Tough to tell being you are directly over them. Any snapshots with them off to the side? If this lake has shad I would guess large shad.
Here's one of my favorite snapshots with my 997 that shows a school of fish under a school of minnows.
Baitfish tend to look ghost like where as fish are more solid white.
It's also interesting that you are set at 75' left and right which seems to be very common. I for some reason really like setting it at 125'.