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a b s t r a c tThe morphological similarity among Sparidae species, which are characterized by a different market price, represents a serious problem for their trade and for stock management, since it encourages frauds for substitution. The most accredited morphological method for their identification is based on the dental-plate, but this approach is not simple and cannot be used for prepared products. When molecular methods are used the DNA degradation induced by cooking is the main drawback. In this work, we collected 314 reference tissues belonging to 75 Sparidae species and we produced a dataset of full (FDB) and mini-barcode (MDB) reference sequences starting from DNA extracted from fresh and ethanolpreserved tissues using universal primes. Moreover, some fresh samples were cooked. The FDB was successfully amplified in 91% (fresh), 50% (cooked) and 81% (ethanol-preserved) samples, while the amplification rates of the MDB were considerably higher in case of cooked (100%) and ethanol-preserved (94%) samples. The same primers were used for the amplification of the DNA obtained from 58 market samples (MS). All the DNA barcodes were compared with BOLD and GenBank using IDs and BLAST analysis. FDB was able to provide unambiguous species-level identifications for 53 (78%) and 44 (64.7%) reference samples analyzed on BOLD and GenBank, respectively. The Mini-DNA barcode (MDB) showed a lower discriminating power with 32 (45.7%) and 29 (41.4%) sequences unambiguously matched to a species on BOLD and GenBank. However, the MDB allowed to identify all the reference sequences as belonging to the Sparidae family. FDB and MDB showed a similar performance in analyzing the MS, allowing to highlight 21 (38%) mislabeled MS. Our study, while confirming the FDB as a reliable tool for fish authentication, proposes the MDB as a promising tool to recover molecular information in case of cooked products.

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The increasing rate of seafood frauds, especially in the case of highly priced species, highlights the need of verifying the identity of fish products. This paper describes the application of DNA barcoding to the identification of 52 products commercialized with the Chinese term 鳕 (Xue, Cod) in supermarkets (Nanjing and Shanghai) and in the online market. Considering the lack of harmonization around the definition of Cod, the mislabeling rate was assessed according to three increasingly stringent definitions: Cod meaning Gadiformes species; Cod meaning Gadus spp.; Due to the fact that the term "Cod" does not mean any specific species, since a qualifier ("Atlantic", "Pacific" or "Greenland") should be added to refer to Gadus morhua, G. macrocephalus or G. ogac, respectively. Results highlighted a very high mislabeling rate, which exceeded 60% even with the less stringent definition. Interestingly, only 42.3% of samples were Gadiformes, while the other were Perciformes, Pleuronectiformes or toxic Tetraodontiformes species. Economic, ecological and health issues arising from the misuse of the term Cod are discussed in the light of the leading role of China in the seafood worldwide industry and of the increased national consumption of marine species.Dear Editor, we would like to submit the following manuscript for possible publication: DNA barcoding reveals chaotic labeling and misrepresentation of Cod (鳕, Xue) products sold on the Chinese marketIn the era of food trade globalization, seafood products generally arrive to destination after changing hands several times. Thus, also considering that the residual morphological characteristics of processed seafood are inadequate for the identification, the substitution of high-quality species with less expensive ones become quite easy. In this context, the accurate labeling of seafood species plays an important role in protecting consumers and benefits the stocks conservation by combating the Illegal, Unreported and Unregulated (IUU) fishing.Seafood traceability has reached high standards level in Western countries, and in particular in the European Union. On the countrary, in China, where the incomes' growth has determined dramatic changes in the food consumption patterns towards premium marine species, such as Cod, most of the specific standards in force are non-mandatory and an official standardized system for seafood naming is still absent.Considering that Cod products are among the most investigated and mislabeled species on international markets and the chaos affecting the Chinese nomenclature system for seafood, in the present wotk DNA barcoding was applied for the identification of 52 products commercialized with the denomination 鳕 (Xue) (alone or in combination with other terms) in supermarkets in Nanjing and Shanghai, and on Chinese online retailers. To the best of our knowledge, this is the first work that takes into consideration seafood products from e-commerce. In particular, considering the lack of harmonization around the definition of Cod at the internatio...