America's Test Kitchen on cooking wild vs farm-raised salmon

America’s favorite fish, salmon, is fairly amazing. Wild salmon are born in fresh water, spend most of their lives in the sea, then return to the very same waters where they were born to lay their eggs, die, and fertilize the surrounding ecosystem. However, most of the salmon we eat is farmed and doesn’t live that same active life. Our managing producer Sally Swift wondered if that affects how we should cook wild versus farm-raised salmon. As it turns out, it makes a big difference. Dan Souza, executive editor of Cook’s Science at America's Test Kitchen, explains why. [Ed. Note: Dan also shared two salmon recipes – Miso-Marinated Salmon and One-Pan Roasted Salmon with Broccoli and Red Potatoes.]

Dan Souza Photo: America's Test Kitchen

Sally Swift: I have a question about salmon that occurred to me last week when I was cooking up some game birds that a friend had given me, and realizing how different they are from regular farmed birds because they're wild. I started thinking, is wild salmon different from farmed salmon?

Dan Souza: It’s an interesting question and you've made a nice comparison there to game birds – and maybe chicken – that you'd normally be cooking at home. There's a big difference between wild salmon and farmed-raised salmon. I know we look at them as being the same thing, but they’re not. Like most things, it all comes down to lifestyle. Farm-raised salmon lead a sedentary life; they’re in a small cage or a small tank. They are fed a lot so they grow quickly. That kind of lifestyle leads to two different things. One is muscles that aren't as well-developed, so the collagen in farm-raised salmon has fewer chemical cross-links, it's less structured than it is in wild salmon. They also have more fat. The fattiest farm-raised salmon has about four times more fat than the leanest wild species.

SS: Wow! That is crazy.

One-Pan Roasted Salmon with Broccoli and Red Potatoes Photo: Keller + Keller

DS: When it comes time to cook them, that has a huge impact. If you cook a fatty steak, it stays juicy even if you overcook it by a little bit. When we cook wild salmon, we find that when it's cooked to 125 degrees – which is our preferred temperature for most fish and for farm-raised salmon – it tastes a little dry. That is because it has less fat, and the muscles fibers are already a little bit firmer.

We did a test in the kitchen – which was interesting and showed us a lot – where we cooked wild and farm-raised salmon to two different internal temperatures: 120 degrees and 125 degrees. We used a digital instant-read thermometer just as we would when cooking steak. We had people try both samples at both temperatures, and every single person preferred the farm-raised salmon cooked to the higher temperature of 125 degrees. We tried five different wild species, and everyone preferred them cooked to 120 degrees – so five degrees less.

Miso-Marinated Salmon Photo: Carl Tremblay

SS: With the prices of wild salmon, it sure makes sense to know how to cook it correctly. Can you give me a quick primer on some of the names of wild salmon, because I think sometimes we don't realize what's wild and what is farmed?

DS: Absolutely. When you're at the store, you'll see farm-raised Atlantic salmon. Farm-raised should always be labeled as “farm-raised.” But if you see “Atlantic,” it has to be farmed-raised because it's illegal to catch wild salmon from the Atlantic Ocean. Everything else is going to be your wild species, so you have Chinook, also known as king salmon. There's coho, which is also known as silver. You also have sockeye salmon, which is common and has a very dark flesh. Some of the less common ones that are often used in canned salmon are pink and chum, which you probably won't see as much. King salmon is considered the king of wild salmon. It'll have more fat than the other species, it’s a much bigger fish, and it's a darling of chefs, people really like that one.

SS: Do you have a salmon recipe you go to all the time that you love?

DS: Yes. At America’s Test Kitchen, we have a ton of great salmon recipes. One that I love is a miso- marinated salmon. For it, we make a mixture of miso, sake, mirin and sugar, then coat skin-on salmon fillets with that, and let them sit for a fairly long time – at least six hours and up to overnight. What happens during that time is a lot of the moisture – the kind of the surface moisture of the fish – comes out and the flesh firms up in a nice way. We get tons of great flavor from the miso, a lot of savoriness and some sweetness. It's a simple dish to serve, basically preheat the broiler and it goes underneath. The sugar, miso and protein browns nicely so you get this kind of mahogany exterior, and the inside of the fish is silky. Tons of flavor in a really simple recipe.