It's my understanding that periodically IFW samples lakes to estimate the health, population, and variety of lakes. They do it with gill nets, to have measurable results. The sad result is that most fish caught don't survive. It is too bad they can't have a charity on hand to harvest the catch. I don't think it's done often, unless there are issues needing to be addressed such as over- or under-population, disease, or invasive species. I believe most states have some similar form of monitoring.