ITS1-rDNA-based methodology to identify world-wide hake species of the Genus Merluccius

Species-specific DNA-based tags are valuable tools for the management of both fisheries and commercial fish products. In this study, we have developed a two-step molecular tool to detect the presence of hake DNA (Merluccius spp.) and to identify the exact hake species present in an blind sample. The first test involves PCR amplification of an ITS1-rDNA fragment of 193 bp using nested primers that are interspecifically conserved in Merluccius spp. and Atlantic cod, Gadus morhua. The second test consists of the PCR amplification of a 602-659 bp DNA fragment spanning part of the ribosomal cluster 18S-ITS1-5.8S and digesting it with four restriction enzymes whose targets map at interspecifically nonconserved sites of the ITS1. Alternatively, the identification of hake species can be achieved by FINS or BLAST, using the nucleotide sequence of either the whole ITS1 sequence or its nested fragment of 193 bp. Because of their high reproducibility and ease of execution, these procedures allow for routine analysis and constitute high reliable tools for the rapid identification of 12 species of hake.