Looks like its been stealing shiners! That 6" ling in its gut is wild.
Last year I put a 6" chub with a treble hook in it, back in the minnow bucket for future use. My dad, dumped the left over minnows down the hole (I did not condone this) and the next day we caught two huge ling. Well, my brother checked the stomach contents, lo and behold, there was the treble hook!
One way to guarantee higher ling catches is to drop the carcasses (perch, ling) back down the hole. They'll basically school up into a feeding frenzy.