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Omega-3 fatty acid levels in wild and aquacultured fish: Is one better than the other?

By Bill Manci
June 28, 2020
https://thepaleodiet.imgix.net/images/Salmon-Farm.jpg?auto=compress%2Cformat&fit=clip&q=95&w=900 Photo: Shutterstock.com

The debate over the amount of omega-3 fatty acids in farmed, or aquacultured, fish has swirled for years. Media reports tend to disparage farmed fish as inferior to wild fish, which may lead you to wonder if you’re getting even adequate amounts of heart-healthy omega-3s you when you eat aquacultured fish.

As a 44-year veteran of both the commercial fishing and aquaculture sides of fisheries science and consulting, I’ve had a front-row seat to profound changes in both segments. Commercial fisheries have gone from “boundless” to “severely constrained.” Aquaculture and aquaponics have matured and become more sophisticated and are now two of the fastest growing segments of the world agricultural economy. [1]

I want to start by saying aquacultured fish are not perfect—not yet. Maybe someday that will be the case. In the meantime, aquaculture managers are working diligently on many fronts towards that goal. One of the questions they are addressing is the issue of contaminants in farmed and wild fish – which I hope to address in a future article. Many of you are rightfully concerned about this topic, and it deserves to be addressed.

Yet, there is a long list of reasons, which we have written about here previously, for why farmed fish, on balance, are better for you and our planet. The hyperbolic language in the media (e.g., farmed fish are “evil”) ignores many facts and a good deal of science. And it may be without merit when it comes to fat content—more specifically, omega-3 fatty acids.

Let’s take a closer look.

There is no doubt that aquaculture is positioning itself to dominate the seafood supply chain as we move into the future. In the coming years, more than half of the fish and seafood we consume will come from aquaculture farms rather than the oceans and lakes. [1] The supplies from the wild are finite. Relatively speaking, the same is not true for farmed species.

Given this fact, we benefit from a better understanding of the consequences of this seismic shift.

We have more information about farmed fish

With farmed species and the advent of third-party certification of farmed products, we have more information about the source of our seafood, and how it has been raised, if it comes from a hatchery or farm. True, not all farms are healthy; yet that is changing rapidly. We can determine how healthy it is with some accuracy, if need be, through a process known as traceability—following and documenting a fish and its treatment (i.e., feed, growth, physical handling, temperature during shipping, etc.) from its hatch to your table. On the other hand, with a fish that is sourced from some imprecise location in an ocean, sea, or lake, we have no idea about the level of exposure to pollutants, or its diet.

Equally important, with farmed fish, we can understand in a much more exact sense the nutritional qualities of our fish and seafood, because we know exactly what those fish and other seafood consumed during their lifetime. After all, you are what you eat, and that applies to fish as well as people.

And certainly, we will know exactly who to complain to if we are not satisfied with our seafood or if it leads to a human illness. There is, and will be, a rigorous chain of custody and handling for every piece we consume. Which means that there can be no passing of blame when it comes to human food safety.

This all means our fish and seafood are fully traceable. Such transparency is not possible when a fish is captured by human hands in the wild. We don’t know where it’s been, what it has eaten, how those food items have affected the quality of the fish’s flesh, or to what contaminants it may have been exposed. Those questions will be finally and completely put to rest as farmed seafood take over the marketplace.

Nutritional quality of farmed fish: percents vs quanitities

So, what about nutrition—and specifically the nutrition of farmed fish?

There appears to be general consensus in the literature about comparisons made between aquacultured and wild fish and their fat content. [2-4] Researchers agree that aquacultured fish contain a higher percentage of fat than wild fish. They also agree that the fats in wild fish contain higher levels of omega-3s as a percentage of total fats, when compared to aquacultured fish.

This is, unfortunately, where journalists tend to conclude that wild fish must be nutritionally superior because of their higher percentage of omega-3s.

But to paraphrase Ron Hardy in his 2003 article, people do not eat percentages, they eat portions. [2] And there is simply less fat in wild fish overall. Thus, while wild fish have a higher percentage of omega-3 fats within the fat portion of their flesh, they have less fat overall. So, as Harvard’s Julie Corliss pointed out, farmed fish tend to have higher levels of omega-3s overall per serving. [3]

As a counterweight to this, the higher total fat percentage in farmed fish means that someone eating a six-ounce serving of farmed Atlantic salmon consumes more omega-3s than a person eating a six-ounce portion of wild Atlantic salmon. The same can be said for rainbow trout (more omega-3s per serving). When it comes to Coho salmon and channel catfish, as compared to their wild counterparts, the amount of omega-3 fats consumed is virtually identical. [2]

In the end, not everyone focuses on the same nutritional details. Some of us take the stance that absolute amounts of omega-3 fatty acids are what really matter. Others prefer a more relative stance, with an emphasis on fat ratios.

So, if you agree with Dr. Hardy, our focus here should be on the serving size and the portions of omega-3 fats in the serving, not on the percentage of omega-3 fats. [5,6]

On the other hand, if you are inclined to focus on the ratio of omega-3s to other fats, then choosing wild options may be best for you. [7]

Ultimately, without compromise, you get your omega-3 fatty acids when you eat wild or farmed fish. Just be careful that the wild fish you eat are not contaminated with heavy metals or organic compounds. (To our point, that’s tough to know.) By comparison, the full traceability of aquacultured fare ensures and certifies wholesomeness in terms of omega-3 fats and the absence of contaminants.

Corliss summarizes the debate by saying, “Bottom line: Don’t stress too much about your salmon selection. Follow the American Heart Association’s advice to eat two servings of fish a week, letting affordability and availability guide your choices.” [3]

Final point: the importance of conservation

While my contribution here will not put this controversy to rest, I hope it gives you, as a reader, some comfort regarding your seafood choices. I have argued for a long time that we need to leave the wild fish to their own devices, and eat seafood that comes from farms, as we do with our terrestrial fare. When it comes to wild fish, I consider myself a conservationist. Wild fish are finite, and I prefer to see them conserved for future generations rather than wiped out. Rendering these fish extinct through commercial harvest in this era of human technology would be amazingly easy and rapid. Certainly, they do not exist simply to feed us.

Twenty years from now, our wild choices will be quite limited. Aquacultured seafood can help offset this decline. Rest assured the nutritional qualities of these products are on par with their wild counterparts and are only going to improve.

References

  1. FAO. 2018. FAO yearbook. Fishery and aquaculture statistics 2016. Food and Agriculture Organization of the United Nations. http://www.fao.org/3/i9942t/I9942T.pdf
  2. Hardy, R.W. 2003. Farmed fish and omega-3 fatty acids. Aquaculture Magazine 29(2):63-65.
  3. Corliss, J. 2015. Finding omega-3 fats in fish: farmed versus wild. Harvard Heart Letter, Harvard Medical School.
  4. Anonymous. 2019. Farmed salmon vs. wild salmon. Washington State Department of Health. https://www.health.harvard.edu/blog/finding-omega-3-fats-in-fish-farmed-versus-wild-201512238909 https://www.doh.wa.gov/CommunityandEnvironment/Food/Fish/FarmedSalmon
  5. Slee, E.L., et al., Low dietary fish-oil threshold for myocardial membrane n-3 PUFA enrichment independent of n-6 PUFA intake in rats. J Lipid Res, 2010. 51(7): p. 1841-8.
  6. 6) Lund, A.S., et al., N-3 polyunsaturated fatty acids, body fat and inflammation. Obes Facts, 2013. 6(4): p. 369-79.
  7. Simopoulos, A.P., An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients, 2016. 8(3): p. 128.

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