I fished a small lake today (probably a 5 acre lake, max depth of about 6') and easily caught a bucket full of pumpkinseeds (there are no other species of sunfish in this particular lake). The smallest one went 7' and the biggest just over 9'. I can't ever remember catching nothing but keepers.
What does this mean for the biology of the lake? I have fished lakes full of nothing but throwbacks, and people have told me to keep smaller ones to give a little more food for the rest - but I've never encountered this situation before.
The only other species of fish in the lake are perch, largemouths, and pickeral (and there are a ton, I caught a dozen when targeting gills).