Authentication and traceability of fish maw products from the market using DNA sequencing

• The genetic identification of the fish maws has been carried out.
• The applicability of four kinds of processed products was verified.
• 53.3% of the products were incorrectly labeled and 58.3% of “croaker” products were substituted with catfish or perch species.

Fish maws (dried swimbladders of fishes) are regarded as traditional luxurious delicacies, medicine and tonics, which have been recommended and consumed in Asia over many centuries. At the commercial level, they are ranked as different values based on species. However, fish maw species and the trade are still unknown and undocumented. The processing treatments make them difficult for species identification based on morphological characterization. In the present study, the genetic identification of the main commercialized species of fish maws has been carried out, based on the amplification of a fragment of mitochondrial 16S rRNA gene and subsequent BLAST analysis. The applicability of all kinds of processed products was verified, including dried, water soaked, salt fried and salt fried plus water soaked forms. The result indicated this method was applicable to all of them, showed that 53.3% of the products were incorrectly labeled and 58.3% of “croaker” products were substituted with catfish or perch species. Moreover, results indicated that besides traditional trade in Asia, the fish maw trade has been globally expanded to meet the growing demand of market. Therefore, this method can be useful in normative control of processed products, particularly in the authenticity of imported species, verifying the correct traceability in commercial trade, the correct labeling, and also for fisheries control of endangered species to conserve stocks biodiversity.