Greetings fellow 'eye fans! Newbie here. I'd like to add some personal experience to this very interesting thread.
In the '90s I revived and ran an old spring-fed trout hatchery. What I lacked in formal training I made up for in enthusiasm for everything fish (and books from the University library).
Once I had the trout production operating well, I decided to try to raise walleye too. The facility was a flow-thru 58 degree raceway setup. This precluded the ability to use plankton ponds like the state boys do, so I had to try to get the fry on "store-bought" feed like my trout were. This was something that there was almost no industry success at, and absolutely no literature on. I solicited the advice of a very cooperative USF&W fellow from the Bozeman, Mt. facility who was trying to do the same thing.
I arranged to buy 70,000 walleye fry from another hatchery, and when I met the truck at midnight at the 65/412 junction, some of the fry were still hatching. Walleye fry are... very tiny... new hatches are about 3/16" long and skinny as all getout.
Within 3 days they've used up the yolk sac (the only free lunch they'll ever get) making them even smaller. They're programmed to begin eating live food at day 4, and the only thing fitting that description in a size they can ingest is zooplankton.
Feed particles for trout fry (powder actually) were too big for the walleye, so I had purchased some very expensive developemental feed suggested by my F&W buddy that was screened to the appropriate micron partical size for walleye. Only a small percentage of my fry would eat it though, given the previously mentioned penchant for live feed. They soon found that live feed source though... each other. By day 7, I was seeing large numbers of fry with a sibling in their mouth (hard to swallow someone your own size). A day later, the uneaten portion having fallen away, they swallowed and digested the rest. It didn't take many days of this before the cannibals were noticeably larger than the fry that took my feed, so you can guess the fate of my "farmable" fish. By week 4, I was down to approx. 5,000 1/2" fry, all cannibals that wanted nothing to do with my feed. Even my F&W buddy with much greater resources fared little better than I at the fry stage, though he eventually had some limited success getting much larger fingerlings on the feedbag.
The AG&FC Centerton hatchery prepares plankton ponds long in advance by calculated fertilization with hay and prepared fertilizers. The ponds must reach a certain density of zooplankton by the 4 day post hatch date which is a serious challenge given the weather at that time. Raise a jar of that screened pondwater to the light and you can see millions of tiny little critters twitching about (and there's even more you can't see). It's a critical timing game as a few cloudy cold days can wipe out a zooplankton crop.
The point of this ramble is to shed a little light on natural walleye recruitment, in particular for the WR chain. The old pre-impoundment White River had a distinct seasonal temperature/nutrient profile that apparently supported the critically timed zooplankton bloom needed for walleye fry survival. Those conditions almost never exist in today's tailraces, or for that matter, many miles downlake, primarily because the waters don't warm soon enough to support a decent zooplankton bloom. Adult fish can go a month or more with little to no food, but the tiny fry go belly up in a couple days, and they don't have the option of swimming a long ways to find it.
Nobody told the spawners that they're largely wasting their time spawning in the tailraces though (or maybe they don't care) so large numbers head for the biggest party in town every year. The remaining free-flowing rivers that feed the WR chain can support some natural recruitment, but it's a numbers game (small river, big lake). Stocking supplemental fingerlings at a time when there's plenty of appropriately-sized live food to thrive on gives the best bang for the buck, and even that method is subject to many variables.
(I hope that's not too windy or off topic)