DNA barcoding reveals a high incidence of fish species misrepresentation and substitution on the South African market Donna-Mareè Cawthorn a, ⁎, Harris Andrew Steinman b , R. Corli Witthuhn a a Department of Food Science, University of Stellenbosch, Private Bag X1, Matieland, 7602, South Africa b Food & Allergy Consulting & Testing Services (F.A.C.T.S), P.O. Box 565, Milnerton, 7435, South Africa abstract article info Article history: Received 11 April 2011 Accepted 8 November 2011 Keywords: DNA barcoding Fish species Identification Mislabelling Species authentication The mislabelling of fishery products has emerged as a serious problem on global markets, raising the need for the development of analytical tools for species authentication. DNA barcoding, based on the sequencing of a standardised region of the cytochrome c oxidase I (COI) gene, has received considerable attention as an ac- curate and broadly applicable tool for animal species identifications. The aim of this study was to investigate the utility of DNA barcoding for the identification of a variety of commercial fish in South Africa and, in so doing, to estimate the prevalence of species substitution and fraud prevailing on this market. A ca. 650 base pair (bp) region of the COI gene was sequenced from 248 fish samples collected from seafood whole- salers and retail outlets in South Africa, following which species identifications were made in the Barcode of Life Database (BOLD) and in GenBank. DNA barcoding was able to provide unambiguous species-level identifications for 235 of 248 (95%) samples analysed. Overall, 10 of 108 (9%) samples from wholesalers and 43 of 140 (31%) from retailers were identified as different species to the ones indicated at the point of sale. Although some cases of mislabelling were potentially unintentional due to misapplied market nomen- clature, a far greater proportion represented serious and seemingly deliberate acts of fraud for the sake of in- creased profits. This study has highlighted that the existing legislation pertaining to seafood marketing in South Africa is inadequate or poorly enforced and requires urgent revision. In the light of the results pre- sented here, DNA barcoding appears to hold great potential for fish authentication monitoring by both regu- latory bodies and industry, the utilisation of which could enhance transparency and fair trade on the domestic fisheries market. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction The world's marine fish stocks, which were considered just over a century ago to be ‘inexhaustible’ (Huxley, 2007), now face extreme fishing pressure as the insatiable human appetite for seafood contin- ually outpaces supply (Delgado, Wada, Rosegrant, Meijer, & Ahmed, 2003). Current data indicate that widespread overfishing has fully exploited, over-exploited or depleted up to 75% of global fish stocks (FAO, 2009) and has had deleterious effects on aquatic ecosystems (Pauly, Watson, & Alder, 2005; Worm, Barbier, & Beaumont, 2006). In a pertinent four-year study on 10 large marine ecosystems around the world, Worm, Hilborn, Baum, et al. (2009) reported that 63% of the assessed fish stocks were below desired levels and still require re- building, in spite of the numerous restrictions (annual harvest quotas, rights allocations, fishing gear modifications and seasonal or area clo- sures) that have been imposed to promote more sustainable fisheries management (Beddington, Agnew, & Clark, 2007; Brunner, Jones, Friel, & Bartley, 2009). During the last two decades, there has been a growing realisation that the incorporation of consumer behaviour into marine conserva- tion strategies will be required if the trends in fisheries declines are to be reversed (Kaiser & Edward-Jones, 2006). This realisation has led to a number of sustainable seafood awareness campaigns being initiated in many parts of the world, including the United Kingdom (UK), United States (US), Australia and Canada. The Southern African Sustainable Seafood Initiative (SASSI) was established in 2004 with similar aims of educating the local population on marine conservation issues and shifting consumer choices towards more sustainable sea- food species. Typically, such organisations compile seafood lists that rank species according to sustainability criteria (e.g. ‘best choice’ or ‘avoid’), the details of which are publicly disseminated via wallet cards, electronic databases and mobile phone applications (Roheim & Sutinen, 2006). A fundamental requirement for the success of all consumer awareness campaigns, as well as for fisheries management in general, is the accurate naming and labelling of fish products at the point of sale. Unfortunately, with escalating demand and globalisa- tion of seafood trade, the current market climate in many countries Food Research International 46 (2012) 30–40 ⁎ Corresponding author. Tel.: + 27 21 808 3578; fax: + 27 21 808 3510. E-mail address: 13946455@sun.ac.za (D.-M. Cawthorn). 0963-9969/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2011.11.011 Contents lists available at SciVerse ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres