Authentication of red snapper (Lutjanus campechanus) fillets using a combination of real-time PCR and DNA barcoding

Abstract

Red snapper (Lutjanus campechanus) is a historically overfished and highly valued species that is commonly substituted with other fish, such as tilapia, rockfish, and other snapper species. The objective of this study was to assess the ability of real-time PCR to be used as a screening tool to rapidly test commercial fillets for the presence of red snapper, followed by species identification of negative samples with DNA barcoding. A total of 24 frozen, fresh, or thawed (previously frozen) fillets labeled as “red snapper” were tested with real-time PCR, along with 54 fillets from fish that are common substitutes for red snapper. Real-time PCR parameters were optimized to reduce cross-reactivity. All samples were also tested with DNA barcoding to confirm the identity of fish species. Among the 78 total samples, 3 were authenticated as red snapper with DNA barcoding and successfully detected with real-time PCR. An additional two samples were initially identified as red snapper with real-time PCR but confirmed negative with DNA barcoding, resulting in a false positive rate of 2.7%. Overall, 39.7% of all samples and 91.7% of “red snapper” samples were mislabeled. Red snapper was substituted with other snapper species, rockfish, sea bream, and mahi-mahi. These results illustrate the ability of real-time PCR to be used as a screening tool and the importance of species confirmation with DNA barcoding. Real-time PCR has the potential to be used as a rapid on-site screening tool for regulatory and industry officials to determine the authenticity of red snapper fillets.