When you eat tuna, there’s a good chance you’re not actually eating tuna. Instead, the majority of fish labeled “white tuna” may actually be escolar, a type of fish that can cause serious digestive effects, including oily anal leakage.
Oceana, the non-profit ocean protection group that revealed the findings, further found that nearly 60 percent of “tuna” sold at restaurants and grocery stores is another type of fish entirely – and the results fared worst for sushi restaurants. 
Love Sushi? Skip the So-Called “Tuna” (Ahi)
Oceana conducted DNA testing on more than 1,200 fish samples across the US and found that one-third were mislabeled. While red snapper had the highest mislabeling rates (87 percent of “red snapper” samples were not actually red snapper), tuna was a close second, with 59 percent mislabeled.
At sushi restaurants, however, 74 percent of fish samples were mislabeled. This included every single sushi restaurant from which samples were tested, even in major metropolitan areas like Chicago, Austin, New York and Washington DC.
According to Oceana’s 69-page report, in many cases, the mislabeled fish had been substituted for cheaper, less desirable and/or more readily available fish varieties. The results showed that: 
- Mislabeling was found in 27 of the 46 fish types tested (59 percent)
- 87 percent of fish sold as snapper was actually some other type of fish
- 59 percent of tuna was some other type of fish
- 84 percent of “white tuna” sold in sushi venues was actually escolar, a fish associated with acute and serious digestive effects if you eat just a couple of ounces
- Grouper, halibut, and red snapper were sometimes substituted with king mackerel and tilefish, two types of fish the FDA advises pregnant women and other sensitive groups to avoid due to dangerously high mercury content
Only 1 Percent of Imported Seafood Is Tested for Fraud
How are so many seafood retailers getting away with selling mislabeled fish? To put is simply, no one is minding the store
More than 90 percent of the seafood consumed in the US is imported, yet only 1 percent of imports are inspected for fraud, which may explain this clearly out-of-control situation. Oceana reported: 
“Our findings demonstrate that a comprehensive and transparent traceability system – one that tracks fish from boat to plate – must be established at the national level.
At the same time, increased inspection and testing of our seafood, specifically for mislabeling, and stronger federal and state enforcement of existing laws combatting fraud are needed to reverse these disturbing trends.
Our government has a responsibility to provide more information about the fish sold in the U.S., as seafood fraud harms not only consumers’ wallets, but also every honest vendor and fisherman cheated in the process – to say nothing of the health of our oceans.”
Another Reason to Avoid Tuna: It’s Typically Loaded With Mercury
Fish has always been the best source for the animal-based omega-3 fats EPA and DHA, but as levels of pollution have increased, this health treasure of a food has become less and less viable as a primary source of beneficial fats. This is particularly true for tuna, which tends to be a higher mercury fish.
Mercury in Tuna
One study from the U.S. Geological Survey found that ALL tuna tested contained fairly high amounts of mercury. The contamination may be even worse in restaurants, again confirming that eating restaurant tuna is a risky proposition.
Further, according to a separate study, toxicological testing revealed that tuna sold in restaurants actually contained HIGHER amounts of mercury than the store-bought variety.  The reason for this is because restaurants tend to favor certain species of tuna, such as bluefin akami and bigeye tuna, which had significantly higher levels of mercury than bluefin toro and yellowfin tuna.
Unfortunately, mercury tends to accumulate to a greater degree in muscle than in fat, rendering these highly prized, leaner species of tuna more susceptible to high contamination.
Another explanation is that restaurants tend to buy larger sized fish, which in turn contain larger concentrations of mercury due to their size. Remember, the larger the fish the longer it has lived, and the more time it has had to bioaccumulate toxins like mercury from the ocean.
Up to 80 Percent of Salmon May Also Be Mislabeled
It’s not only tuna and red snapper that is commonly mislabeled. In the video above, I interview Randy Hartnell, founder-president of Vital Choice Wild Seafood and Organics. He explains that as much as 70 to 80 percent of the fish marked “wild” salmon were actually farmed. This includes restaurants, where 90-95 percent of salmon is farmed, yet may be mis-listed on the menu as “wild.” The following tips can help you determine whether the salmon is authentic:
- Canned salmon labeled “Alaskan Salmon” is a good bet, as Alaskan salmon is not allowed to be farmed.
- In restaurants, mislabeled salmon will typically be described as “wild” but not “wild Alaskan.” This is because authentic “wild Alaskan” is easier to trace. The term “wild” is more nebulous and therefore more often misused. In many ways, it is very similar to the highly abused “natural” designation.
