DNA barcoding for the identification of smoked fish products

Identification of fish fillets usually requires the application of a molecular tool because most of the morphological traits used in species identification are removed during the filleting process. Early molecular identification methods relied on protein electrophoresis that became recognized as an official method for fish fillet identification (AOAC, 1990; Tenge et al., 1993; Yearsley et al., 1999). Proteins are stable in fresh and frozen product, but are denatured and damaged by heat and salt processing, and are generally not suitable markers for species identification in smoked and canned fish products (Sotelo et al., 1992; Unlusayan et al., 2001). Furthermore, closely related fish species may share protein profiles, precluding specific identification of product (Bartlett & Davidson, 1991; Smith et al., 1996). The rapid developments in molecular biology have provided a range of tools for fish specimen and product identification. Most methods are based on amplification of a specific gene region and restriction enzyme digests of the amplified products and have been used to identify and distinguish closely related fish species. Examples include the cytochrome b gene in European flatfish (Cespedes et al., 1998), the 16S rRNA in salmonids (Carrera et al., 1999), the control region in swordfish (Hsieh et al., 2004) and the p53 nuclear gene in salmonids (Carrera et al., 2000). However, the methods