Where do walleyes stage?

Here’s the deal. I fish a few big MN/Ontario border lakes for walleyes in April before the season closes April 15th. One lake, I cannot find where the walleyes stage before they spawn in the river. The river enters the lake (it’s a deep lake trout lake) in a large bay that gradually drops to 40′. There is a rock pile near the mouth of the bay that comes up to 6′ then drops sharply back to 40′. Should I be looking for staging walleyes around that rock pile or up shallower in the bay?

I would wager that the walleye move into the river and stage in the holes and inside corners just outside the current seams.

Shallow areas during the day to warm eggs.