Meta-analyses of molecular seafood studies identify the global distribution of legal and illegal trade in CITES-regulated European eels

Mislabeled and ambiguous market names in invertebrate and finfish seafood conceal species of conservation concern in Calgary, Alberta, Canada

Background

The mislabeling of seafood, wherein a food product's marketed name does not match its contents, has the potential to mask species of conservation concern. Less discussed is the role of legally ambiguous market names, wherein a single name could be used to sell multiple species. Here we report the first study in Canada to examine mislabeling and ambiguous market names in both invertebrate (e.g., bivalve, cephalopod, shrimp) and finfish products.

Methods

A total of 109 invertebrate and 347 finfish products were sampled in Calgary between 2014 and 2020. Market names were documented from the label or equivalent and determined to be precise (the name could apply to only one species) or ambiguous (multiple species could be sold under that name). A region of the cytochrome c oxidase I gene was sequenced and compared to reference sequences from boldsystems.org. Samples were considered mislabeled if the species identified through DNA barcoding did not correspond to the market name, as determined through the Canadian Food Inspection Agency Fish List. Mislabeling was further differentiated between semantic mislabeling, wherein the market name was not found on the Fish List but the barcode identity was in line with what a consumer could reasonably have expected to have purchased; invalid market names, wherein the market name was so unusual that no legitimate inferences as to the product's identity could be made; and product substitution, wherein the DNA barcode identified the product as a species distinct from that associated with the market name. Invalid market names and product substitutions were used to provide conservative estimates of mislabeling. The global conservation status of the DNA-identified invertebrate or finfish was determined through the International Union for the Conservation of Nature Red List. A logistic regression was used to determine the relationship between precision and accuracy in predicting conservation status of the sampled species.

Results

There was no significant difference in mislabeling occurrence between invertebrates (33.9% total mislabeling occurrence, 20.2% product substitution) and finfish (32.3% total mislabeling occurrence, 21.3% product substitution/invalid market names). Product substitutions sometimes involved species of conservation concern, such as foods marketed as freshwater eel (Anguilla rostrata) that were determined through DNA barcoding to be European eel (Anguilla anguilla), or cuttlefish balls putatively identified as the Endangered threadfin porgy (Evynnis cardinalis). Product substitutions and ambiguous market names were significantly associated with the sale of species of conservation concern, but ambiguity was a more important predictor. Although preventing the mislabeling of seafoods can and must remain a priority in Canada, our work suggests that moving towards precise names for all seafood products will better support sustainable fisheries goals.

Determining the sustainability of legal wildlife trade

Exploitation of wildlife represents one of the greatest threats to species survival according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Whilst detrimental impacts of illegal trade are well recognised, legal trade is often equated to being sustainable despite the lack of evidence or data in the majority of cases. We review the sustainability of wildlife trade, the adequacy of tools, safeguards, and frameworks to understand and regulate trade, and identify gaps in data that undermine our ability to truly understand the sustainability of trade. We provide 183 examples showing unsustainable trade in a broad range of taxonomic groups. In most cases, neither illegal nor legal trade are supported by rigorous evidence of sustainability, with the lack of data on export levels and population monitoring data precluding true assessments of species or population-level impacts. We propose a more precautionary approach to wildlife trade and monitoring that requires those who profit from trade to provide proof of sustainability. We then identify four core areas that must be strengthened to achieve this goal: (1) rigorous data collection and analyses of populations; (2) linking trade quotas to IUCN and international accords; (3) improved databases and compliance of trade; and (4) enhanced understanding of trade bans, market forces, and species substitutions. Enacting these core areas in regulatory frameworks, including CITES, is essential to the continued survival of many threatened species. There are no winners from unsustainable collection and trade: without sustainable management not only will species or populations become extinct, but communities dependent upon these species will lose livelihoods.

Molecular identification of critically endangered European eels (Anguilla anguilla) in US retail outlets

The European eel (Anguilla anguilla) has declined by over 90% since the early 1980s and has been listed as critically endangered. Yet, despite strict export bans from the European Union, the European eel is still sold illegally in many countries. Efforts to monitor the trade of European eels have been primarily concentrated in Asian markets where concerningly high rates of European eel have been reported. Comparably fewer studies have assessed the identities of eel samples from the United States (US), despite the obvious implications for eel conservation. To address this knowledge gap, we purchased 137 eel products (134 freshwater eels and three saltwater eels) from grocers, sushi bars, and restaurants in nine states across the US from 2019 to 2021. Seven samples (5.2%) labeled as freshwater eels (or "unagi") were identified as European eels using a combination of mitochondrial (cytochrome b) and nuclear (18S rRNA) restriction digestion assays, a fast and inexpensive molecular tool for seafood identification that can identify hybrids between European eels (A. anguilla) and American eels (A. rostrata). No hybrids between European and American eels were found and all seven samples identified with restriction digestion as European eels were confirmed by sequencing of cytochrome b and 18S rRNA. Frequency of European eels in US markets did not significantly correlate with state or retail type. Although illegal eel exports are likely reaching US consumers, the frequency of European eel samples in this study of the US market is much lower than found in other non-European countries.

COIBar-RFLP Molecular Strategy Discriminates Species and Unveils Commercial Frauds in Fishery Products

The DNA analysis is the best approach to authenticate species in seafood products and to unveil frauds based on species substitution. In this study, a molecular strategy coupling Cytochrome Oxidase I (COI) DNA barcoding with the consolidated methodology of Restriction Fragment Length Polymorphisms (RFLPs), named COIBar-RFLP, was applied for searching pattern of restriction enzyme digestion, useful to discriminate seven different fish species (juveniles of Engraulis encrasicolus and Sardina pilchardus sold in Italy as “bianchetto” and Aphia minuta sold as “rossetto”; icefish Neosalanx tangkahkeii; European perch, Perca fluviatilis and the Nile Perch, Lates niloticus; striped catfish, Pangasianodon hypophthalmus). A total of 30 fresh and frozen samples were processed for DNA barcoding, analyzed against a barcode library of COI sequences retrieved from GenBank, and validated for COIBar–RFLP analysis. Cases of misdescription were detected: 3 samples labeled as “bianchetto” were substituted by N. tangkahkeii (2 samples) and A. minuta (1 sample); 3 samples labeled as “persico reale” (P. fluviatilis) were substituted by L. niloticus and P. hypophthalmus. All species were simultaneously discriminated through the restriction pattern obtained with MspI enzyme. The results highlighted that the COIBar-RFLP could be an effective tool to authenticate fish in seafood products by responding to the emerging interest in molecular identification technologies.