New certified reference material to counter seafood fraud

Seafood fraud – particularly the substitution or mislabelling – poses economic risks, potential health hazards and undermines efforts to conserve fish stocks. The high demand for seafood and the complexity of supply chains create incentives for dishonest practices, whereby cheaper species are presented as more valuable ones. EU legislation requires that production, processing and marketing of fishery or aquaculture goods be transparent, and national authorities routinely carry out inspections to enforce the relevant labelling rules.

While whole fish can be identified by morphological traits, filleted or processed fish require molecular methods such as DNA barcoding. This technique compares short, species specific regions of mitochondrial DNA with reference sequences to confirm species identity.

To aid control authorities, the JRC prepared EURM‑024 from a single swordfish fillet. The material was freeze‑dried and cryogenically milled to a fine powder. Bi‑directional Sanger sequencing verified that the two DNA‑barcode regions – the cytochrome b gene (cytb) and the cytochrome c oxidase subunit I gene (COI) – are unequivocally characteristic of Xiphias gladius. The material in EURM‑024 has been certified as being derived from Xiphias gladius, commonly known as swordfish. EURM‑024 is traceable to the corresponding sequences deposited in GenBank® (NCBI), FishTrace (EC) and the Barcode of Life Data System (BOLD).

Control laboratories can compare DNA sequences extracted from fish products with the ones from the certified reference material EURM-024, thereby improving the detection of mislabelled or substituted seafood and strengthening the EU’s fight against food fraud.