Here’s the responce I recieved from Daryl Bauer with the Nebraska Game and Parks.
Quote:
May and June are always the best months for walleye fishing in Nebraska reservoirs because we have post-spawn, hungry fish then, and the young-of-the-year (YOY) baitfish, gizzard shad especially, are not yet present. I expect to see some “skinny” hungry walleyes 3 weeks after the spawn every year. The young-of-the-year shad should just be starting to show up now. I suspect the shad hatch may be a little behind schedule. One of our biologists fished Sherman last week and said he saw LOTS of schools of very small shad, an inch or less, so I think they are on their way.
I know why you are concerned though. Shad, especially small shad, will always die-off during the winter, but we have evidence that what really knocks the shad numbers down during the winter are actually winters where we do not get ice cover until late in the winter. Once you get ice cover it stabilizes conditions. When there is not ice cover until late, the water keeps mixing and cooling and that really knocks the shad back. Last winter was a winter like that, and you know better than I do that we had some of the best walleye fishing through the ice last winter that I can ever remember, on several reservoirs around the state. I believe that might have been because the numbers of small shad were depleted by the time we finally got ice cover.
Actually the “ideal” shad population is one where most of the shad die every winter. You only need a handful of survivors to produce all the YOY shad you need. If you have a lot of shad that survive the winter, that tends to suppress the production of YOY shad the next year. Since gizzard shad grow so darned fast, you need that production of YOY each year so that there are appropriate-size prey for most of the predators to eat.
On reservoirs far enough north and west that gizzard shad have a hard time surviving the winter, we have stocked a few adult shad on an annual basis, and those few adult shad will produce all the YOY needed. We typically stock shad adults like that in Lake Minatare annually. We typically help Colorado and Wyoming with some shad collections for some of their walleye waters every year. We have never had to do that at Sherman. We did do that this year at Elwood, but that was mostly because we believed the low water levels there had resulted in less prey fish there.