Polymerase chain reaction-restriction fragment length polymorphism analysis for species identification of hairtail fish fillets from supermarkets in Japan

Hairtail fillets are marketed as both fresh and frozen forms in retail outlets within Japan. The present study was undertaken to develop a rapid and reliable method for identification of the hairtail species in commercial fillets. A total of 64 fillet samples, caught from various localities within Japan and purchased from various supermarkets, were analyzed. Polymerase chain reaction (PCR) amplification of a portion of the mitochondrial DNA encoding 16S ribosomal RNA gene and subsequent restriction digestion of the amplified products, using VspI endonuclease, generated different restriction patterns indicating two different species of hairtails in the fillet samples. The results indicated that the commercial hairtail fillets, labeled and marketed as 'Tachiuo' in Japan, were comprised of two species of hairtails with Trichiurus japonicus (commonly called Tachiuo) accounting for 47% and Trichiurus sp. 2 (commonly called Tenjikutachi) accounting for 53% of the analyzed samples. This simple and inexpensive PCR-restriction fragment length polymorphism analysis can be routinely applied to determine species composition of hairtails in commercial fillets.