The difference between a river and stockton is places for fish to be.  In a river most of the fish are concentrated in highly predictable areas, they are more opportunistic and the forage base is more varied and overall competition for food is more.  A lake like stockton is huge, there will be a large percentage of fish at any given time shallow looking, deep, suspended, following shad, roaming flats.  There is just much more water and food per fish.  Also rivers produce a smaller percentage of larger fish as they grow much slower.  Well...ya the reason people hang out in the cove after a tournament is cuz they know there will be a very high percentage of large fish in a small area.  I am not saying that fish cant/arent recaught, I just think we as anglers are naive to think  we catch all the big ones.  Ask a diver who dives a lake!