Actually, this is where the Track Fish ability really comes in handy.  Using that, I was able to get 26 Golden Darter in 20 minutes from School of Darter and Brackish Mixed Schools.  I'm going to have to say that they're something recent though, as I've never seen them before, but it most definitely helped.  The School of Darter spawns seemed to spawn more along the streams north and northeast of Allerian Stronghold.