Counterfeit fish: the extent of seafood mislabeling in the United States


Khaksar, R., Carlson, T., Schaffner, D., Ghorashi, M., Best, D., Jandhyala, S., Traverso, J., Smini, S., (2015). Unmasking seafood mislabeling in U.S. markets: DNA barcoding as a unique technology for food authentication and quality control. Food Control. 56:71-76. doi: 10.1016/j.foodcont.2015.03.007

Figure 1: Sushi (Credit: Alexandra Guerson)
Figure 1: How much of your sushi board is exactly what you order? (Credit: Alexandra Guerson)


Seafood mislabeling is the intentional or unintentional practice of selling seafood under the wrong name.  Motivation for intentional mislabeling usually involves substituting a low value species for a high value species to increase profits, or to meet market demand. When mislabeling occurs, it not only cheats consumers economically, but it can also affect the amount of mercury unwillingly consumed and create mistrust for consumers who may decrease their seafood consumption.  On the supply side, it can also affect food security and biodiversity conservation as fishery management and conservation science relies on species specific data.  For the fisherperson, inappropriately labeled seafood may dilute the market, driving down prices for those who work hard on the water to provide a particular seafood species.  Last week, we learned that around 40% of the time, the Maryland blue crab cake you order is actually made from a different species of crab from the Indo-Paific!  Media coverage of general mislabeling studies in the U.S. has popularized the 2013 finding that one-third of U.S. seafood is mislabeled.  What is the mislabeling situation now?  Is it still as bad as we think, even worse, or better?  Tracing and identifying seafood back to its scientific species name based on physical traits can be challenging after seafood has been filleted, grilled, or otherwise processed.  Therefore, Khaksar et al., harnessed the power of DNA barcoding, a widely used tool in food control, to study mislabeling in three US areas where consumers are more conscious about high-quality, authentic seafood: Austin, TX, New York City, NY and San Francisco Bay Area, CA.


The study

Two hundred and twenty-eight seafood samples were collected over 4 months (June – September, 2014) from three areas: Austin, New York City and San Francisco Bay Area.  The majority (179/228) of samples were from popular sushi restaurants in all three areas, and 49/228 were specifically from wholesalers and retailers in the San Francisco bay area.  DNA from these menu items were extracted, the region of interest (mitochondrial cytochrome oxidase which is particularly useful for identifying fish and seafood samples by species) was bookended with primers and amplified or copied by orders of magnitude in quantity through polymerase chain reaction.  The copied portions of DNA were then sequenced (the order of nucleotides A,C,G,T was determined with 95% success) and matched to a database.


Results & Significance

Turns out, mislabeling is not as bad as we thought (at least in Austin, New York City and San Francisco Bay Area).  Mislabeling of seafood sampled in this study was 16.3% with little variation between the three areas, a significant drop from the 33% mislabeling rate found in the 2013 study.  This drop may be due to increased consumer awareness and demand for transparency and traceability. However, if we assume this data is representative for the U.S., this 16.3% mislabeling rate represents $16.5 billion USD of the fish market—still a sizeable amount.

Interestingly, within San Francisco, the rate of mislabeling was significantly higher (15.8%) compared with retailers and wholesalers at (2.2%).  This result may be due to brand competitiveness with consumer transparency.  It may also indicate that restaurants fall victim to mislabeling as well since mislabeling can happen at multiple points throughout the supply chain.  Red snapper was the most mislabeled seafood item (100%!) as it was substituted in favour of tilapia, or red seabream.  Other commonly mislabeled species were sea bass, fluke, Spanish mackerel, bass, black mussel, canned tuna and salmon, see Figure 1.  One challenge for the consumer is that restaurants do not often provide detailed information about their product on their menus.  For example, there are two main groups of salmon: Atlantic (one species) and Pacific (several species including chum, coho, chinook, sockeye and pink).  Atlantic salmon is mostly farmed and less expensive.  However, 24/25 samples tested were found to be Atlantic salmon.  Another challenge is that under the Food and Drug Administration, a single fish species can legally be called several different names throughout the supply chain, and on the other hand, several different fish species can legally be sold under the same name (i.e. 64 distinct fish species can legally be sold as “grouper”).

A selection of findings from Khaskar et al., 2015 of advertised name, expected scientific species, number of falsely advertised samples and substituted species.
Figure 1: A selection of findings from Khaskar et al., 2015 of advertised name, expected scientific species, number of falsely advertised samples and substituted species.

We are not able to say for sure that the findings in Austin, New York City and San Francisco give us an accurate understanding of the mislabeling climate of the U.S. as a whole and the world.  Therefore, there is a continuing need for mislabeling studies to get a true sense of the issue.  Seeing as over 90% of seafood in the U.S. is imported and only 0.001% of seafood imports is tested for fraud, there is a lot of work to do.  However, the creation of the Regulatory Fish Encyclopedia by the FDA is a critical step, and there is no doubt that consumers and restaurants will grow ever more demanding for more transparency in the seafood supply chain.

Do you ask before you buy?  Let us know in the comments!

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