DNA barcode identification of commercial fish sold in Mexican markets

Abstract

The substitution of high-value fish species for those of lower value is common practice. Although numerous studies have addressed this issue, few have been conducted in Mexico. In this study, we sought to identify fresh fillets of fish, sharks, and rays using DNA barcodes. We analyzed material from "La Viga" in Mexico City, and other markets located on the Gulf and Caribbean coasts of Mexico. From 134 samples, we obtained sequences from 129, identified to 9 orders, 28 families, 38 genera, and 44 species. The most common species were Seriola dumerili, Pangasianodon hypophthalmus, Carcharhinus falciformis, Carcharhinus brevipinna, and Hypanus americanus. Pangasianodon hypophthalmus was most commonly used as a substitute for higher-value species. The substitution rate was 18% of the total. A review of the conservation status of the specimens identified against the IUNC list enabled us to establish that some species marketed in Mexico are threatened: Makaira nigricans, Lachnolaimus maximus, Hyporthodus flavolimbatus, and Isurus oxyrinchus are classified as vulnerable; Lopholatilus chamaeleonticeps and Sphyrna lewini are endangered; and the status of Hyporthodus nigritus is critical. These results will demonstrate to the Mexican authorities that DNA barcoding is a reliable tool for species identification, even when morphological identification is difficult or impossible.

A shot in the dark for conservation: Evidence of illegal commerce in endemic and threatened species of elasmobranch at a public fish market in southern Brazil

“…The Convention on International Trade of Endangered Species (CITES) of Wild Flora and Fauna is a major international agreement among governments that bans the international trade in threatened species, even so, there is evidence of high levels of trade in threatened species of both sharks and rays (Palmeira et al, 2013; Sarmiento‐Camacho, Valdez‐Moreno & Adamowicz, 2018; Hobbs et al, 2019; Rodrigues Filho et al, 2020), as well as systematic fraud, with higher‐priced species being substituted by cheaper ones (Carvalho et al, 2015; Harris, Rosado & Xavier, 2016; Staffen et al, 2017; Horreo et al, 2019; Mizrahi et al, 2019).…”

Multiple drivers behind mislabeling of fish from artisanal fisheries in La Paz, Mexico

“…When mislabeling involves a species that is illegally marketed with the intention of deceiving consumers, usually for financial gain, it is recognized as food fraud (Reily, 2018). A number of scientific and popular media reports have documented that seafood mislabeling is a widespread problem in national and international markets (Pardo, Jimenez & Perez-Villarreal, 2016;Warner et al, 2016), including Mexico (Sarmiento-Camacho & Valdez-Moreno, 2018;OCEANA, 2019). Besides economically defrauding consumers (Underwood, 2018), seafood mislabeling has multiple consequences, including indirectly diluting the signals of overexploitation of species throughout the commercial chain (Crona et al, 2016).…”

One‐step triplex high‐resolution melting (HRM) analysis for rapid identification of Atlantic cod (Gadus morhua), Alaska pollock (Gadus chalcogrammus) and haddock (Melanogrammus aeglefinus)

“…Financial incentive has been widely recognised as one of the greatest motivations for this illicit conduct. As an example, Sarmiento‐Camacho & Valdez‐Moreno (2018) revealed the substitution of striped catfish (30–40 $ per kg) for flounder (110 $ per kg) and sea catfish (40–50 $ per kg) in Mexico. While an unexpected exposure towards toxic species (Hsieh et al ., 2010), mercury contamination (Marko et al ., 2014), zoonotic seafood borne parasites (Williams et al ., 2020) and fish allergens (Triantafyllidis et al ., 2010) revealed also a health concern.…”