Geographically widespread swordfish barcode stock identification: a case study of its application

• Published in: PloS one 2011-10, Vol.6 (10), p.e25516-e25516
• Main Authors: Pappalardo, Anna Maria, Guarino, Francesca, Reina, Simona, Messina, Angela, De Pinto, Vito
• Format: Article
• Language: English
• Subjects: Animals; Anopheles gambiae; Automatic Data Processing; Bar codes; Biochemistry; Biology; Case reports; Case studies; Cluster Analysis; Cytochrome; Cytochrome oxidase I; Data processing; Deoxyribonucleic acid; DNA; DNA barcoding; Environmental science; Evolution; Fish; Fisheries; Fishing; Food safety; Fraud; Gene sequencing; Geography; Geology; Haplotypes; Identification; International economic relations; Mitochondrial DNA; Molecular biology; Oceans; Oxidases; Pelagic zone; Perciformes - classification; Phylogenetics; Phylogeny; Phylogeography; Population genetics; Seafood; Seafoods; Species; Stocks; Studies; Swordfish; Taxonomy; Thunnus thynnus; Tuna; Xiphias gladius
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0025516

The swordfish (Xiphias gladius) is a cosmopolitan large pelagic fish inhabiting tempered and tropical waters and it is a target species for fisheries all around the world. The present study investigated the ability of COI barcoding to reliably identify swordfish and particularly specific stocks of this commercially important species. We applied the classical DNA barcoding technology, upon a 682 bp segment of COI, and compared swordfish sequences from different geographical sources (Atlantic, Indian Oceans and Mediterranean Sea). The sequences of the 5' hyper-variable fragment of the control region (5'dloop), were also used to validate the efficacy of COI as a stock-specific marker. This information was successfully applied to the discrimination of unknown samples from the market, detecting in some cases mislabeled seafood products. The NJ distance-based phenogram (K2P model) obtained with COI sequences allowed us to correlate the swordfish haplotypes to the different geographical stocks. Similar results were obtained with 5'dloop. Our preliminary data in swordfish Xiphias gladius confirm that Cytochrome Oxidase I can be proposed as an efficient species-specific marker that has also the potential to assign geographical provenance. This information might speed the samples analysis in commercial application of barcoding.