Is that fish you’re eating what label said?

University of Hawaiʻi
swai fish
The most common mislabeled fish was swai.

Scientists at the University of Hawaiʻi at Mānoa School of Life Sciences have reported that 21% of the seafood sold in the greater Honolulu area is mislabeled.

The most common mislabeled fish was swai, sold as a more expensive fish under a variety of names. The study also uncovered the sale of two endangered species, sold under generic market names that obscure the true identities of the fish.

The new research by Michael Wallstrom, a graduate student in zoology; Kevin Morris, an undergraduate student in geography; Peter Marko, an associate professor in the School of Life Sciences and head of The Marko Lab; and Laurie Carlson, regional director of Slow Food Oʻahu, was published in Forensic Science International: Reports.

Seafood mislabeling has been documented worldwide. According to researchers, most mislabeled seafood involves less expensive species sold under the names of more expensive species, suggesting substitutions are motivated by profit. These species substitutions also hinder environmentally-driven consumer choice, allowing overfished and threatened species to reach the marketplace.

Seafood mislabeling in Honolulu

Despite the importance of seafood in local culture and in the tourist-driven economy of the state, no studies of seafood label accuracy have been conducted in Hawaiʻi. The new study used mitochondrial DNA sequencing or “barcoding” from 75 samples of fish to detect seafood mislabeling in restaurants, grocery stores and sushi bars in the greater Honolulu area. Marko said that 21% “is a relatively low rate for a major metropolitan area,” lower than the national rate (33%) found in the largest study from the U.S. mainland by Oceana.

The most common mislabeled fish was swai (Pangasianodon hypophthalmus, also known as Pangasius, Sutchi and Tra), which is being sold as red snapper, sea bass and mahi-mahi. Swai is a species similar in flavor and texture to catfish that is commonly cultivated in Vietnam.

Many names considered acceptable by the U.S. Food and Drug Administration (FDA) lack the specificity to provide consumers with sufficient information about what exactly they are actually eating. For example, according to the FDA, 16 different species may be legally labeled as sea bass. Hawaiʻi consumers are familiar with the fact that both Bigeye and Yellowfin tuna are typically sold under the Hawaiian name ʻahi. Although Bigeye can be more expensive, overlap in the quality of these two species often results in either being sold as simply ʻahi.

Critically endangered fish

European eel swimming in water
European eel (Photo credit: J. Renoult)

The new study from UH Mānoa also found that one fish sold as ʻahi was actually a southern bluefin tuna, an overfished species considered “critically endangered” by the International Union for Conservation of Nature (IUCN) and rare in the Hawaiʻi marketplace. Similarly, two fish sold under the generic sushi label unagi turned out to be the IUCN critically endangered European eel (Anguilla anguilla), also listed by the Convention on International Trade in Endangered Species.

Unagi is the Japanese name for freshwater eels, a group of fish that spends its adult life in freshwater, but migrates to the ocean to reproduce. While American eels (A. rostrata) also face intense fishing pressure, the European Union has banned all European eel exports in an effort to curtail illegal harvesting and facilitate recovery of the species; nevertheless, juveniles are caught by EU and by non-EU countries and are illegally exported to Asia where they are raised in aquaculture facilities and then imported into the U.S. as “freshwater eel.”

When imported into the U.S., the country of origin labeling requires only the last country of processing to be provided on seafood packaging in the U.S., not where the seafood was originally caught.

“Given how complex global seafood supply chains are, it would be much easier for consumers to make informed choices if both the Latin species name and the actual country of origin had to be provided by the seller,” Marko said.

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