JUL 14, 2015 10:06 AM PDT

What am I Eating? FDA Fights Seafood Fraud With DNA Sequencing

WRITTEN BY: Sarah Hertrich
Are you able to tell the difference between a piece of tilapia versus a piece of grouper? What about of piece of wild salmon versus a piece of farm raised salmon? In the United States more than 90% of seafood is imported. According to Oceana's 2013 national fraud seafood report, DNA testing found that one-third of their collected samples were mislabeled according to the United States Food and Drug Administration's (FDA) guidelines. The report also stated that approximately 30% of the shrimp sales were misrepresented.
Approximately one-third of the seafood in the United States is mislabeled according to a study performed by Oceana in 2013.
Seafood fraud is identified as the misrepresenting or mischaracterizing of seafood in the supply chain for economic gain. It can lead to illness caused by allergens or natural toxins due to mislabeling. Types of seafood fraud include seafood substitution, seafood short-weighting, and seafood mislabeling. Seafood substitution (aka "Bait and Switch") is the most well-known type of seafood fraud where, once fish is filleted and skinned, sellers will substitute a low-value species for a more expensive species because it is difficult for the consumer to identify. Much more common is short-weighting which occurs when processors misrepresent the weight of a seafood product through practices such as over glazing, soaking and breading. Seafood mislabeling occurs when other qualities of seafood are mislabeled in addition to the species name, such as the country of origin, to avoid regulations and fees or sneak illegally-caught fish into the supply chain.

When an illness occurs or seafood fraud is suspected, the FDA will perform identification tests to determine the species of the animal. Previously, the FDA used protein based tests were used for species identification of fish and crustaceans. Protein standards used for identification began to break down after about 10 years of storage. In 2007, a suspect case of puffer fish poisoning led the FDA to the Canadian Centre for DNA labeling at the University of Guelph because, at the time, none of the FDA's running labs were running the protein based tests. This led to the launch of the FDA Fish SCALE (Seafood Compliance and Labeling Enforcement) Project which won a 2015 Innovation Award. Because of this initiative, 9 of FDA's laboratories across the country now use DNA barcoding for species identification of fish and are currently in the process of developing protocols for DNA identification of crustaceans. DNA barcodes can be easily shared and sent via email. Another advantage of the DNA barcoding method is that even if a barcode is not available for a specific species, the method will match the sample to the most closely related species.

In order to avoid seafood fraud, experts suggest that your retailer questions about what you are purchasing. If they cannot answer your questions, you may not want to purchase from them. If the price is too good to be true, it probably is a sign that it is a mislabeled product. The four most common fish that are most likely to be mislabeled for species swap include tuna, snapper, salmon and grouper - always ask extra questions when buying these fish. Make sure you always purchase traceable seafood, which would be a commitment made by your retailer. When possible always purchase the whole fish and ask for the filets to be cut in the store. Be careful when ordering at sushi restaurants, which tend to have the highest rates of seafood fraud. Lastly, purchase your fish from larger chain supermarkets who are less likely to commit seafood fraud compared to smaller markets.

Sources: Food Safety News, Oceana, fishwatch.gov
About the Author
  • I am a postdoctoral researcher with interests in pre-harvest microbial food safety, nonthermal food processing technologies, zoonotic pathogens, and plant-microbe interactions. My current research projects involve the optimization of novel food processing technologies to reduce the number of foodborne pathogens on fresh produce. I am a food geek!
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