There’s a lot of controversy surrounding farmed vs wild-caught fish, but what are the actual differences between the two? Is the extra cost for wild-caught worth it, and is farmed fish a safe alternative?
Americans consistently eat less fish than recommended. Recommendations are to get two servings of fish per week, or 8 oz total. Fish, particularly fatty fish like salmon, are one of the best sources of omega-3 fatty acids, specifically EPA and DHA. These fatty acids are crucial for optimal brain and body functions. Fish are also a great source of high-quality protein, vitamins, and minerals. Despite their many health benefits, there’s been a lot of fear surrounding fish consumption, especially farmed fish consumption. So today, I’m going to unpack the actual differences between farmed and wild-caught fish and which I personally eat and recommend.
What is fish farming?
Contrary to popular belief, fish farming is not a new thing. In fact, people have been farming fish for centuries in order to increase its availability to consumers. Fish are farmed in a variety of different ways. Some are kept in the ocean in cages or nets. Others are contained in ponds, lakes, or ditches. Others still are farmed on land in large tanks. Where and how a fish is farmed can vary based on the country you live in and the species of fish.
How is farmed fish different from wild-caught fish?
Again, specific farming practices vary based on country. For the purposes of this post, I’m going to primarily cover farmed fish in the United States. It can also vary significantly based on species. I’ll be using generalizations in this post, unless I specifically indicate a species of fish that I’m comparing.
Throughout this post, we’ll cover some of the differences between wild-caught and farmed fish, and what influences, if any, these differences have on their safety and nutritional value. We’ll cover what they eat, antibiotic use, mercury content, sustainability, and affordability.
What they eat: wild vs farmed
Wild-caught fish have a variable diet based on what they’re able to find. In general, wild fish consume other fish and aquatic animals, including insects, and plants. Farmed fish, on the other hand, are often fed a commercial, fortified diet in the form of small pellets. These pellets are typically composed of ground fish, plant proteins, fish oils, vitamins, and minerals.
Does what fish are fed affect their nutritional quality?
Again, this is going to vary depending on species of fish. Let’s take a look at the nutritional differences between wild-caught and farmed salmon since salmon is one of the most consumed fish in the United States. To standardize, we’re going to compare 100 grams of wild-caught Atlantic salmon with 100 grams of farmed Atlantic salmon (this is about 3.5 ounces).
The differences:
- Calories: Farmed fish contains more calories by weight than wild-caught. Wild-caught salmon has about 140 calories per 100 grams while farmed has about 200 calories per 100 grams.
- Protein: There’s virtually no difference between the two when it comes to protein content.
- Fat: Farmed fish contains more total fat by weight than wild-caught. Wild-caught salmon has about 6 grams of fat per 100 grams while farmed has about 13 grams of fat per 100 grams of fish. Farmed fish also has higher omega-3 fatty acid content than wild-caught, though it also has higher omega-6 fatty acid content. The ratio of omega-3 to omega-6 fatty acids in both is good, though wild-caught has an even more favorable ratio.
- When it comes to the breakdown of these fatty acids farmed salmon contains more saturated fat, monounsaturated fat, and polyunsaturated fat by weight than wild-caught. Not sure what the significance of these fats is? Check out my blog posts on saturated fat and heart healthy fats.
- Carbohydrate: There’s no difference between the two when it comes to carbohydrate content.
- Minerals: There are only slight differences in the mineral content of farmed vs wild-caught salmon. And, in my professional opinion, the differences in mineral content between the two are so slight that they’ll end up being pretty negligible when it comes to your daily diet.
- Vitamins: Only slight variation exists between their water-soluble vitamin content (Vitamins B and C). Due to fortification of farmed fish feed (and probably higher fat content), farmed salmon has higher fat-soluble vitamin content (Vitamins A, D, E, and K) than wild-caught.
Disease and antibiotics: wild vs farmed
It should come as no surprise that when fish get sick in the wild they don’t receive antibiotics. Farmed fish, however, live in closer quarters than their wild counterparts. Unfortunately, this facilitates the spreading of disease. As a result, antibiotics are used both to treat disease and sometimes to prevent disease in farmed fish. Fortunately, the Food and Drug Administration (FDA) has parameters on antibiotic use in farmed fish. Fish farmed in the United States can only be given FDA-approved antibiotics. These antibiotics must be proven to be safe in the amounts found in fish at the time of human consumption.
While the antibiotics used in fish farming aren’t directly damaging to human health, concern still remains over antibiotic overuse in general and the rise in antibiotic-resistance as a result. New legislation in the United States, Canada, and Europe, among others, is working to balance the need for antibiotics in fish farming and its risk for overuse. Vaccination and changing the environment the fish live in are areas being explored to further reduce antibiotic-use in fish farming.
Mercury and other contaminants
With rising global pollution our oceans are not always a very clean place. Fish farmed in the oceans and wild-caught fish are at risk of mercury and other contamination as a result. Larger predatory fish (shark, tilefish, swordfish, etc) are at highest risk for mercury while smaller fish (tilapia, salmon, catfish, etc) contain the lowest mercury levels. Whether or not a fish is farmed or wild-caught isn’t predictive of its risk for contaminants. Rather, the specific type of fish and where it was caught are better indicators. The Monterey Bay Aquarium Sea Watch is a great resource if you’re concerned about contamination in your fish!
Sustainability and environmental impact
This is also a complicated topic when it comes to farmed vs wild-caught fish. For starters, it simply isn’t possible to get enough fish to meet everybody’s needs from the ocean. We’d deplete ocean reserves and irreparably damage wild fish populations. Hence why fish farming is so widespread. At the same time, neither wild-caught nor farmed fish are particularly friendly to the environment.
Different methods are used to catch fish in the wild, and some methods are more environmentally friendly than others. Bottom trawling, where weighted nets are pulled along the ocean floor can be particularly devastating. These nets can damage the ocean floor, destroying coral and trapping unwanted ocean animals in the process. Some unwanted fish that are caught along with the desired fish may simply be discarded. Overfishing is another issue that, while regulated in many countries, is not regulated worldwide.
Fish farms, on the other hand, can also have negative effects on the environment. Fish kept in close quarters in cages in the ocean can potentially spread disease to wild fish populations. Waste generated by fish farms is another possible concern that is better regulated in some countries than others.
Once again, it’s really about the specific type of fish and where/how it was caught. Just because a fish is wild-caught or farmed doesn’t give a good indication as to whether or not it’s sustainably raised. The Monterey Bay Aquarium Sea Watch can also help you find fish that are raised and caught in a sustainable way.
Affordability
In general, wild-caught fish is much more expensive than farmed. This can make it impractical for those on a tight budget. With current dietary guidelines recommending consumption of two servings of fish a week it’s important to also keep in mind the practical aspects of eating more fish with your current budget.
As a dietitian, what are your thoughts on farmed vs wild-caught fish?
In all honesty, I eat both. For me, the slight nutritional differences simply aren’t significant enough to convince me towards one or the other. Similarly for risk of contaminants and antibiotic use, there just isn’t enough hard data to sway me to one side or the other. We have a significant amount of research suggesting that fish consumption is beneficial for human health, and as such, I try to get at least one serving of fish per week (I’m working towards that recommended two, but it’s a work in progress!) regardless if it’s farmed or wild. Eating a variety of fish is a great way to mitigate your risk while still enjoying all the great benefits of fish consumption!
Do you eat farmed or wild-caught fish, and why? What questions do you still have about differences between the two?