All 4 appear to be mature adult male pure northern BG. If you going to thin your BG out, I would try not to remove your larger males, but rather focus on females. All fins appear to have normal length and coloration for BG and the operculum(ear flap) does tend to get longer than many think in large adult males. If those BG were hybrids, you would see coloration other than all black into the operculum.

Which fin were you referring to?