DNA barcoding reveals high substitution rate and mislabeling in croaker fillets (Sciaenidae) marketed in Brazil: The case of “pescada branca” (Cynoscion leiarchus and Plagioscion squamosissimus)

Abstract

The removal of morphological features during fish processing hinders identification to the species level, increasing the chances of species substitution and the mislabeling of marketed products. We used DNA barcoding to assess whether species substitutions occur in croaker (Sciaenidae) fillets labeled as “pescada branca” sold in the Brazilian Amazon, where two species are known under this vernacular name (Cynoscion leiarchus and Plagioscion squamosissimus). A 577-bp cytochrome C oxidase subunit I (COI) sequence was obtained from 137 fillets and compared with the sequences of whole Sciaenidae fish that were identified based on their morphology and the reference sequences of the BOLD and GenBank public databases. DNA barcoding was able to identify 90% of the samples analyzed to the species level, and the results showed a high rate of species substitution in the fillets labeled as “pescada branca”. The substitution rate was 100% if using the criterion that the fillets should be C. leiarchus and 76.6% if using the criterion that they should be P. squamosissimus. Additionally, the results show that “pescada branca” was replaced in most cases by species of lower commercial value, which clearly demonstrates economic fraud aimed at increased profits. Our data confirm that DNA barcoding is a sensitive and reliable tool that can be applied to authenticate processed fish.