Another "twist" to all this is that most info on the barometer's effect on fish .... says it's is on relatively "shallow" fish. Fish in the deeper portion of the water column don't seem to be affected as much, if at all.

We already know that critters seem to know, sometimes ahead of time, when the weather is going to make a change. That change in barometric pressure could possibly be "felt" by them, and instinct or prior experiences may warn them of those changes. Nature's wild critters are usually more "in tune" with their surroundings than we are, since they can't artificially change them, so they've adapted to deal with them.