As regards your large crappie population declining; I have fished several watershed lakes where we would sometimes have an excellent crappie day and catch several crappie up to 16" and a whole stringer of 13-14" crappie to fillet. However, we never had a lake that would produce like that consistently. Our best crappie lakes always seemed to cycle up and then down.
Is there is a chance that we caught enough crappie on our best trips to dent the population of large crappie? My cousin's watershed lake up near Eureka was one of our good ones, and that one is usually about 35 surface acres.
My (non-expert) opinion is that you will probably get a big crappie spawn one of these springs, and 3-4 years later will once again have a nice population of large crappie in your lake. If in Year 2, you have thousands of stunted crappie, then you are going to have to cull a lot, to once again hit your large crappie goal.
P.S. My father once brought home a huge white crappie from the lake I described above. It weighed 3-1/4# at home. He said he caught it first thing in the morning, so it might have weighed 3-1/2# when caught. All of the rest of the "large" crappie we caught in that lake were right at 2 to 2-1/4#. Nothing else ever came close to the biggest crappie. I don't understand how that happens in a presumably "bell curve" population for crappie weights. I suspect some fish are just genetic or endocrinological freaks.
