Farm raised salmon is salmon bred and grown in controlled environments rather than caught in the open ocean or rivers. Most of it is Atlantic salmon raised in large net pens anchored in coastal waters, though a growing share comes from enclosed tanks on land. It accounts for roughly 70% of all salmon sold worldwide, making it the most common type you’ll find at a grocery store or restaurant.
How Farm Raised Salmon Is Produced
The process starts in freshwater hatcheries, where eggs are fertilized and hatched in temperature-controlled tanks. The young fish (called fry) spend their first 10 to 16 months in freshwater until they undergo a biological shift that prepares them for saltwater, a stage called smoltification. They’re then transferred to ocean net pens, which are essentially large mesh cages floating in sheltered coastal areas like fjords or bays. The fish spend another 12 to 24 months in these pens before reaching a market weight of roughly 8 to 12 pounds.
Norway, Chile, Scotland, and Canada are the largest producers. Newer approaches include semi-closed containment systems that filter water between the fish and the surrounding ocean, and fully land-based recirculating tanks that keep farmed fish entirely separate from wild ecosystems. These alternatives aim to solve some of the environmental problems associated with open net pens, though they come with their own challenges around water quality and higher energy costs.
What Farmed Salmon Eats
The diet of farmed salmon has changed dramatically over the past two decades. Early salmon farming relied heavily on fishmeal and fish oil made from smaller wild-caught species like anchovies and sardines. By 2020, the typical feed formula had shifted to just 12% fishmeal and 10% fish oil, with 41% coming from plant-based protein sources like soy and wheat concentrates. Another 20% is vegetable oils, 13% is carbohydrate sources, and 4% is vitamins and minerals. A small fraction, about 0.4%, now includes newer ingredients like insect meal and microalgae.
This shift toward plant-based feed has real consequences for the fish’s nutritional profile. Farmed salmon still contains omega-3 fatty acids, but levels have dropped as fish oil in the feed has been replaced with vegetable oils. You’re still getting a good source of omega-3s compared to most other proteins, but a fillet today contains less than it would have in 2005.
Why Farmed Salmon Is Pink
Wild salmon get their orange-pink color from eating krill and shrimp, which are rich in a pigment called astaxanthin. Farmed salmon don’t have access to those natural food sources, so without a supplement, their flesh would be gray. Farmers add astaxanthin to the feed, typically at concentrations between 40 and 100 milligrams per kilogram of feed. Most commercial operations use a synthetic version of the pigment, though some premium producers use natural sources derived from algae or yeast. The pigment is the same molecule either way and is considered safe, but its use is one of the details that surprises people learning about salmon farming for the first time.
Antibiotics in Salmon Farming
Antibiotic use varies enormously depending on where the salmon is raised. Norway, the world’s largest producer, uses about 1 gram of antibiotics per ton of salmon harvested. That’s an extremely low figure, largely because Norwegian farms rely on vaccines instead. Chile, another major producer, tells a very different story: Chilean operations used an average of 530 grams of antibiotics per ton of harvested salmon in 2016, more than 500 times the Norwegian rate. The discrepancy comes down to warmer water temperatures in Chile that promote bacterial infections, along with differences in regulation and farming density.
If antibiotic use concerns you, checking the country of origin on the label is the single most useful thing you can do. Norwegian and Scottish salmon consistently rank lowest in antibiotic usage. Some certifications also address this directly.
Contaminants Compared to Wild Salmon
One of the most persistent concerns about farmed salmon is chemical contamination, specifically industrial pollutants like PCBs and dioxins that accumulate in fatty tissue. The data here may surprise you: recent testing of Norwegian salmon found that wild salmon actually contained about three times more dioxins and dioxin-like PCBs than farmed fish. Wild salmon averaged 1.48 pg TEQ/g of combined dioxins and PCBs, compared to 0.51 pg TEQ/g in farmed salmon. Standard PCB levels were also higher in wild fish (5.1 ng/g versus 3.3 ng/g in farmed). Mercury was similarly higher in wild samples.
The reason is straightforward. Farmed salmon eat a controlled diet that’s increasingly plant-based, which limits their exposure to ocean-borne pollutants. Wild salmon spend years eating their way up the marine food chain, accumulating whatever contaminants are present in the ecosystem. Both farmed and wild salmon tested well below the safety limits set by the European Union, so neither type poses a meaningful health risk from contaminants at normal eating levels.
Environmental Concerns
The biggest environmental issues with open-net salmon farming center on sea lice, escaped fish, and waste. Sea lice are tiny parasites that thrive in the dense conditions inside net pens. Wild juvenile salmon migrating past farms are 73 times more likely to pick up lethal sea lice infestations than juveniles in areas without farms, and farms can elevate lice levels in wild fish up to 40 miles from the pens. Since the parasites survive about three weeks off a host, the transfer window between farmed and wild populations is significant.
Escaped farmed salmon are another concern. When fish break free from pens during storms or equipment failures, they can interbreed with wild populations and weaken genetic fitness. The waste generated by thousands of fish concentrated in one area also settles on the seabed below the pens, which can degrade local ecosystems over time. These are the issues driving interest in closed containment and land-based systems, which physically separate farmed fish from wild environments.
Certification Labels to Look For
Two certification programs dominate farmed salmon: the Aquaculture Stewardship Council (ASC) and Best Aquaculture Practices (BAP). ASC certification is generally considered the more stringent of the two, with particular strengths in three areas: limits on the number of fish escapes allowed, restrictions on antibiotic use, and requirements for sustainable sourcing of feed ingredients. Both certifications cover environmental and social criteria, including water quality standards and worker welfare. If you’re comparing two packages of farmed salmon at the store, an ASC or BAP label is a reasonable indicator that the farm operates under tighter oversight than uncertified operations.
Nutritional Profile
A typical 6-ounce serving of farmed Atlantic salmon provides around 350 calories, 34 grams of protein, and 22 grams of fat. It’s higher in total fat than wild salmon because the fish are less active and eat a calorie-dense diet, similar to the difference between a pasture-raised and feedlot animal. Farmed salmon still delivers a meaningful dose of omega-3 fatty acids, along with vitamin D, B12, and selenium.
The higher fat content is a trade-off. You get a richer, more buttery texture and more calories per serving, but also a milder flavor compared to wild varieties like sockeye or coho. For people eating salmon primarily for the omega-3 benefits, farmed salmon remains one of the better dietary sources available, even with the shift toward plant-based feeds reducing omega-3 levels from what they were a decade ago.