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The effect of incorrect labeling of marlins on the Costa Rican fishing sector

COSTA RICA
Monday, April 14, 2025, 00:10 (GMT + 9)

Seafood Mislabeling in Costa Rica: Implications for Consumers, Economy, and Conservation

The mislabeling of seafood is a pervasive global issue with significant consequences for consumers, human health, and economic stability. A recent study conducted by the BIOMOL Molecular Biology Laboratory at LCI Veritas University in Costa Rica investigated the prevalence of mislabeling in billfish fillets (sailfish, swordfish, and marlins) sold in Costa Rican markets. Utilizing DNA barcoding techniques, researchers analyzed the cytochrome oxidase subunit I (COI) gene from 178 tissue samples collected from fish markets and vendors across all seven provinces of Costa Rica.

Juan Carlos Delgado-Carazo, coordinator of the BIOMOL laboratory, emphasized the lab's decade-long commitment to the responsible management of Costa Rica’s fisheries. “By applying high-confidence molecular tools, we aim to ensure the precise identification and origin of seafood products from our oceans, positively influencing their sustainable management,” he stated.

The DNA sequence analysis revealed high rates of correct identification for samples labeled as “sailfish” (93.44%) and “swordfish” (96.43%). Conversely, fish sold as “white marlin” and “pink marlin” exhibited the highest mislabeling rates, at 100% and 28.19%, respectively. Overall, the study found that 33.71% of the analyzed samples were mislabeled, raising concerns about consumer rights, fishery statistics, management policies, and conservation efforts.

The primary source of mislabeling was attributed to inconsistencies between common names used by the national fisheries authority and official global common names. Lead researcher Roy Saravia explained, “The removal of fins, heads, and guts during processing often leads to the loss of key morphological features, resulting in identification errors and subsequent mislabeling throughout the seafood supply chain.”

Despite Costa Rica's strong global reputation in marine conservation and efforts since 2012 to regulate seafood labeling for traceability, inaccurate labeling persists. This allows consumers to unknowingly purchase misidentified species.

“This research provides scientifically grounded insights into the seafood reaching consumers’ plates,” added Delgado-Carazo. “Our goal is to offer tools that enhance traceability, transparency, and sustainability within Costa Rica’s fishing value chain.”

The sample analysis employed DNA barcoding, a widely accepted method for detecting both accidental and fraudulent food mislabeling. Commercial names were compared against established scientific nomenclature. DNA barcoding was then used to verify if the genetic identity matched the label.

Samples were collected over a year (July 2022 to February 2023) from diverse geographic regions across Costa Rica to minimize the risk of resampling the same individuals. Each sample was labeled with its commercial name at the point of purchase, transported on ice, and processed at the BIOMOL laboratory. A small tissue fragment was extracted from each fillet, preserved in 99% alcohol, and stored at -20°C until DNA analysis.

The comparative analysis confirmed the overall 33.71% mislabeling rate. Sailfish and swordfish showed low mislabeling rates (6.56% and 3.57%, respectively).

Saravia highlighted the concerning finding that “approximately 10% of samples labeled as ‘marlin’ were actually sailfish. This mislabeling has significant implications for consumers, fisheries management, and species conservation.”

Delgado-Carazo concluded, “We advocate for the increased integration of DNA analysis into national seafood supply chains to ensure accurate labeling of wild-caught species consumed in Costa Rica. This will aid in detecting and preventing the illegal exploitation of vulnerable species.”

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