Wild vs. Farmed Salmon: Which Type of Salmon Is Healthier?

Wild-caught salmon vs. farmed salmon

Wild salmon is caught in natural environments such as oceans, rivers, and lakes.

But half of the salmon sold worldwide comes from fish farms, which use a process known as aquaculture to breed fish for human consumption (2).

According to the Food and Agriculture Organization of the United Nations, by 2030, fish farms will provide close to two-thirds of global food fish consumption (3).

Whereas wild salmon eat other organisms found in their natural environment, farmed salmon are given a processed, high fat, high protein diet that makes them larger (4).

Summary

The production of farmed salmon has increased dramatically. Farmed salmon have a completely different diet and environment than wild salmon.

Differences in nutritional value

Farmed salmon are fed processed fish feed, whereas wild salmon eat various invertebrates.

For this reason, the two types of salmon have different nutrient content.

The table below provides a good comparison. Clearly, there are some nutritional differences, most notably the fat content (5, 6).

Interestingly, wild salmon seems to have higher amounts of natural minerals, including calcium and iron.

Summary

Wild salmon often contains more minerals. Farmed salmon can be higher in fat.

Polyunsaturated fat content

The two main polyunsaturated fats are omega-3 and omega-6 fatty acids. These fatty acids play important roles in your body and are called essential fatty acids, or EFAs, because you need them in your diet (7).

However, it’s necessary to strike the right balance.

According to a 2018 published study omega-6’s do not increase inflammation. However, there is also evidence that high intake of omega-6 inhibits the anti-inflammatory effect of omega-3s. The study concluded this is a complicated matter and not properly understood (8).

While farmed salmon contains more fat than wild salmon, a large portion of that fat comes from omega-6 fatty acids (9).

For this reason, the omega-3 to omega 6 ratio is higher in farmed salmon than in wild.

Despite the differences, both farmed and wild salmon have a healthy omega-3 to omega-6 ratio, which should lead to a large improvement in omega-3 intake for most people — and is often recommended for that purpose.

In a small 4-week study in 2013, 19 people who ate farmed Atlantic salmon twice per week had a 50% increase in their blood levels of the omega-3 DHA (10).

Summary

Though farmed salmon is much higher in omega-6 fatty acids than wild salmon, the total is still too low to cause much concern.

Contaminants in farmed salmon

Both farmed and wild fish tend to ingest contaminants from the water they swim in and the food they eat (9).

In a 2017 study, both wild and farmed salmon have been shown to contain PCBs and dioxins, synthetic compounds once used in industrial and commercial processes (11).

Even though there is some evidence that PCBs and dioxins act as carcinogens in humans, the health benefits of both wild and farmed salmon outweigh the risks of the small amounts of synthetic compounds they may contain (11).

And according to the Washington State Department of Health, there are currently strict rules on contaminant levels in feed ingredients for farmed salmon. These changes have lowered contaminant levels in farmed fish in recent years (12).

Summary

Farmed salmon may contain more contaminants than wild salmon, but stricter rules on feed ingredients could be closing the gap. And while both types of salmon may contain contaminants, the health benefits of eating salmon outweigh the small risks.

Mercury and other trace metals

You’ve probably heard about the connection between mercury (a natural heavy metal that can cause health issues) and fish, but just how dangerous is it to eat salmon if you’re concerned about mercury levels?

According to a 2006 research review, although mercury is found in seafood, larger, longer-living predators (like sharks and swordfish) contain higher concentrations, while salmon has much lower concentrations (13, 14).

In fact, salmon is one of the “best” choices on the FDA’s list of “lower-mercury” seafood options (15).

As for other trace minerals, levels of arsenic may be higher in farmed salmon, but levels of cobalt, copper, and cadmium are higher in wild salmon. However, these metals are found in such low amounts in both varieties of salmon that they’re unlikely to be an issue (9).

If you are pregnant or breastfeeding and are worried about mercury, talk with your doctor or a dietitian about the right amount of seafood for your personal circumstances.

Summary

The levels of mercury and other trace metals found in wild and farmed salmon do not appear to be harmful when either type is eaten in moderation.

Antibiotics in farmed salmon

Due to the high density of fish in aquaculture, farmed fish are generally more susceptible than wild fish to infections and disease. To counter this problem, antibiotics are frequently added to fish feed (16).

Because antibiotic use in aquaculture is not always controlled, unregulated and irresponsible use of antibiotics has been a problem in the aquaculture industry (16).

Antibiotic use is not only an environmental problem but also a health concern for consumers. Ingesting traces of antibiotics over the long term may cause drug resistance, a hypersensitivity to antibiotics, and even the disruption of gut flora (17).

Many of the world’s largest producers of salmon, such as Norway and Canada, are considered to have effective regulatory frameworks. Case in point: From 2003 through 2011, some of Canada’s largest fish farms worked to drastically reduce their antibiotic use (18).

On the other hand, Chile — the world’s second largest producer of farmed salmon — was still experiencing problems due to excessive antibiotic use in 2018 (19).

In 2016, an estimated 530 grams of antibiotics were used for each ton of harvested salmon in Chile. For comparison, 99% of all salmon in Norway used has never been treated with any antibiotics (19, 20).

If you’re concerned about antibiotic resistance, you may want to consider buying only salmon that comes from the areas known for their decreased use of these medications.

Summary

Antibiotic use in fish farming is an environmental hazard as well as a potential health concern. Many countries strictly regulate antibiotic use, but it remains poorly regulated in others.

Is wild salmon worth the extra cost?

Farmed salmon has a lot of health benefits. The fish also tend to be larger than wild salmon and occasionally provide more omega-3s.

However, because of environmental and dietary differences, farmed salmon may contain more potentially harmful contaminants than wild salmon.

A big issue with wild salmon tends to be the cost: It can be expensive, and depending on your budget, it may be inconvenient to buy often or at all.

Buying a mix of farmed and wild salmon is a potential option if you’re looking to balance health benefits and cost. But if cost is a concern, buying farmed salmon is still recommended over avoiding salmon completely.

The bottom line

The American Heart Association recommends that most adults eat two servings of fatty fish, such as salmon, per week. This recommendation is due to the high level of omega-3s in fish like salmon and the health benefits that can come from optimal consumption (21).

While farmed salmon and wild-caught salmon are similar in terms of overall health benefits, farmed salmon may have more added antibiotics.

It’s also possible for both farmed and wild caught salmon to contain organic pollutants such as PCBs, as well as mercury.

If you’re trying to minimize your intake of certain contaminants, it may be a good idea to source your salmon from areas that have stricter guidelines or simply eat less of it.

However, given its high content of omega-3s, quality protein, and beneficial nutrients, any type of salmon is still a nutritious food choice.