Fish and Chips

These groups work to protect the brand names and quality of their respective products or businesses; monitor issues and legislation that may impact the industry, including fraud and other illegal activities; and work with government agencies and other organizations to promote the health and viability of their industry. The NFI also created the Better Seafood Board to help its members combat such seafood fraud problems as transshipping to avoid antidumping duties, short-weighting, and species substitution. As a condition of membership, all members of NFI have pledged to abide by fair and lawful business practices.

Regulatory organizations like the Directorate-General for Maritime Affairs and Fisheries of the European Commission (EC) have established labeling laws for fish and aquaculture products requiring traceability information such as species identification, origin of fish, and production method. The EC adopted a regulation to prevent, deter, and eliminate illegal, unreported, and unregulated fishing, which went into effect on January 1, 2010. This regulation will have a significant impact on countries that trade in fisheries products with, but are not members of, the European Union (EU), because all fish materials imported into the EU after that date must be accompanied by catch certificates.

Seafood substitution is prohibited in the United States according to the Federal Food Drug and Cosmetic Act Section 403(b): Misbranded Food. Federal, state, and local agencies play a role in detecting and preventing seafood fraud throughout the supply chain. In general, federal agencies inspect seafood processors, distributors, importers, and imported seafood products. States also inspect seafood processors, either through contracts with the United States Department of Agriculture or under their own authority, and states and local governments inspect and regulate retail establishments such as restaurants and supermarkets.

Lab-on-a-chip technology is one of the newer tools for detecting mislabeled seafood products.

Tools for Detection

Determination of seafood species has traditionally been based on species-specific electrophoretic, chromatographic, or immunological characteristics of proteins.¹ Analyses have been done using isoelectric focusing, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, capillary electrophoresis (CE), high-performance liquid chromatography, and immunoassay systems.

These methods are generally reliable for use with fresh or frozen tissue, but intense heat processing or drying can destroy the biochemical properties and structural integrity of proteins, often making protein analysis impractical. Enzyme-linked immunosorbent assay, which may be useful even in heat-sterilized products, has been used for the identification of several fish species. Immunoassays can be ineffective at differentiating closely related species, however, and they require the development of an antibody against the specific protein of interest.

The use of DNA-based methods for species detection offers a number of advantages over protein-based methods, including increased ease of use, specificity, sensitivity, and reliable performance with highly processed samples. DNA molecules are more thermostable than proteins during processing, and DNA fragments suitable for analysis can still be recovered following sterilization. As a result, numerous genetic methods are currently being used to identify certain fish and seafood species.

Some DNA-based methods employ polymerase chain reaction in combination with restriction fragment length polymorphism (PCR-RFLP), while others use sequencing through DNA barcoding or forensically informative nucleotide sequencing (FINS), amplified fragment length polymorphism, or single-strand conformation polymorphism. These techniques have been applied to the identification of numerous species of seafood, including gadoids, flatfish, salmonids, scombroids, sardines and anchovies, eels, mollusks, and many more.

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Schematic diagram of the Agilent Technologies lab-on-a-chip technology used to perform fish species identification utilizing polymerase chain reaction-restriction fragment length polymorphism.

Detecting Species-Specific Variations

A popular method for DNA-based seafood identification is PCR-RFLP, which is based on variations in the lengths of particular restriction fragments generated from specific regions of the genome. Species-specific variations in the lengths of the fragments are analyzed by PCR amplification of specific DNA regions. The amplicons are then digested with restriction enzymes, and the lengths of the digested fragments are determined by gel electrophoresis, resulting in species-specific restriction profiles.