Untangling the cephalopod market: Authentication of seafood products in Greece with DNA-barcoding

Abstract

Cephalopod products are very popular in Greece and are considered a delicacy. However, heavy processing and marketing practices interfere with visual inspection and impede morphological identification, allowing species substitution. Mislabeling of seafood products remains a worldwide issue despite existing labeling regulations at local and European level. For the detection of fraudulent products, a variety of identification methods have been developed, however DNA barcoding remains the most favored. This study aims to investigate the cephalopod species sold in the country's seafood market and assess their mislabeling rates. Two mitochondrial genes, the cytochrome c oxidase subunit I (COI) and the 16S ribosomal RNA (16S), were selected for the analyses. A total of 156 samples were collected from fishmongers, markets, and restaurants across four cities. Identification was successful in 93.58% of the samples and 59 discrepancies (40.41%) between the label and the identified species were recorded. However, in some cases, substitution might have been unintentional, caused by negligence, lack of detailed information on the label, and the overall low awareness of the legislation by retailers. High mislabeling rates were estimated, especially when compared against the average global substitution rate in seafood products but align with those reported by studies on cephalopod products. This study is the first to investigate mislabeling rates in cephalopod commodities in Greece. With the aim of a transparent seafood trade, our results highlight the need for monitoring of all seafood products available in the country's market.