Saint Louis Survey on Seafood Mislabeling

2017-11-20T19:22:12-05:00June 2nd, 2017|News|0 Comments

Joan Stader, PhD

April 20, 2015


Purpose: To investigate the overall prevalence and type of mislabeling of seafood in restaurants and grocers in the Saint Louis Metropolitan area.

Study Design: This was a blind study which tested 84 samples from 45 retailers, including local and national grocers and restaurants in the Saint Louis metropolitan area over a period of 6 months in 2014. Seafood samples collected were code numbered and then submitted to an independent testing laboratory for identification of genus and species by DNA barcoding. The package label or menu listing of the seafood purchased was compared to the corresponding Market name of the FDA Seafood List (2014).

Results: Twenty-eight (28) of the 84 samples failed (23 by mislabeling and 5 by bacterial contamination). This represents a sample failure rate of 33%. Of the 45 retailers tested, 16 sold samples that failed, representing a 36% retailer failure rate. This report analyzes the details of this study.


Mislabeling of seafood is a notoriously well-known problem in various parts of the world including the United States. In recent years various organizations have tested and reported that restaurants, grocery stores and other fish retailers have been selling mislabeled seafood to unknowing consumers. Based on DNA barcoding, Florida’s Attorney General identified fraud in 17 of 24 restaurants tested in the Tampa Bay area in 2007 (Nohlgren, 2007). Successful prosecutions took place based on the results using approved test methods (DNA barcoding) by both state (Seafood Source 2014) and federal courts (Southern Shrimp Alliance, 2008; Southern Shrimp Alliance, 2011; Bales-Sherrod, 2011). Owing to its speed, reliability and robustness, DNA barcoding is considered the gold standard for seafood species identification and, hence, test results are admissible for prosecution in courts. For the same reason, DNA barcoding and DNA fingerprinting studies have been employed by various groups to understand the extent of mislabeling at the retail level on behalf of the consumer.

Numerous reports loudly voiced concern on the pernicious problem of seafood substitution and its ramifications on various stakeholders (i.e., fishers and local fishing communities, wholesalers, processors, regulatory agencies and governments, retailers and consumers). These reports include a 2006 investigative report by the Saint Petersburg Times in the Tampa Bay area that found mislabeled product in 54% of restaurants (Nohlgren & Tomalin, 2006); a 2008 study of grocery stores in Manhattan, NYC that revealed a 25% mislabeling rate (Schwartz, 2008); a 2011 Consumer Reports study in New York, New Jersey and Connecticut that found 19% mislabeled seafood in retail stores and restaurants (Consumer Reports, 2011); a 2011 Boston Globe investigative report of restaurants, grocery stores and seafood markets done in Boston that found 48% mislabeled seafood (Abelson & Daley, 2011).

In 2013, the non-profit group Oceana performed a study nationwide to measure the extent of the problem in the U.S. and found that about 33% of the fish purchased from seafood retailers in 21 states was mislabeled (Warner et al., 2013). The survey included 1,215 samples from a variety of retail establishments. There was a wide variation of seafood mislabeling among the cities tested, for example, 21% in Portland, 35% in Kansas City, 39% in New York, 18% in Boston [although another Boston study reported 48% (Abelson & Daley, 2011)], 26% in Washington DC, 38% in South Florida, 36% in Denver, 25% in Atlanta, 56% in Pittsburgh, 32% in Chicago, 49% in Austin/Houston, 38% in Northern California, 18% in Seattle, 52% in Southern California and 33% nationwide.

Drilling down deeper into the problem in 2014, a researcher at the University of Hawaii found that 15 percent of toothfish in ten states (of the US) properly labeled at the species level were mislabeled as to geographical origin (Murphy, 2014).

None of the well-known studies mentioned above examined the rate of seafood fraud in Saint Louis, MO; and we set out to obtain this information by gathering 84 samples from 45 retailers over a six-month period in the Saint Louis metropolitan area.


