I fish a river alot for black and white crappie. They tend to move frequently in rivers and contrary to what "experts" say , i have found them in current more times than not. Sometimes directly in it and sometimes on the breaklines , where current meets slack water. My advise would be to vary your depth and try something you don't think would catch 'em. I have caught 'em here in the river in 38 degree water a foot or so below the surface.