Detection and identification of marine fish mislabeling in Guangzhou's supermarkets and sushi restaurants using DNA barcoding

In this study, DNA barcoding was applied to identify the distinct species of fish products in Guangzhou supermarkets and sushi restaurants in order to confirm whether products were correctly labeled. Samples were analyzed using mitochondrial cytochrome C oxidase subunit I (CO I) gene as the target. Our results showed that the CO I gene of all 139 samples examined was successfully amplified by PCR. When sequenced, 30 samples (21.58%) were mislabeled as the wrong species, 11 samples had insufficient information provided on the label to determine if the labeling was correct (7.91%), and four samples failed sequencing (2.88%). We also found that the use of proper labels for fish products in sushi restaurants was higher than that in supermarkets. As a simple, rapid, and efficient technology, DNA barcoding can be widely used for species identification of fish products. Our work shows that regulation of the labeling of fish products, as we evaluated in Guangzhou and other markets in China, is needed on a global scale.