It's one of those thing's that takes a little time and experiance to decide whether the fish is still in good enough condition to harvest.Like the other post replied,white belly is great,grayish is ok or so so,dark grayish is no way and then there is the total boot that is definatly a no go.After trial and error for a few season's you'll be a pro at deciding whether to keep or not to keep returning salmon.Even at that it still end's up being a 50/50 deal.Good luck,
STRIKE ZONE