Why should you not eat salmon anymore? Unpacking the risks in your diet

October 24, 2025 •

3 min read

According to a 2004 study published in Science, farmed salmon contained concentrations of polychlorinated biphenyls (PCBs) that were, on average, eight times higher than in wild salmon. This revelation and other pressing concerns have led many to question: Why should you not eat salmon anymore?

Quick Summary

Concerns surrounding salmon consumption stem from contaminants like PCBs, antibiotic misuse in farming, and significant environmental damage from aquaculture. This article explores the nuanced differences between farmed and wild salmon and reveals potential health risks.

Key Points

Farmed Salmon Risks: Contains higher concentrations of persistent organic pollutants (PCBs) and is often treated with antibiotics and pesticides to manage disease and parasites.
Environmental Damage: Open-net salmon farming contributes to water pollution, spreads disease to wild populations, and threatens ecosystems with waste and escaped fish.
Wild Salmon Isn't Perfect: While a cleaner option, wild salmon populations are endangered by habitat destruction, climate change, and face risk from farmed fish diseases.
Lower Nutrients in Some Farmed Fish: Some studies suggest farmed salmon may offer fewer beneficial nutrients like omega-3s and minerals compared to wild salmon.
Healthy Alternatives Exist: Numerous alternatives like sardines, mackerel, or plant-based sources can provide omega-3s and protein without the associated risks.
Moderate Intake Advised: The potential risk from contaminants means that moderation is key, especially when sourcing farmed salmon from regions with less stringent regulations.

Farmed vs. Wild Salmon: The Hidden Differences

A critical look at the differences between farmed and wild salmon reveals stark contrasts in potential health and environmental risks. While both have their nutritional merits, how they are raised and sourced significantly impacts what ends up on your plate.

The Problem with Persistent Organic Pollutants (POPs)

Polychlorinated biphenyls (PCBs) are oily, synthetic industrial chemicals that have been banned in many countries, but they persist in the environment and accumulate in fatty tissue. For farmed salmon, PCBs often enter the food chain through fish feed.

Studies indicate higher PCB concentrations in farmed salmon compared to wild salmon.
Older research raised concerns about potential health risks from PCBs in farmed salmon, linking them to reproductive and neurological issues and classifying them as probable human carcinogens.
Despite some claims of reduced contamination in farmed fish feed, independent tests have found concerning levels of various persistent pollutants.

The Environmental Toll of Open-Net Salmon Farming

Open-net salmon farming, a common global practice, involves raising fish in crowded pens in coastal waters, releasing significant waste directly into the ocean. This practice has several negative environmental impacts:

Fish waste can lead to eutrophication, harming marine life.
High stocking densities contribute to the spread of diseases and parasites like sea lice, which can infect wild salmon.
The use of antibiotics and pesticides to control diseases and parasites contributes to antibiotic resistance and harms other marine species.
Escaped farmed fish can interbreed with wild populations, potentially weakening their genetic makeup.

A Closer Look at Nutritional Trade-Offs

While salmon is known for omega-3 fatty acids, the nutritional content can vary. Farmed salmon often have higher total fat due to being raised for market weight, but not necessarily a higher percentage of beneficial omega-3s. Some studies suggest farmed salmon fat may contain a lower percentage of omega-3s than wild salmon. Farmed salmon production can also result in a net loss of certain nutrients in the smaller fish used for feed. The presence of fat-soluble contaminants in farmed salmon can offset the perceived benefits of its fat content.

The State of Wild Salmon

Choosing wild salmon also presents challenges, as these populations are impacted by various human and natural factors. These include overfishing and habitat destruction. Development, logging, and dams destroy crucial spawning grounds and migratory routes. Climate change also negatively affects wild salmon survival. Wild salmon can accumulate contaminants, though typically at lower levels than farmed fish.

Healthy Alternatives to Salmon

For those seeking nutrient-rich options without the concerns associated with some salmon, several alternatives are available.

Fish and Seafood Alternatives

Sardines and anchovies are small, low-mercury, omega-3 rich, and often sustainably sourced.
Atlantic mackerel is another low-mercury, high omega-3 fish.
Responsibly farmed steelhead trout can be a sustainable choice.
Arctic Char is a relative of salmon often raised in environmentally friendly systems.
Cod or Haddock are lean protein sources, though lower in omega-3s.

Plant-Based Alternatives

Walnuts and chia seeds are good plant-based sources of ALA omega-3s.
Seaweed and algae are direct sources of omega-3s that fish consume.
Flaxseed oil is a potent source of plant-based omega-3s.

Conclusion: Making Conscious Choices

The decision regarding salmon consumption involves balancing nutritional benefits against documented health and environmental concerns, particularly those linked to industrial farming. Sustainably wild-caught varieties, especially from well-managed fisheries like Alaska, are generally preferred for those who choose to eat salmon. However, exploring sustainable alternatives is a viable way to maintain a nutritious diet while minimizing potential risks and supporting healthier marine ecosystems.

For further reading on sustainable seafood choices, consider exploring the Monterey Bay Aquarium's Seafood Watch recommendations.

Frequently Asked Questions

No, salmon, whether farmed or wild, is generally considered a low-mercury fish. Larger, longer-lived predator fish like shark and swordfish contain much higher mercury concentrations.

PCBs are banned industrial chemicals that accumulate in the fatty tissues of animals. In farmed salmon, PCBs primarily come from the fishmeal and fish oil used in their feed, which is sourced from smaller fish that have accumulated the pollutants.

While generally considered a better option than farmed salmon, wild salmon can still contain environmental contaminants like PCBs and mercury, though often at lower levels. Moreover, wild populations face significant threats from habitat loss and climate change.

Open-net salmon farms release concentrated waste and chemicals directly into the ocean. This can pollute the seabed, alter local biodiversity, and contribute to eutrophication, harming the marine environment.

Heavy antibiotic use in densely populated salmon farms contributes to the spread of antibiotic-resistant bacteria. While some countries have reduced usage, others still use high amounts, which can pose environmental and long-term public health risks.

When farmed salmon escape, they can compete with wild fish for food and habitat. More critically, they can spread diseases and parasites, like sea lice, to vulnerable wild stocks and interbreed, potentially weakening the genetics of wild populations.

Excellent alternatives include small, oily fish like sardines, mackerel, and anchovies, which are lower in contaminants. For omega-3s, you can also consider plant-based sources like walnuts, chia seeds, and seaweed.