Using DNA barcoding to track seafood mislabeling in Los Angeles restaurants

Abstract

Seafood mislabeling is common in both domestic and international markets. Studies on seafood fraud often report high rates of mislabeling (e.g., >70%), but these studies have been limited to a single sampling year, which means it is difficult to assess the impact of stricter governmental truth-in-labeling regulations. We used DNA barcoding to assess seafood labeling in 26 sushi restaurants in Los Angeles over 4 years. Seafood from 3 high-end grocery stores were also sampled (n = 16) in 2014. We ordered 9 common sushi fish from menus, preserved tissue samples in 95% ethanol, extracted the genomic DNA, amplified and sequenced a portion of the mtDNA COI gene, and identified the resulting sequence to known fish sequences from the National Center for Biotechnology Information nucleotide database. We compared DNA results with the U.S. Food and Drug Administration (FDA) list of acceptable market names and retail names. We considered sushi-sample labels that were inconsistent with FDA names mislabeled. Sushi restaurants had a consistently high percentage of mislabeling (47%; 151 of 323) from 2012 to 2015, yet mislabeling was not homogenous across species. Halibut, red snapper, yellowfin tuna, and yellowtail had consistently high (<77%) occurrences of mislabeling on menus, whereas mislabeling of salmon and mackerel were typically low (>15%). All sampled sushi restaurants had at least one case of mislabeling. Mislabeling of sushi-grade fish from high-end grocery stores was also identified in red snapper, yellowfin tuna, and yellowtail, but at a slightly lower frequency (42%) than sushi restaurants. Despite increased regulatory measures and media attention, we found seafood mislabeling continues to be prevalent.

Mislabeling Obscures the Sale of Threatened and Sustainable Fishes

“…Another recent genetic study (Willette et al . ) corroborates this finding, and life‐history‐based measures of vulnerability were not conclusive in either direction (−0.03 [−0.28, 0.21] FishBase vulnerability score, where negative values indicate less vulnerable true species than labeled species; S4). Thus, our finding that mislabeling does not consistently replace taxa of low conservation concern with those of greater conservation concern appears robust to limitations of using the conservation metric of IUCN status.…”

The Value of the Tree of Life

“…Every sushi restaurant sampled from Chicago, New York, and Washington, DC, had at least one mislabeled fish (Stern et al, 2017; see http://www.smithsonianmag.com/science-nature/how-dna-testing-cantell-you-what-type-of-fish-youre-really-eating-378207/). In Los Angeles sushi restaurants studied over a three-year period, researchers found that 47% of the fish samples were incorrectly labeled (Willette et al, 2017).…”

Rethinking solutions to seafood fraud

“…Research on seafood mislabeling in restaurants follows a common pattern: publication of results, immediate media coverage and calls for action, decreased media attention over time, and subsequent publication of another study with renewed calls for action. For example, three recent DNA-based surveys of Los Angeles (California) restaurants found mislabeling rates of up to 52% (Warner et al 2012;Khaksar et al 2015;Willette et al 2017), generating substantial media coverage. While helping to inform proposed legislation on counteracting seafood fraud in the US (Upton 2015), including the implementation of new programs targeted at foreign imports (eg NOAA Seafood Import Monitoring Program 2016), these and other studies have unfortunately done little to reduce seafood mislabeling rates in restaurants in Los Angeles or elsewhere in North America, Europe, and Asia (Warner et al 2013;Nagalakshmi et al 2016;Christiansen et al 2018).…”

“…Second, in cooperation with seafood restaurant owners, the Project is using blind sampling and DNA barcoding to monitor fish that wholesalers sell to restaurants. As part of undergraduate laboratory classes, students from Loyola Marymount University, California State University Los Angeles, and the University of California Los Angeles are conducting monthly sampling at local sushi restaurants, followed by DNA barcoding as described in Willette et al (2017). Aggregate data are then reported to Project stakeholders in an annual workshop and shared with the public through Another critical factor in ensuring positive outcomes was engaging industry in the process of improving regulatory requirements.…”