Wild vs Farmed Salmon — Which Should You Buy?

A 100 g cooked portion of wild Atlantic salmon delivers roughly 1.5–2.0 g of combined EPA + DHA. Farmed Atlantic salmon lands in a similar ballpark — about 1.5–2.2 g per 100 g — because the higher total fat content of farmed fish pulls the absolute omega-3 numbers up.¹ Among wild Pacific species, the fattier King (Chinook) salmon can reach roughly 2 g per 100 g, while leaner Sockeye sits around 1.2 g.¹

But the omega-3 to omega-6 ratio tells a different story. Wild salmon typically runs about 1:1 — a balanced, anti-inflammatory ratio. Farmed salmon, especially modern fish fed increasing amounts of plant-based oils (soy, rapeseed), leans toward 1:3 or even 1:4 — still far better than most processed food, but distinctly more omega-6-heavy.² This matters because omega-6 fatty acids compete with omega-3s for the same enzyme pathways; a high omega-6 load can blunt the conversion of short-chain omega-3s (ALA) to the long-chain EPA and DHA your body actually uses.

There is also a trend worth knowing about: as farmed salmon feed has shifted from fish oil toward plant oils over the last 15 years, EPA and DHA content in some farmed populations has measurably declined. A Scottish analysis found a significant drop in farmed Atlantic salmon EPA and DHA between 2006 and 2015.³ The industry knows this and is working on alternative omega-3 sources (algae oil in feed), but the fish on your plate today may carry less than the historical numbers suggest.

Wild salmon is one of the richest natural food sources of vitamin D on the planet. A 2020 Norwegian analysis found wild Atlantic salmon from the Baltic Sea contained 18.5 ± 4.6 µg of vitamin D₃ per 100 g — roughly 370% of the daily recommended intake in a single portion. Farmed salmon in the same comparison delivered 2.9–9.5 µg per 100 g, depending on feed composition.⁴ Other analyses have found wild Pacific salmon carrying up to eight times more vitamin D than farmed Atlantic salmon.⁴

The reason is straightforward: wild salmon accumulate vitamin D through their natural diet of zooplankton and smaller fish; farmed salmon get whatever vitamin D is included in their formulated feed pellets. In northern latitudes where sunlight is scarce for half the year, that difference is not trivial.

Selenium is abundant in both, but Norwegian monitoring data actually puts wild salmon slightly ahead — along with somewhat higher copper, zinc and iron — most likely reflecting a wild diet of whole prey fish and crustaceans versus formulated feed.⁵ Both still deliver more than 30% of the daily recommended intake in a standard 140 g portion.

Protein is similar in absolute grams, but wild salmon is leaner — meaning you get more protein per calorie. Wild salmon also contains natural antioxidants like astaxanthin (the carotenoid that makes salmon flesh red), which farmed salmon receive as a synthetic supplement in feed to achieve the same colour.

This is the part of the conversation that has done a U-turn in the last 15 years, and popular perception has not caught up.

In the early 2000s, a landmark study found that farmed salmon — especially European-farmed — carried significantly higher levels of PCBs, dioxins and organochlorine pesticides than wild salmon.⁶ These persistent organic pollutants (POPs) accumulate in fish oil, and farmed salmon were eating concentrated fishmeal and fish oil from smaller fish that had themselves bioaccumulated these compounds over their lifetimes. The study generated headlines worldwide and cemented a narrative: farmed salmon = contaminated.

Then feed changed. Modern salmon farming has replaced much of the fish oil with plant oils — partly for sustainability, partly for cost. A 2020 Norwegian study that updated the picture found the opposite: wild Atlantic salmon now carried roughly three times higher concentrations of dioxins and dioxin-like PCBs than farmed salmon.⁷ Wild salmon averaged 0.53 pg TEQ/g for dioxins and 0.95 pg TEQ/g for dioxin-like PCBs, while farmed salmon showed lower values across the board. Norway’s 2024 monitoring programme confirmed that farmed salmon continues to test well within EU safety limits for all monitored environmental pollutants.⁸

Why are wild salmon now higher? Because POPs from decades of industrial pollution persist in marine food webs, and wild salmon eat across those webs for years. Farmed salmon eat formulated feed from controlled sources — the feed has become cleaner than the ocean. Both wild and farmed salmon remain below EU maximum limits, but the direction of the difference has reversed.

Ethoxyquin — a synthetic antioxidant used in some fish feed to prevent fat oxidation — deserves a mention. It is approved in the EU at low levels, but has been found in farmed fish at concentrations above what is permitted in other foods, and its long-term human health effects are not well studied.⁹ It is not a reason to avoid farmed salmon, but it is a reason to favour producers who disclose their feed practices.

This is where country of origin matters enormously — far more than the wild/farmed distinction itself.

Norwegian farmed salmon is the success story. Norway’s aquaculture industry has reduced antibiotic use by 99% since the late 1980s, largely by developing effective vaccines against bacterial diseases. In 2024, total antibiotic use across all Norwegian fish farming was 709 kg — for context, that is less than a single medium-sized pig farm in many countries. About 99% of Norwegian farmed salmon are raised without any antibiotics.¹⁰ Norwegian monitoring consistently finds zero antibiotic residues in the final product.