The study was conducted between February 28 and August 13, 2014. Six individuals collected all of the samples. Retailers were selected based on the desire to obtain representation from most parts of the Saint Louis metropolitan area, i.e., downtown, North Saint Louis County, Southern Illinois and West Saint Louis County. An attempt was made to sample all of the local grocery chains as well as the national grocery chains and “big box” stores. Single location grocery stores/fish shops were not sampled in the St. Louis metropolitan area. Casual, mid- and high-end restaurants were sampled, as well as sushi restaurants. Locations are marked in Figure 1.

Figure 1. Locations of retail establishments in the Saint Louis area tested in this study.

Grocery stores were chosen based on convenience for the sampler. Restaurants were usually chosen by looking at the menu on the internet to first see if there was a seafood choice. Sometimes more than one menu item was sampled from a particular establishment; species most often mislabeled (as reported in previous studies) were preferentially sampled.

Photos or pdf files of the menu were taken or downloaded. When orders were received in restaurants, photos of the food and the purchase receipt were taken so that a record was made of the menu item, date purchased and price. If the food was dine-in, a “doggie bag” was requested for the sample. Sometimes the food was ordered as “carry-out”. Samples were obtained using a sterile, single-use scalpel to cut a small piece of the fish. The sample was placed in a fresh, glass vial, labeled with a code number, and sent, on ice, to the DNA barcoding laboratory Applied Food technologies, Inc., Alachua, FL (AFT) by overnight delivery. The samples were analyzed by a DNA sequence alignment method (DNA barcoding). The DNA sequences of the samples were compared against a qualified taxonomically-validated database for fish.

AFT provided the genus and species of the sample as well as the FDA-Approved Market Name (FDA Seafood List, 2014). This information was compared to the labeling on the menu (for restaurants) or on the label affixed to the package (for grocery stores). In order to be consistent with the other studies, samples were considered mislabeled if AFT results and/or the advertised item did not match the FDA Market Name.

Results & Discussion

Eighty-four (84) seafood samples collected from the Saint Louis metropolitan area were tested, and 23 were found to be mislabeled while 5 were contaminated with bacteria. In the case of bacterial contamination, there is much more of the bacterial DNA present in the sample than the fish DNA, and therefore the results correspond to the genus of the bacteria present. In all 5 cases, it was a Pseudomonas species. All cases of bacterial contamination came from samples obtained from local grocery stores.

If the data are examined by retail category, then we see that samples taken from the national chains, which include both restaurants and grocery stores, have a failure rate close to the overall national percentage, but the number of national retailers failing the test was significantly lower than that of the local retailers (Table 1). The number of local grocers failing the test was a stunning 50%. However, most of the failures in the grocery stores were from contamination and all of the failures in the restaurants were from mislabeling. Moreover, we see that out of 12 samples taken from local grocery stores in Saint Louis, none were mislabeled (Table 2), but 5 were contaminated with bacteria.

Table 1. Mislabeling by Retail Category

*This number is not the sum of the other three categories because most samples fall into more than one category, i.e., some restaurants or grocery stores are also national chains.

Table 2. Mislabeling by Grocery Category

The mid- to high-end restaurants had the lowest percentage of mislabeling among various categories of restaurants (Table 3). Consistent with Oceana’s study (Warner et al., 2013) we found that sushi restaurants had the highest amount of mislabeling, with Oceana’s national percentage higher than that of Saint Louis’ (74% vs 64%). However, the percentage of sushi restaurants tested in Saint Louis who sold mislabeled fish was 67%.

Table 3. Mislabeling by Restaurant Category


*This number is not the sum of the other three categories because most samples fall into more than one category, i.e., some restaurants or grocery stores are also national chains.

Mislabeling by the type of fish

There were a total of 32 different species of fish sampled, and 11 of them were mislabeled at least once. The most heavily represented seafood species were salmon, tuna and cod, and this reflects the fact that they are most commonly offered for sale. Table 4 shows the data in descending order of mislabeling.

Table 4. Mislabeling by Advertised Name


The data gathered on seafood mislabeling in the Saint Louis metropolitan area produced results similar to the national results obtained in the Oceana study (Warner et al., 2013). Aside from looking at sushi restaurants, our study broke down the results by more categories of retailers, such as national chains, casual and mid-to high-end restaurants with informative results. Our study also paid attention to the issue of bacterial contamination, resulting in a significant difference between our results for grocery stores and the data reported by Oceana.

