So why is wild salmon a deeper red than farmed salmon?
Unlike beef, which acquires its distinct red hue from contact with oxygen in the air, salmon meat gains its color through the fish’s diet. Out in the ocean, salmon eat lots of small free-floating crustaceans, such as tiny shrimp. These crustaceans are filled with molecules called carotenoids, which show up as pigments all over the tree of life. In fact, if you’ve ever known a kid who turned orange from eating too many carrots, you’ve seen carotenoids in action. It’s these carotenoids that account for the reddish color of the salmon, as well as the pink color of flamingoes and the red of a boiled lobster.
Farmed salmon, however, aren’t fed crustaceans. Instead, they eat dry pellets that look like dog food. According to the Atlantic Canada Fish Farmers Association, salmon chow includes ingredients such as “soybean meal, corn gluten meal, canola meal, wheat gluten and poultry by-products.” Carotenoids, which are also essential for regular growth, can also be added to help give the fish its distinctive color.
Clearly, color counts. But as Tammy Davis notes on the Alaska Fish and Wildlife News blog, color isn’t the only thing that makes for a tasty fish:
Some king salmon – about one in 20 – have white meat due to an inability to process these pigments in their food […] In past years white king sold for about sixty cents less per pound than the more familiar red-fleshed king, and some fish buyers enjoyed this rarer king salmon for a bargain. Nowadays many believe white king’s flavor is more delectable than their more common cousin. The marketing tide has turned and now the fairer fish, marketed as “ivory king,” brings a higher price.
Wild salmon are pink (or pinkish-orange, depending on geography) for the same reason flamingos are pink: their diets, which are heavy in krill and shrimp. But farm-raised salmon are fed a diet that renders them gray… or it would, if they weren’t carefully “pigmented” to transform into more appetizing hues.
The Atlantic reports:
While [astaxanthin, an ingredient in the pigment pellets,] provides the salmon with some of the vitamins and antioxidants they’d get in the wild, salmon health isn’t the selling point.
It’s the “pigmenting,” to use feed industry parlance, that really matters, letting salmon farmers determine how red their fillets will be. (Thanks to a 2003 lawsuit, they have to alert customers to the fact of “added” coloring.)
To facilitate that selection process, pharmaceutical giant Hoffman-LaRoche developed a set of standardized color cards to measure hue — which is now known as the DSM SalmoFan. (Dutch multinational DSM acquired it in 2002).
If it’s price that’s keeping consumers from buying wild-caught salmon, they might want to consider saving a few bucks more and start demanding farmers cut out those expensive pigments—and sell them salmon that’s gray.