I emailed Michael Allen who was part of the group form Florida that performed a study on whether fishing during the spawn has impacted the fish population. He replied as follows:
"Briefly, our results were not specific to reservoirs or rivers, they were obtained from reviewing tagging studies and creel survey data nationwide (included lakes, reservoirs, and rivers). We evaluate the proportion of the total fishing effort that occurred during spawning, and used tagging studies to evaluate what proportion of bass are caught during spawning. We put all this information into a computer model. The results indicated that in most cases spawning season closures would not improve the number of bass in lakes. However, in cases where fishing pressure is very high there could be impacts. That's the short take home message, hope this helps".