People don't have to go over their limit to kill a fishery...
A typical winter, Valens may be open from mid-Jan to mid-March. So say that's 2 months or 8 weekends.
During its prime, I saw at least 100 ice anglers on the lake. But for argument sake, let's say 100 anglers.
At the time, seasonal limit for Black Crappie was 25. Even if we assume only half the anglers would keep their limit of crappies, that's 50 anglers x 25 crappies = 1250 crappies taken on a single day. Now multiply that figure by 2 for the weekend, then multiply that by 8 for the number of weekends...we have not even consider the anglers fishing on week days...which there were an average of 15-20 on any given week day...mostly locals.
That little fishery cannot sustain this kind of harvesting...even if people fish within limits.
The problem was that Valens got popular as a great panfish fishery and people started to come in droves...and families came to fill buckets full of big Bluegills and Crappies. After several years of this harvest, the fishery crashed.
People often ask "Hey, where can I find good fishing?"...and I rarely reply. It's one thing being helpful...but it's another thing to start naming fisheries on the internet where hundreds and perhaps thousands of people can see the same information...and the crowds start to build up on any named spots. Fisheries cannot sustain that type of pressure.