I am pretty damn sure that the guys with the gill nets are able to catch fish all day long when those of us using a hook (of any kind) are going home empty-handed.
I have personally seen it myself when I worked for a commercial fishery chasing carp on Sak and Audubon. We'd pull a 500 ft seine as defeated walleye chasers left an area in the hopes that it would be mostly full of carp, only to have a shitty morning of sorting and saving all of the game fish before the carp beat them to death.
And I'd guess most of you have seen it as well while in Cabelas. When I lived in GF, I was always amazed at the number of times I'd go by the aquarium in Cabelas and see walleyes hanging out motionless as small schools of minnows darted in front of them.
Mind you, this obviously doesn't mean walleye can't and don't swim up and down the river, but the notion of there being a large school of walleyes that starts out down in Lake Oahe and migrates northward into areas where there isn't already a lot of walleyes is bunk, pure bunk.