Seafood mislabeling in Greek market using DNA barcoding

Abstract

The mislabeling of seafood products is a worldwide observed issue even though labeling regulations have been established (either at local or European/International level). Various molecular methods have been developed for fish species identification and detection of fraud, with DNA barcoding being the most popular and accurate one. Here, we present the first large-scale analysis aimed at assessing the fish mislabeling rate in Greece, by amplifying a fragment of approximately 655bp of the COI gene in 285 fish products collected from multiple markets in Greece through a monitoring program of the Hellenic Food Authority (EFET) over a time span of 4 years. This study initiated in 2015 under a European Commission Recommendation on a coordinated control plan with a view to establishing the prevalence of fraudulent practices in the marketing of certain foods and was further supported by EFET for another 3 years in order to monitor the Greek market. Sequencing and species attribution was successful in 92.3% of the samples. In 12.9% of these (34 cases), discrepancies were detected between the declared and the identified species and therefore the products were characterized as mislabeled. This rate is low, compared to other studies in Greece and other regions of the Mediterranean Sea (e.g. Italy) and worldwide (e.g. Canada). On the other hand, it remains higher than the average global substitution rate of 8%, reported in a recent meta-analysis and the European rate of 6% detected during the EU coordinated control program in 2015. Flatfishes (order Pleuronectiformes) presented the highest mislabeling rate (28.3%) followed by gadiforms (order Gadiformes) with 13.7%. Although, in some cases the substitution can be unintentional due to similar morphological characteristics and geographical distribution among species, in 55.7% of the mislabeled samples the substituted species is of lower quality resulting inevitably also to an economic profit. Our results support the need for continuous and well-documented monitoring of Greek and European markets.