I’ve been unzipping my walleye fillets for several years now. It’s just a habbit. I’ve had fish at friends and you know pretty quick if the don’t do it. It works on other species as well. That strip has a heavy blood line in fish like white bass and catfish. It deffinatly improves taste in fish like that.
Another thing I started doing several years back is bleeding my fish out before cleaning them. I keep a small pair of sissors in the boat and just before the boat ride in at the end of the day I cut their gills on both sides. They bleed out rather quickly and the difference it makes is unbelievable. Not only is the meat as white as can be but the fish is also dead so you don’t have a chance of him making the big flop when getting ready to fillet them. I can remember getting cut by a gill plate when they flopped at the wrong time. Since bleeding them out, it’s never happened. Another bonus of bleeding out your fish is that it’s much cleaner when you fillet them. This is really nice during the time of year when fish cleaning stations might be closed and you have to clean them at home in the kitchen. I also think it improves the taste. (Not that walleye really need an improved taste.)