Nervous water

[MuskieBait]

It is not unreasonable at all. There are many things in the river that will create funny current...

Submerged weed bed - create resistance in the current causing the current to slow down, thus creating a slightly broken and smoother surface (since the weeds then to sway so the surface is slightly broken as the resistance is never consistent)

Rock beds - depending on the size of rock, will create uneven resistance in the current causing the current to slow down, but a more broken surface

Sand flats - sand offers little resistance and is often easily disturbed thus the current does not slow down much, and the surface of the water is flat and smooth if the sandy bottom is flat

Sticks, logs, mussel beds...it takes careful observation to understand how they affect the current...and how to read it.

Fish is just another object on bottom. If the school of fish is numerous enough, and their combined size is large enough, it will affect the current just the same as rocks or weeds in the current. Fish that are moving around the school and waving their tail often could have the looks of submerged weeds (broken but smoother current that is slower). Fish that are holding tight to bottom not moving much may have little effect if they are small, but if they are the size of salmon in a small school then you may see the effects similar to submerged rocks or boulders.

And as you know, OT, a large school of baitfish in the surf, even when not attacked by predator, can be read by a difference in the surface of the water. The bait school, especially hundreds or thousands of smaller fish, such as bunker, mullet, herring...etc, resists the incoming surf current and the water flattens out over the school of bait. It can be read as a glassier area that is not expected to be so flat and calm.

I can sometimes read steelhead sitting in a spot up ahead where I cannot see them clearly, either behind a log jam or if the water was green and deeper, or if the water was shaded, by watching the water a bit and picking up subtle eddies, vortices or bulge that the fish cause if they happen to kick their tail a bit underwater, or if they rise or drop in the water column causing a disturbance in the current. It is often very subtle and you may not catch it if you are not paying attention.

It is all in the details