- Whether you’re in a grocery store or a restaurant, ask the seafood clerk or waiter where the fish is from. If it’s wild, they will have paid more for it, so they’re likely to understand the value proposition. Since it’s a selling point, they will know where it came from. If they don’t have an answer for you, it’s a red flag that it’s farmed, or worse… The US Food and Drug Administration is moving forward with approving genetically engineered salmon to be sold, and as you know, GE foods still do not need to be labeled in the US.
- Avoid Atlantic salmon, as all salmon labeled “Atlantic Salmon” currently comes from fish farms.
- Sockeye salmon cannot be farmed, so if you find sockeye salmon, it’s bound to be wild. You can tell sockeye salmon from other salmon by its color. It’s bright red as opposed to pink. The reason again for this bright red color is its superior astaxanthin content. Sockeye salmon has one of the highest concentrations of astaxanthin of any food.
Three Ways to Help Determine if Seafood Is Mislabeled
For the average diner, it can be difficult, if not nearly impossible, to determine if the tuna or red snapper in your sushi is actually what it’s claimed to be. That said, there are some ways to protect yourself against rampant seafood fraud: 
- Ask questions. Consumers should ask more questions, including what kind of fish it is, if it is wild or farm-raised, and where, when and how it was caught
- Check the price. If the price is too good to be true, it probably is, and you are likely purchasing a completely different species than what is on the label.
- Purchase the whole fish. When possible, purchase the whole fish, which makes it more difficult to swap one species for another.
Are You a Seafood Lover? Use These Tips to Stay Healthy
Aside from the fraud issue, which is clearly prevalent, most major waterways in the world are contaminated with mercury, heavy metals, and chemicals like dioxins, PCBs, and other agricultural chemicals that wind up in the environment. This is why, as a general rule, I no longer recommend getting your omega-3 requirements from fish, but rather from a high-quality, animal-based omega-3 supplement like krill oil. However, I do make two exceptions.
One is authentic, wild-caught Alaskan sockeye salmon, the nutritional benefits of which I believe still outweigh any potential contamination. The risk of sockeye accumulating high amounts of mercury and other toxins is reduced because of its short life cycle, which is only about three years. Additionally, bioaccumulation of toxins is also reduced by the fact that it doesn’t feed on other, already contaminated, fish.
Whenever I consume fish, I make sure to also take chlorella tablets. The chlorella is a potent mercury binder and if taken with the fish will help bind the mercury before you are able to absorb it, so it can be safely excreted in your stool.
The second exception is smaller fish with short lifecycles, which also tend to be better alternatives in terms of fat content, so it’s a win-win situation – lower contamination risk and higher nutritional value. A general guideline is that the closer to the bottom of the food chain the fish is, the less contamination it will have accumulated. So if you’re a seafood lover, try to choose most of your fish from this group, which includes:
If you insist on eating typical, store-bought fish and want to know more about the extent of your mercury exposure, I urge you to check out the online mercury calculator at GotMercury.org to get an idea of the risks.  Additionally, as mentioned above, you may want to consider taking a natural mercury chelator with any fish dinner. In addition to chlorella, this also includes zeolite (green clay) and fermented vegetables. Since larger fish tend to live longer and have the highest contamination levels, they should be avoided entirely. These include (please note this is not an exhaustive listing):
[1, 3] Oceana. (2014, February). Oceana Study Reveals Seafood Fraud Nationwide. Retrieved from http://oceana.org/en/news-media/publications/reports/oceana-study-reveals-seafood-fraud-nationwide
 Warner, K., PhD, Timme, W., Lowell, B., & Hirshfield, M., PhD. (2013, February). Oceana Study Reveals Seafood Fraud Nationwide. Retrieved from http://oceana.org/sites/default/files/reports/National_Seafood_Fraud_Testing_Results_FINAL.pdf
 Lowenstein, J. H., Burger, J., Jeitner, C. W., Amato, G., Kolokotronis, S. O., & Gochfeld, M. (2010, October 23). DNA barcodes reveal species-specific mercury levels in tuna sushi that pose a health risk to consumers. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed?term=%22Biology%2Bletters%22%5BJour%5D%2BAND%2B2010%2F04%2F21%5Bpdat%5D%2BAND%2Btuna&TransSchema=title&cmd=detailssearch
 Oceana. (n.d.). National Seafood Fraud Testing Results Highlights. Retrieved from http://oceana.org/sites/default/files/National_Seafood_Fraud_Testing_Results_Highlights_FINAL.pdf
 Turtle Island Restoration Network. (n.d.). Calculate Mercury Content in Fish & Seafood. Retrieved from https://seaturtles.org/programs/mercury/