Eureka! Institutional Repository

In the trade of many species, food processing usually causes the loss of any morphological diagnostic features of the species, enhancing the possibility of fraudulent substitution and mislabeling. Lack of morphological features due to food processing is common in elasmobranchs, as all external traits are discarded (e.g. skin, head and fins), and the body part is processed into filets. Such methods increase the chances of species substitution with cheaper alternatives or endangered species, leaving consumers unprotected from unfair or deceptive practices. DNA Barcoding has become the most commonly applied approach for detection of mislabeled seafood products and species substitution, because morphological identification is impossible, due to the processing of the fish. According to the Greek food and safety legislation requirements (Official Government Gazette 475/ Issue B’/27-3-2015, No. 1750/32219 under EU 1379/2013), only the Mustelus spp. products (Mustelus mustelus, M. punctulatus and M. asterias) can be sold under the commercial term "galeos". A total of 74 samples sold under the name galeos, were collected from 24 fishmongers and open markets located in four different cities of Greece (Athens, Thessaloniki, Kavala and Komotini), between March 2016 and May 2018. Genomic DNA was extracted from the sample tissue of fish, and the quantity and quality of the DNA were visualized on an agarose gel, with the use of ultraviolet radiation. Two different mtDNA genes (16S rRNA and COI) were selected for the analysis of each sample, and all PCR products were electrophorsed on agarose gel. The PCR products were purified and sequenced in an ABI automated analyzer. All produced sequences were checked and compared with those available in GenBank and BOLD databases, for species identification. Across the study, an extremely high level of mislabeling was identified (54.8%), as only 33 from 74 samples were classified to the Mustelus spp. species. It is worth mentioning that over half of products originate from species belonging to the IUCN red list (53.4%), and from species with prohibitions on landings by international and national legislation (57.6%). Τhe substitution of large-growing species, with little morphological resemblance to Mustelus spp., likely demonstrates deliberate substitution