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Atlantic and Pacific salmon: What’s the difference?

Smart supermarket shoppers know there’s a difference between Atlantic and Pacific salmon, but that difference goes beyond the quality of the fish.

by | July 21, 2022

Atlantic and Pacific salmon side by side.
Atlantic and Pacific sockeye salmon have different body characteristics. Atlantic salmon are more closely related to trout than Pacific salmon. Adobe Stock

Since before Alaska was even a state, marketers have sung the praises of wild-caught Pacific salmon over the less expensive farm-grown Atlantic salmon. 

You can see the difference clearly at the supermarket when the two kinds of salmon are displayed side by side. Atlantic salmon is a light pink with a soft consistency and mild flavor. Pacific salmon tends to be a richer color, with firmer flesh and more robust flavor. Typically, fresh Atlantic salmon from fish farms is available all year, while the availability of Pacific salmon is more seasonal — based on the timing of spawning season returns.

Consumers notice the difference in price as well: Pacific salmon can sell for between $15 and $25 a pound, while Atlantic salmon is typically $10 to $15 a pound. 

The difference between Atlantic and Pacific salmon goes deeper than how grocery stores market fresh fillets. The two kinds of salmon are entirely different species. They also have very different nutritional profiles. 

Let’s have a closer look at what sets Atlantic and Pacific salmon apart.

Salmon species: Back to biology class

Remember learning about taxonomy in biology class? There are seven levels of classification, and the last two — genus and species — make up the scientific name of an organism. 

Animals of the same species can breed with one another. That’s why a cocker spaniel and a poodle can produce puppies. Animals of the same genus but different species can usually breed. Some — like grizzlies and polar bears — can produce hybrid “grolars” and “pizzlies” that can breed. Others, like donkeys and horses, produce mules, but mules can’t produce baby mules of their own.

What does this have to do with salmon? As it turns out, Atlantic salmon and Pacific salmon are in the same family, Salmonidae, but they’re not in the same genus. There is only one species of Atlantic salmon, Salmo salar. The Salmo genus also contains dozens of species of American and European freshwater trout.

Pacific salmon, on the other hand, are in the genus Oncorhynchus. The Alaskan species of chinook, sockeye, coho, pink, and chum salmon fall under this genus. Two Asian salmon species and a handful of Pacific trout are also in the genus Oncorhynchus. 

This means that Atlantic salmon and Pacific salmon cannot breed with one another. Different species of Pacific salmon can interbreed to create a hybrid fish, but it’s rare. Pacific salmon species spawn on different cycles and are aggressive toward one another when their spawning grounds overlap.

Farmed vs. wild-caught salmon

Consumers in search of quality salmon should pay close attention to whether the fish they’re buying is farmed or caught wild. Farmed salmon live their entire lives in enclosed pens that float in saltwater bays and estuaries. Wild adult salmon live in the open ocean until they are ready to spawn. They have a natural homing instinct that leads them back to the freshwater stream where they were hatched. 

Salmon fisheries provided by the Cook Inlet Aquaculture Association (CIAA) and other Alaskan salmon hatcheries start with salmon that are hatched indoors and raised to the fry or smolt stage. When CIAA releases them into open bays, streams, or lakes, they develop the same homing instinct as salmon hatched in the wild. In fact, CIAA only uses broodstock from the Cook Inlet region to protect the genetic diversity from region to region. This and other measures make sure salmon produced by enhancement programs are nearly identical to wild-hatched fish.

Almost all Pacific salmon are wild-caught, including salmon fisheries provided by Alaska salmon hatcheries. Atlantic salmon are exclusively raised in fish farms. There used to be wild Atlantic salmon runs in every river in the Northeast U.S., but industrialization, habitat destruction, and overfishing has reduced these runs to a handful of rivers in Maine. Because the species is endangered in its natural habitat, you can no longer buy wild Atlantic salmon commercially.

When farm-raised Atlantic salmon mingle with wild Pacific salmon, there is no chance the Atlantic salmon will dilute the gene pool of Pacific salmon. However, Atlantic salmon can damage wild runs in other ways. In British Columbia, there are Atlantic salmon fish farms where farmed-raised fish sometimes escape into the wild. Farmed fish can bring parasites and diseases into the wild Pacific salmon population. They can prey on juvenile wild salmon and compete for other food sources. The good news is that escaped farmed salmon tend to stay close to their net pens and can be easily caught by local sport fishermen.

Atlantic and Pacific salmon fillets
Pacific salmon has a firmer texture and lower saturated fat content than its distant Atlantic cousins. Adobe Stock

The Quality of Atlantic and Pacific Salmon

American consumers eat more salmon than any other fish. The main draw are the high levels of omega-3 fatty acids, which can reduce cholesterol and boost memory. Atlantic salmon producers boast of advances in their industry that have improved quality — such as switching to plant-based feeds and reducing disease through vaccines and better breeding methods. Professional chefs still gravitate toward wild-caught salmon because of the diverse range of flavors and textures available on the market.

When the U.S. Department of Agriculture did a nutrition study in 2019 on three ounces of Alaska sockeye versus the same amount of its farmed cousin, some interesting differences emerged:

  1. Nutrition The 3-ounce sockeye fillet had fewer calories and nearly half the fat of Atlantic salmon. 
  2. Persistent organic pollutants — The same study found 16 times the amount of “persistent organic pollutants” in the farmed salmon. These substances are linked to type 2 diabetes, obesity, and stroke. 
  3. Cancer-causing substances — Both wild and farmed salmon have trace amounts of these chemicals. Wild salmon pick it up from pollution in the ocean, while farmed salmon get it from their feed. These chemicals are risky when you eat salmon in large quantities — and wild salmon is safer in more moderate quantities.
  4. Antibiotics — In the 1990s and 2000s, Chilean-farmed Atlantic salmon imports to Japan had higher than the legal amounts of antibiotics. This gave Atlantic salmon a bad reputation. Fish farms report that they’ve reduced their use of antibiotics, but it’s unclear how much. Wild-caught salmon typically does not contain antibiotics

See for yourself

If you would like to go right to the source of where Pacific salmon is raised in the Cook Inlet region, visit one of CIAA’s hatcheries.

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