Hope your actions bring you success Mike. Maybe we will get some colder weather this winter. It's been way to warm these last few years. Average Global temperature MEANS are above normal. It takes a lot of higher daily temperature readings thoughout the entire globe to effect the MEAN temperature readings for the entire year.
I don't know how deep your lake is. I do know that on Otter Pit down here in the new State Fish and Wildlife area the shad died a few winters ago when we had about 1" of ice on the pits surface. That pit has some very deep water. It's only 90 acres in total surface size but it's got 50ft deep areas. Not sure what the average depth is.
I wish I knew more about the life cycles of the different fish. They didn't teach that in my introductory fish classes.
I do know that there were dead shad or some kind of fish that was being eaten by some sea gulls. The gulls were walking along the edge of the ice and plucking fish out of the edge of the ice where there was a hole in the ice. This was on a day when it warmed up and the ice was starting to melt. It was at the North end of otter pit and there was a south wind that day. The windward areas were melting due to the warm air currents and the areas of ice that were protected from the winds were still frozen. It appeared that some of the fish were frozen in the ice itself. As I saw some gulls eating fish right off the ice's surface and not even near the free ice areas. I used some binoculars to watch the birds that day. So I think that if it gets cold enough your plan should help reduce the gizzard shap population.
I read that you once completely or almost completely drained your lake and wiped out the shap population only to have someone bring shad back into the lake a few years later. It's a crying shame that people think they know more about fisheries management that the DNR guys and bring those shad into watersheds where they don't belong. They compete against the bluegills and cause the sunfish populations to become starved and stunted. They change the entire lake ecostructure.
At Patoka Lake I read where the IN dnr first discovered a few shad in their survey nets in 1996 and by 1997 the shad population exploded and comprised most of the biomass at Patoka Lake. Great for the bass but really bad for the sunfish (bluegill) fishermen. Wonder if you could put in Hybrid Stripers to help eat the Gizzard Shad. They did that at Patoka Lake.
Regards,
Moose1am