A comprehensive analysis of the mislabeling of Atlantic cod (Gadus morhua) products in Spain

Mislabeled commercial seafood products are pervasive, worldwide problems that threaten public health, undermine fisheries conservation efforts, and ultimately, lead to consumer financial loss. Although it can be unintentional, deliberately mislabeling of products is a more common trend used to increase profits and/or bypass fishing regulations, both of which are forms of fraud. Unfortunately, oversight, enforcement, and applied research remain insufficient relative to the global scale of the problem. To contribute to a currently small knowledge base on mislabeling rates in European markets, DNA sequence-based barcoding was applied to tissue samples from commercial products and restaurant offerings labeled as Atlantic cod (Gadus morhua) in Spain. Atlantic cod samples (n = 546) were collected from local markets, supermarkets, and restaurants from eight cities (Madrid, Salamanca, Santiago de Compostela, Bilbao, Barcelona, Valencia, Granada, and Seville). DNA barcoding used PCR-based assays of the mitochondrial cytochrome oxidase-I (COI) and 16S rRNA loci. A 6.2% mislabeling rate (34/546 samples) was discovered. There was no evidence of distinct geographic patterns of mislabeling, although tissue samples obtained from restaurants were more likely to be mislabeled than those sampled in markets and supermarkets. Processed forms of product (prepared, salted/smoked) were more likely to be mislabeled than fresh or frozen products. Common ling (Molva molva), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), and Alaskan pollock (Gadus chalcogrammus) were the most common substitutes, while Nile perch (Lates niloticus) and striped catfish (Pangasianodon hypophthalmus) were the most taxonomically dissimilar to Atlantic cod.