Drifting walleye rigs on bottom a couple of weeks ago on a big natural lake in northwest Wisconsin, I saw lots of this. I'm assuming clouds of baitfish. What do you guys think? (sorry about the glare) Thanks.

Def looks like bait to me 

Several years ago, I was frustrated from seeing this kind of stuff on my screen all the time especially if I was crappie fishing and couldn’t catch anything when I thought I was looking at fish. I bought an Aqua-View camera to try to see what I was looking at. In the dozens of times I’d drop the camera down, I never saw those “blobs” become fish. Most of the time, it was clouds of leaves or weeds or something else I couldn’t identify. Because of the amount of time I wasted dragging out the camera and staring at the screen was taking away from my fishing time, I gave up and got rid of the camera.

I use my electronics to find structure and cover rather than looking for fish.

Then I fish the structure and cover.

Could be clouds of baitfish/minnows.

 

I've also seen them be hatches of bugs too.  Certain species hatch out of the bottom of the lake and float to the surface.  Usually the fishing is bad when this occurs because the fish are gorging on them.

could be submerged trees or bush.    

That first screen is definitely bait balls.