It was funny a few days ago I was trying to catch shad using a castnet from a creek, but instead I kept catching crappie after crappie. I caught (and returned) several times more crappie that shad from the creek in question.

I don't think that's correct regarding stagnation and water flow exactly. Having a boat with a graph with side scan takes the mystery out of it for me though. I know places where they stack up in current and other places where they stack up in slack water. When they stack up well either way it is the easiest crappie fishing there is, the colder the better.

I think shad have no idea where they are at in any body of water to be honest but rather they simply move faster or slower in a random direction based on various conditions. (this is what many simple animals do but I forget the biological term) So if it is too hot or too cold they will swim faster and if it is Goldie Locks sort of conditions they will slow down. So if it is a slough or a creek that does not stretch back deeply with a depth greater than 3', the shad ping pong around until they all ping pong out of a spot when it is too cold. It's sort of like those robot vacuum cleaners. Imagine places where the robot would get stuck and never be "smart" enough to randomly find themselves back to their recharging base, like some long twisted narrow corridor. Usually if a creek goes back more than 1/2 mile with a depth or 3 feet or more from a main lake it will always have crappie or at least I've rarely found one that didn't when I had a boat with a graph to "cheat". Now getting them to bite well can be another story.

There are factors though. Sometimes it is as simple as sandbass taking over a creek and pushing the crappie out or to other spots. Sometimes cold current "pushes" out shad, while warm current "sucks" them in.

This is a great subject! I enjoyed this topic and have learned some from reading the posts. I've heard the few creeks at Hubbard creek are amazing during winter but never have heard ppl doing good at my home lake, Fort Phantom which has a creek with similiar depth (about 10 feet in middle). The creek right now at Fort Phanton is almost 8-10 degrees colder than the main lake so I don't buy the theory that the creeks are "warmer" as a blanket statement for all lakes during winter. I do wonder if Crappie move into these creeks as we get consistently warmer days since the shallower more stagnant wind protect creeks warm faster just as they are cooling faster the last few months and currently?

just like the spawn, water temp has nothing to do with where wintertime crappie are located.