Endangered shark species traded as "cação" in São Paulo during the COVID-19 lockdown: DNA-barcoding a snapshot of products.

BACKGROUND: Elasmobranch populations are declining, predominantly driven by overfishing, and over a third of global sharks, rays, and chimeras are estimated to be threatened with extinction. In terms of trade, Brazil is ranked the eleventh-largest shark producer and the top importer of shark meat in the world. Research has shown that elasmobranchs are sold in Brazil under the name "cação" (a generic designation for cartilaginous fish) to overcome consumer resistance. METHODOLOGY AND RESULTS: This study used DNA barcoding to investigate the sale of sharks in the State of São Paulo during the COVID-19 lockdown. A total of 35 samples of "cação" were analysed, revealing six different shark species on sale, including Carcharhinus falciformis, Carcharhinus signatus, Carcharias taurus, Isurus oxyrinchus, and Isurus paucus, that are threatened with extinction according to the IUCN red list. This study demonstrates that vulnerable elasmobranchs are being commercialised under the label "cação" in the São Paulo State and Brazil. CONCLUSIONS: Comparison of shark products traded before and during the COVID-19 pandemic showed no significant difference, suggesting lockdown did not affect patterns of species commercialisation. Effective fisheries and sale monitoring, correct product labelling legislation and increased consumer awareness that "cação" is shark are needed for appropriate conservation and management of shark populations in Brazil.

Authentication of Frozen Chilean Blue Mussel (Mytilus chilensis) Commercialized in the Town of Osorno, Southern Chile, Using PCR-RFLP Analysis.

BACKGROUND: DNA-based technologies are reliable authentication methods for food products, enabling the detection of fraud, non-intentional substitution and control of mislabeling. The Chilean blue mussel (Mytilus chilensis) is a seafood commercialized in Chile under different formats, including packages of frozen specimens. In this format, the valves of mussels are removed during processing, thus impeding identification of the product by the consumer due to the lack of external characters. OBJECTIVE: To assess the authenticity of frozen Chilean blue mussels commercialized in southern Chile, particularly in the town of Osorno. METHODS: Six commercial brands of frozen Chilean blue mussel were authenticated by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method, based on the analysis of an 18S rDNA fragment. RESULTS: Restriction patterns obtained indicate that three brands (50%) proved to be 100% authentic, given that all specimens contained in the package were Chilean blue mussels. The other three brands (50%) contained specimens of other commercial mytilids, particularly the cholga mussel (Aulacomya ater), in a variable percentage (12.5-50%). CONCLUSION: This study based on the PCR-RFLP method provides evidence that Chilean blue mussels commercialized in a town located in southern Chile lack authenticity. This finding highlights the necessity for national producers to improve the production and/or packaging processes of this seafood. The authentication of commercial mussels is a matter of consumer interest and has been described in a recent patent on this issue that proposes an alternative methodology.