A friend who is a retired WDFW manager told me that hatcheries can add crushed crab and shrimp shells in the food to get fish with pink/orange colored flesh. Commercial hatcheries like Trout Lodge and Pacific Aquaculture do this to make their products more attractive in the stores. The shells are a waste item from seafood processing plants, and are inexpensive.
He said WDFW once did an unscientific blind taste test (not sure how many people), and the pale flesh tasted just as good as the pink/orange. Maybe so, but it sure looks tasty!