Study Reveals Over Half Of Fish Sold In Southern California Restaurants Are Mislabeled And Misleading

A recent investigation into species substitution and mislabeling of sushi, poke, and ceviche dishes sold in Orange County, CA restaurants has uncovered some startling evidence. The study was shared on Science Direct, and states that of 103 seafood samples identified, over 63.1% were mislabeled. 

Global aquatic food consumption has been increasing and reached a record high of 20.5 kg (45.19 lbs) in 2019. The following year, a recorded 3.8 billion kg (8377565.963 lbs) of seafood was captured in the U.S., valued at $4.8 billion. The increase can be traced to the health benefits of seafood, which are low in fat, high in protein, and filled with a wide range of essential nutrients and minerals. As it happens, most seafood sold for direct consumption is live, fresh, and chilled. In the U.S. respectively, sushi, poke, and ceviche are some of the most widely consumed raw, ready-to-eat (RTE) seafood dishes. 


Species substitution and mislabeling is common among raw, RTE seafood products due to their high price point and lack of morphological identifiers, which is the ability to identify based upon external characteristics.

Within the seafood industry, mislabeling occurs in various ways and can be intentional or accidental. Sometimes common names are incorrectly used, products are lost or substitutions are deliberately made, which all contribute to species mislabeling. Additionally, the global seafood supply chain is complex and labeling requirements can vary across countries.    



In order to maintain safety, cultural significance, conservation measures, and protect consumer interest, identifying seafood species substitution and mislabeling is important. Some seafood contains dangerous toxins which are unsafe to consume. For those who experience fish or shellfish allergies, it can be life threatening. Improper labeling can also potentially impact endangered species and conservation efforts. And lastly, why would anyone want to pay top dollar for the wrong type of seafood?

To assist in species identification, DNA barcoding is used. DNA barcoding is a sequencing-based method that differentiates species using a short, standardized genetic target. 

For the investigation into species substitution and mislabeling in Orange County, CA, 105 raw, RTE seafood products were collected. Determining if they were labeled correctly was established by comparing menu names, verbal declarations by restaurant staff, and the Food and Drug Administration (FDA) Seafood List. Of the 105 samples, 103 were identified by DNA barcoding, resulting in a species substitution detection rate of 23.3%, with 45.6% of samples having incorrect market names. An overall 63.1% of the samples had some form of mislabeling. 

hawaiian poke


When divided based upon product type, ceviche topped the list with a rate of 85.3%, poke came in next at 61.8% and sushi landed in third with a 42.9% mislabeling rate. Species substitution was more common for sushi while ceviche and poke were most often mislabeled.

In recent years, a study uncovered a mislabeling rate of 84% in Southern California’s sushi restaurants. Raw “white tuna” samples were found to actually be escolar, which contains a dangerous toxin called gempylotoxin. Specifically in Los Angeles, between 2012 and 2015, another study found that sushi products halibut, red snapper, yellowfin tuna and yellowtail were mislabeled at a rate of 47%. Beyond Southern California’s sushi problem, zero research was found on the mislabeling of U.S.-sold ceviche dishes or studies focused specifically on mislabeling of poke dishes. 

Simply put, many restaurants still have no clue which fish is being used for their products. Sometimes mislabeling is unintentional and other times it can be economically motivated. It’s uncertain how often it occurs due to the latter, but that, and also ensuring consumer safety, are why being able to identify species substitution and mislabeling is so important.