Bacterial Contamination

The presence of bacterial contamination prevents the detection of mislabeling. It is interesting that all of the bacterial contamination occurring in our study was found in grocery store samples. This result led us to ask whether the origin of the contamination was from our sampling process or the retailer. We used sterile scalpels to remove the samples and avoided touching the sample with our hands. Recognizing that there could still be human error on our part, we considered the fact that none of our other samples (79 of them) had bacterial contamination even though the same people handled the samples at our end. We also considered the fact that the grocery store samples were raw and therefore more likely to contain contamination than cooked samples. However, none of the sushi samples, which were also raw, were contaminated. We even returned to one of the grocery stores and bought more samples; again, they were contaminated. Therefore, we conclude that the grocery stores are failing to maintain a clean environment for their raw fish.

Retailers Mislabeling Seafood

It is important to specifically look at the numbers of retailers selling mislabeled seafood because the really big offenders can make the overall situation for retailers look a lot worse than it really is. For example, while the number of samples obtained from national chains is similar to the overall mislabeling rate (31%), only 17% of the national retailers sampled were found to be mislabeling their seafood.

The Salmon Label

Salmon can either originate from the Atlantic or the Pacific. The FDA market name “Salmon, Atlantic” is extremely ambiguous and the FDA should consider revising their policy. It is illegal to fish Atlantic salmon in US waters; therefore, if Atlantic salmon is on the menu, the fish is either imported, farm-raised or both. A menu item of “Chilean Salmon” is definitely farm-raised, because the species is not indigenous to Chilean waters. Norway is also home to a large fish aquaculture industry, and there is a good chance that the “Norwegian Salmon” on a menu is farm-raised. The consumer should be informed when farmed salmon is sold because it has lower nutritional value than wild-caught, and they are often tainted with antibiotics In fact, the Chilean salmon farms utilize 472 times as much antibiotic as Norway and these levels have been increasing every year (Wright, 2014). The FDA allows farmed salmon to be labeled “Atlantic Salmon” and does not require the seller to label them farm-raised.

FDA market names for Pacific Salmon are Sockeye, Chum, Keta, King, Chinook, Spring, Red, Blueback, Medium Red, Coho, Silver, Cherry, Pink and Humpback. “Alaskan” or “Wild Alaskan” salmon are not FDA market names, although the understanding would be that they describe a type of Pacific Salmon.

The Tuna Label

A broad range of tuna species can be labeled “Tuna”, but sushi restaurants will often label something “White Tuna” when it is, in fact, Escolar or Oilfish, a fish which contains a high level of toxins and has actually be banned in some countries. Other non-FDA market names for tuna on sushi menus are Tataki and Toro, but the use of these names is probably not meant to defraud consumers. The correct name for Yellowtail is “Amberjack,” so even though the seller probably does not intend to deceive the customer, it is not being sold by the legal FDA market name.

Outright Fraud

Some mislabeling is simply fraud. This would include inexpensive Tilapia being labeled “Red Snapper,” farmed salmon being labeled “Wild Caught Salmon,” Swai (Vietnamese catfish) labeled “Flounder,” and Rockfish labeled “Grouper”. We found examples of all of these in the Saint Louis metropolitan study. In addition to the other negative effects of mislabeling, significant health risks due to consumption of high levels of mercury tainted mislabeled seafood in 10 states in a recent survey (Marko et al., 2014) is an alarming signal impacting consumer protection.


Based on a limited number of samples, the rate of seafood mislabeling in the Saint Louis metropolitan area is fairly consistent with the rates found in other cities. The highest rate of mislabeling is found in sushi restaurants, followed by casual restaurants, mid- to high-end restaurants, and grocery stores. The unexpected finding is that local grocery stores frequently sell seafood with significant bacterial contamination.


I would like to thank David Fingerhut, David Fornelli, Charles Murphree, Jacqueline Murphree and Steven Wozniak for assistance in obtaining samples for this study and LeeAnn Applewhite, Kunapuli Madhusudhan and Dana Waganer for reviewing the draft manuscript.


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