That's an egg cluster of Hypeius Vengius worms. Look closely at the left photo and you can see some of them are well formed and about to emerge.
Their strongest passion is to breed and second would be vengence! Since you have disrupted that cycle I'm fairly certian that all of your future children and all of their children "Will be born Naked".
Sorry, that's the way it is around here in the winter.
Remeber to bleed your fish!
Almost looks like there was some kind of injury and that is an abscess. Yuk. Saw something similar in a moose we shot years ago, but I've never seen anything like that on a fish.
Just cook a few extra minutes and see what it tastes like... Let me know????
If a dipnetter dips a fish and there is no one around to see/hear it, Did he really dip?
Tell Tale Sign of Catch and Release!.
The leader was likely cut to release the fish and the hook festered his insides. The Bigger Females are immune to infection and are better suited for Catch and Release.
Thank You for putting this fish out of his misery.
"96% of all Internet Quotes are suspect and the remaining 4% are fiction."