Chilean farmed salmon is a different story. Chile is the world’s second-largest salmon producer, and its farms use antibiotics at rates hundreds of times higher than Norway’s — driven by a bacterial disease (SRS, salmon rickettsial syndrome) for which no effective vaccine exists. Chile used roughly 380 000 kg of antibiotics in salmon farming in a recent year — over 500 times Norway’s total.¹¹ This intensive use creates selective pressure for antimicrobial resistance, and resistant bacteria emerging in Chilean salmon farms can share resistance genes with human pathogens through horizontal gene transfer.¹¹

Scottish farmed salmon sits between these extremes — antibiotic use is low by global standards but has been rising in some years, and the Scottish industry has faced scrutiny over inconsistent reporting.

The practical takeaway for a shopper: antibiotic residues are not the issue (routine testing catches them). The issue is the evolutionary pressure that heavy antibiotic use in some producing countries exerts on the global pool of antimicrobial resistance — a problem that affects everyone, not just the person eating the fish. If you are buying farmed salmon, country of origin is your single most important piece of information.

Bodil asked directly: are farmed salmon stressed? The numbers say yes, and at a scale that is uncomfortable.

In 2024, approximately 57.8 million farmed salmon died during the sea phase in Norway alone — a mortality rate of 15.4%, down slightly from a record 16.7% in 2023 but still meaning that roughly one in six fish never makes it to harvest.¹² Add hatchery mortality (45.8 million fry died in Norwegian hatcheries in 2024, the highest ever recorded) and the total dead fish count is over 100 million in one country in one year.¹²

What kills them? The Norwegian Veterinary Institute breaks down the causes: infectious diseases accounted for 33% of mortalities at reporting sites, injuries — primarily from sea lice treatments — for 27%, unknown causes for 21%, and environmental conditions (jellyfish blooms, algal events, temperature stress) for 9%.¹²

The sea lice issue is particularly revealing. Sea lice are a naturally occurring parasite that thrives in dense salmon pens and can eat a fish alive. The industry’s main response has been mechanical or chemical delousing — treatments that are themselves stressful and injurious. Norwegian veterinary authorities record thousands of “delousing-related mortality events” every year, and the 27% injury-mortality figure above is largely a measure of how much the treatment hurts the fish.¹² It is a bleak cycle: crowding makes lice explode, delousing injures fish, injured fish get secondary infections, and the welfare downstream of open-net farming looks increasingly difficult to defend.

The Norwegian government has set a target to halve mortality by 2030. Meanwhile, British Columbia has mandated that all open-net salmon farms transition to closed-containment systems (land-based or floating closed tanks) — a policy driven by both wild salmon conservation and welfare concerns.¹³

Wild salmon welfare is a simpler, grimmer picture: the fish lives a natural life and then it is caught and killed. The “welfare” question shifts to fishing method: a troll-caught fish is landed individually and dispatched quickly; a gill-netted fish may struggle for hours. More on that in the sustainability section below.

Wild Pacific salmon are not one stock — they are five species (Chinook/King, Sockeye/Red, Coho/Silver, Pink, Chum/Keta) spread across thousands of rivers from California to Alaska to Russia’s Far East. Their status varies enormously by species, river system, and year.

The Pacific Salmon Foundation’s 2025 report found that roughly two-thirds of Pacific salmon populations are below their long-term average abundance.¹³ Fraser River Sockeye hit a record-low return of 474 000 fish in 2024 — though 2025 brought a dramatic reprieve with nearly 10 million returning, triple the forecast.¹³ Chinook (King) populations continue to decline broadly.¹³ Coho trends are mixed. Pink salmon are the resilience story — large returns in many regions, and survival has measurably improved in areas where salmon farms have been removed (notably British Columbia’s Broughton Archipelago).¹³

Alaskan salmon — the gold standard for wild — is managed under a constitutional mandate for sustainable yield. Alaska’s fisheries are considered among the best-managed in the world, and the majority of Alaskan salmon stocks are healthy. If your wild salmon says “Alaska,” you are buying from a well-regulated fishery.

Atlantic salmon is almost entirely farmed. Wild Atlantic salmon populations are severely depleted across their range and are not commercially fished at meaningful scale. Any “Atlantic salmon” you buy — unless explicitly labelled wild-caught from a specific, certified small-scale fishery — is farmed.

How wild salmon are caught matters for both sustainability and quality:

• Trolling (hook and line) is the most selective and highest-quality method. Small boats tow lines with lures; fish are caught individually, cleaned immediately, and iced. Primarily used for Chinook and Coho in Southeast Alaska. Low bycatch, minimal habitat damage.
• Gillnetting (drift or set nets) is widespread. Nets hang vertically in the water; salmon swim into them and are caught by their gills. Less selective — bycatch of non-target species and undersized fish is higher. Fish quality can be lower because the fish may be dead in the net for hours before retrieval.
• Purse seining encircles entire schools with a large net that is drawn closed at the bottom. Efficient for abundant species like Pink and Chum, but can stress and damage fish. Often used for salmon destined for canning.

If you care about quality and selectivity: troll-caught. If you care about price: purse-seined or gill-netted — but know the trade-off.

MSC (Marine Stewardship Council) certification is the most widely recognised sustainability label for wild fisheries. MSC-certified salmon fisheries meet standards for stock health, ecosystem impact, and management. Look for the blue MSC label.

ASC (Aquaculture Stewardship Council) is the farmed equivalent — it certifies farms that meet standards for environmental and social responsibility. ASC-certified farmed salmon is a meaningful step up from uncertified.

Organic farmed salmon exists under EU and private standards. Organic standards typically mandate lower stocking densities, restrictions on chemical treatments, and organic feed ingredients. The standards are real — but “organic” does not solve all the welfare concerns of open-net pens.