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Chilean researchers have carried out a survey of misdescription and fraud in the sale of swordfish (Xiphias gladius) in Santiago's fish and open-air markets.  DNA barcoding was used for taxonomic identification of swordfish and shark species. Forty seven headless, gutted and fin-removed samples sold as swordfish were collected from the fish and open-air markets. Most of the samples (91.5%) were correctly described as swordfish, but 6.4% were identified as porbeagle shark (Lamna nasus) and 2.1% as shortfin mako (Isurus oxyrinchus). No substitution was found in supermarket samples. These shark species are classified as vulnerable and endangered (IUCN), respectively, and listed in Appendix II (CITES). The authors have recommended stronger fish labelling rules and enforcement in Chile to improve shark conservation.

Read the abstract here

The Caribbean Red Snapper (Pargo) Lutjanus purpureus is the most economically important snapper in Brazil, which is sold, among other forms, as frozen fillets. 142 samples were collected between March 2013 to October 2014 from supermarkets in the State of Pará, North Brazil, which were processed by a single supplier. These were analysed using a DNA method, which sequenced a 600-bp fragment corresponding to the barcode portion of COI gene  to identify the fillets, with the aid of sequences from the public and control databases. Only L. purpureus and L. campechanus can be denominated “Pargo” in Brazil, but the results found that 22% of the samples were Rhomboplites aurorubens, a snapper with low commercial value in the country, revealing commercial fraud.

  Read the full paper at: Caribbean red snapper substitution

Indian researchers have developed a protocol based on PCR-RFLP (restriction fragment length polymorphism) by treating a 515 bp fragment in the highly polymorphic mitochondrial D-loop region with a single enzyme Tsp5091 to give fragment fingerprints to identify 9 species of snapper. Individual species could be differentiated by 3–5 major bands. Very closely related species like L. fulvus and L. fulviflamma gave similar patterns due to high (94%) identity, while the other seven species were clearly differentiated. The method worked with frozen, cooked and fried fish, and was tested on samples of snapper purchased in a local market.              Read the abstract at: snapper identification                               

There has been a large increase in Sushi restaurants in recent years around the world, but in Europe and North America in particular. Studies have indicated that fish species substitution is widespread in the US restaurants, so a study was commissioned into English Sushi restaurants to see if similar levels were occurring. 115 samples were collected from 31 restaurants from 6 English cities, and analysed using DNA sequencing of cytochromeoxidase. Overall substitution levels were around 10%, which is much lower than that found in US restaurants and also indicates better inspections and enforcement regimes in England.   

Read the full study at:  https://peerj.com/articles/1891/