Good points gehajake!

Your way would definitely be easier, but I don't I have any elevation changes to work with.

I was going to build a two gate system between the forage pond and the main pond. I would then build the forage pond like a "paint roller pan" with a floor drain in the area between the two gates. Plan was to pull down the water level and then seine all of the forage into the gate gape. Close the forage pond gate and open the pond gate. If I was worried about predators, I could completely drain the gap between the gates as needed.

Although, I am going to try putting a very shallow FHM forage pond on top of one of my berms and use corrugated 4" drain tile pipe to shoot them into whichever pond would benefit the most from the minnows. (Who knows though, maybe the birds and raccoons will raid that little pond?)

P.S. anthropic has a forage pond above his main pond just as you have described in a little draw. I think he mostly uses it for supplemental forage BG growouts.