Molecular identification of billfish (Osteichthyes, families Xiphiidae and Istiophoridae) products in Costa Rica as a tool to reduce mislabeling and fraudulent sales of fish

Commercial billfish (Osteichthyes, families Xiphiidae and Istiophoridae) products are frequently misidentified by the fishing industry due to common practices conducted as part of the commercialization process (e.g. fin and head removal), resulting in mislabeling. Molecular tools have been proposed to properly identify the species at the market stage. This research aims to identify the billfishes commercialized in Costa Rican markets using DNA barcoding. Sequences of the cytochrome oxidase subunit I (COI) region from 178 tissue samples were analyzed from markets and fish stores located throughout the seven provinces of Costa Rica. Sequence analyses showed that samples sold as “sailfish” and “swordfish” had the highest percent of correct identification (93.44% and 96.43% respectively). On the other hand, fish sold as “white marlin”, and “pink marlin” showed the highest percentages of mislabeling (100% and 28.19% respectively). The main source of mislabeling is inconsistencies with the use of common names by local fishing authorities and fishermen when compared to common names used by other countries in the region. Overall, mislabeling occurred in 33.71% of the samples analyzed, which can have important impacts not only on consumer rights but also on fisheries statistics, management policies, and conservation. • First mislabeling study of billfishes conducted in Costa Rica. • The total percentage of mislabeling detected was 33.71%. • “Sailfish” and “swordfish” presented low percentage of mislabeling. • “White marlin” and “pink marlin” presented high percentage of mislabeling.