aquatic vegetation can be hugely important, but at Kentucky and Barkley, it’s harder to make that case.”
Read more at: https://www.wired2fish.com/fish-biology/largemouth-bass-populations-what-affects-bass-fishing-on-large-reservoirs/#slide_5