Date of Award


Document Type

Open Access Thesis


Marine Science


College of Arts and Sciences

First Advisor

Joseph Quattro


The mislabeling of commercial fish products is a pervasive, worldwide problem. Most consumers of seafood are unaware this issue directly affects them and can even have negative impacts on their health. Mislabeling occurs when a product’s label is inconsistent with its content. Although mislabeling can be unintentional, deliberate mislabeling is a more common trend to increase profits and/or bypass fishing regulations - a form of economic fraud. Unfortunately, oversight, enforcement, and research are vastly insufficient in relation to the global scale of the problem. In order to add to the small knowledge base on European mislabeling rates, determine if overfished or harmful species have been sold, spread consumer awareness, and hold the industry accountable, tissue samples from everyday commercial products and restaurant servings labeled as Atlantic cod (bacalao in Spanish) were confirmed as containing cod via DNA sequence-based ‘barcoding’. Atlantic cod samples (n=546) were collected and characterized genetically from supermarkets, markets, and restaurants from eight cities (Madrid, Salamanca, Santiago de Compostela, Bilbao, Barcelona, Valencia, Granada, and Seville) throughout Spain. The DNA barcoding process used a universal PCR-based assay of the mitochondrial Cytochrome Oxidase-I (COI) and 16s locus using standard primer sequences and PCR conditions that are part of the Fish Barcode of Life initiative. Results indicate a 6.4% mislabeling rate (35/546) with no real statistical evidence of distinct geographic patterns of mislabeling. Common ling (Molva molva), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), and Alaskan pollock (Gadus chalocogrammus) were the most common substitutes, while Nile perch (Lates niloticus) and Vietnamese catfish (Pangasianodon hypopthalmus) were the most taxonomically dissimilar substitutes. These results are compared to other similar studies assaying fish products in the European Union and elsewhere.