There is an important debate over the safety of farmed salmon compared to wild salmon. Wild and farmed salmon differ in their environmental impacts and nutritional quality.

Salmon is a very popular fish, eaten by millions of people around the world. Due to its popularity, a lot of salmon now comes from fish farms rather than the wild.

This article compares wild salmon with farmed salmon and discusses the differences between them, including their environment and their diet.

Share on Pinterest
Morten Falch Sortland/Getty Images

Eating fatty fish, such as salmon every week has health benefits. The 2015–2020 American Dietary Guidelines recommend eating 8 ounces (oz) of seafood per week

Salmon is an excellent source of:

We explore the differences between farmed and wild salmon below.

1. Wild and farmed salmon living conditions

Farmed salmon are fish stocks kept in netted pens. The farmers control breeding, feed them, and provide medicine if needed. Sometimes, the pens are very crowded and the salmon cannot swim very far.

Overfishing of the world’s fish stocks has led to an increase in fish farming. Fish farming also keeps the price of fish lower.

Wild salmon live and breed in their native bodies of water. Humans have no control over their breeding, feeding, or health. Wild salmon swim long distances with no restriction.

Environmental and chemical contaminants affect wild salmon as well as farmed salmon.

2. Nutritional differences

Typically, wild salmon have fewer calories, saturated fat and vitamins A and D than farmed salmon but contain more protein.

In both wild and farmed salmon, the omega 3 content will vary depending on what the salmon eats.

According to a 2017 review, farmed salmon have higher levels of omega-6 fatty acids than wild salmon. Both farmed and wild salmon had comparable levels of an omega-3 acid called EPA, but farmed salmon had lower levels of the omega-3 acid DHA than wild salmon.

According to the Washington State Department of Health, “Farmed salmon fillets contain as many grams of omega-3 fatty acids as wild salmon because farmed salmon are fattier than wild salmon.”

Omega-3s are important for:

  • brain function
  • eyesight
  • sperm production
  • energy production
  • reduction of inflammation

Both farmed and wild salmon contain some compounds that are not good for the body. This is because salmon can absorb some chemicals and pollutants through their diet and their environment.

3. Differences in color

Wild and farmed salmon may differ in color due to their diet.

Wild salmon eat a lot of krill, crabs, and shrimp. These shellfish are high in a carotenoid called astaxanthin, which gives the salmon their pale pink-red color.

Sometimes wild salmon are white because of the way they process astaxanthin.

Astaxanthin is a potent antioxidant and anti-inflammatory that is essential for the general health of the fish. Fish farmers feed the salmon with pellet foods containing an artificial version of astaxanthin. The synthetic version of astaxanthin is not as strong as the natural version but is still beneficial.

Neither the natural and synthetic versions of astaxanthin are toxic to humans.

4. Persistent organic pollutants (POP)

According to an article in Diabetology & Metabolic Syndrome, POPs are human-made organic chemicals that take a long time to break down. POPs can build up in animal tissue. Fatty fish can contain high amounts of POPs.

POPs are also known as:

  • persistent, bio-accumulative and toxic (PBT)
  • toxic organic micropollutants (TOMP)

POPs include:

  • pesticides
  • pharmaceuticals
  • industrial chemicals

The same article states that POPs can increase the risk of type 2 diabetes in humans. POPs do this by affecting insulin. Insulin controls the body’s blood sugars.

Another study looking at POPs in indigenous communities where the people eat a lot of wild fish found an increase in type 2 diabetes.

POPs may also cause neurotoxicity. Neurotoxicity may increase the risk of Parkinson’s and Alzheimer’s disease.

A recent study found that wild Atlantic salmon contained higher levels of POPs than farmed salmon. This may be because their environment is uncontrolled and due to pollutants in the oceans.

A study looking at farmed Norwegian Atlantic salmon found levels of some POPs and pesticides were decreasing.

It appears that farmed salmon may contain fewer POPs than wild salmon. However, this is dependent on the type of fishmeal that farmed salmon eat. According to the Environmental Working Group (EWG), in 2003 farm-raised fish contained 5–10 times more of a POP called polychlorinated biphenyl (PCB) than wild salmon.

If choosing farmed salmon, it is beneficial to find a reputable, responsible, and sustainably-raised source.

5. Heavy metals

Heavy metals, such as mercury can create oxidative stress in the human body. Oxidative stress can cause damage to the cells, which can, in turn, cause a variety of health conditions.

Other heavy metals in fish include:

  • arsenic
  • cadmium
  • lead
  • mercury

One study found that wild Atlantic salmon contained more mercury than farmed Atlantic salmon.

All salmon have some level of mercury in their tissues. The omega-3s in salmon may help prevent the mercury causing damage.

6. Animal drugs

Fish farmers sometimes give the salmon antibiotics and animal drugs to keep them in good health. Some people have concerns that the use of antibiotics could increase human antibiotic resistance.

Wild salmon have less exposure to animal drugs than farmed salmon.

Choosing wild salmon is the safest option for people who are worried about ingesting animal drugs.

7. Environmental and animal welfare concerns

Other concerns involve the impact of farmed salmon on the local waterways. Wild salmon fit into their natural ecosystem and do not increase environmental pollution.

Fish farms can be a pollution risk, particularly if they are located in low current areas. This is because pollution caused by fish excrement and uneaten feed can enter the local ecosystem and pollute the habitats underneath the netted pens.

When located in high current areas, the waste is dispersed by the water.

Some fish farmers stock their farms with salmon that are not native to the area. This can cause problems if the fish escape.

Escaped salmon compete with local species for food and reproduction. Escaped salmon can also introduce disease and parasites.

The intensity of fish farming is also of concern. High-intensity fish farming for profit often leads to overcrowding, which can lead to increased disease.

From an ethical and environmental perspective, wild salmon is the best option when fished sustainably.

Farmed salmon contains more fat than wild salmon. The fat may be visible, and farmed salmon may look rounder in shape than wild salmon.

Wild salmon are seasonal and only available in the summer. They may have a wider variety of color as they have a different diet to farmed salmon.

Unfortunately, it is not always possible to tell the difference between wild and farmed salmon by reading the labels on the packages. The organization Oceana, found that 43 percent of the restaurants and shops they surveyed mislabeled salmon.

Judging whether farmed salmon is safe to eat is difficult. The level of contaminants in farmed salmon varies from location to location and depends on their diet.

Exposure to pollutants is still a risk for wild salmon, but studies may not always capture the level of risk.

Typically, wild salmon are nutritionally better, and sustainably-fished salmon have a lower impact on the environment.

Both wild and farmed salmon are safe to eat and are excellent sources of nutrients.