Amanda M. Naaum

Interlaboratory evaluation of a real-time multiplex polymerase chain reaction method for identification of salmon and trout species in commercial products.

This interlaboratory study evaluated a real-time multiplex polymerase chain reaction (PCR) method for identification of salmon and trout species in a range of commercial products in North America. Eighty salmon and trout products were tested with this method by three independent laboratories. Samples were collected in the United States and Canada, and only the collecting institution was aware of the species declaration. Following analysis with real-time PCR, all three laboratories were able to identify species in 79 of the 80 products, with 100% agreement on species assignment. A low level of fraud was detected, with only four products (5%) found to be substituted or mixtures of two species. The results for two of the fraudulent products were confirmed with alternate methods, but the other two products were heavily processed and could not be verified with methods other than real-time PCR. Overall, the results of this study show the usefulness and versatility of this real-time PCR method for the identification of commercial salmon and trout species.

Seafood Mislabeling Incidence and Impacts

With seafood consumption at a global high, the economic incentive for species substitution is evident. The global seafood supply chain is sufficiently complicated as to present numerous points of entry for mislabeled goods. The incidence of seafood mislabeling is beginning to be understood by means of market surveys, often employing DNA testing over the past decade, that have been conducted on every continent. These tests continue to improve in both efficacy and size and have identified that the seafood industry is highly susceptible to problematic labeling, with an average of around 25% of samples from all studies identified as mislabeled. This chapter details the use of market surveys for identifying mislabeling, trends in incidences observed globally, including potential causes, and the impact of species mislabeling to human health, economics, and conservation.

Regulatory Frameworks for Seafood Authenticity and Traceability

Abstract The various national and regional regulatory requirements for seafood provide critical guidance for its harvest and sale. DNA analysis can often help industry to meet these requirements, both for local sale and for exporting products, and regulators to enforce them. When specific regulations are not in place, regulations from other regions may be helpful in developing guidelines. This chapter contrasts the more thorough regulations of the European Union with the frameworks in place in South Africa, a developing nation. It also discusses the changing state of seafood regulations in the United States, one of the worlds largest consumers of seafood, and how these regulations may impact global seafood sales. The integration, or potential integration, of DNA analysis is reviewed, including benefits and barriers from a regulatory perspective.

Species Identification Using Other Tools

Sequencing genomic samples utilizing conserved primers to the cytochrome oxidase subunit 1 (COI) gene is the most reliable and popular way to obtain information from PCR fragments for seafood identification. There are times when this procedure cannot be reliably implemented to identify a seafood sample; including when samples are mixed, two species within a genera are very closely related such as various tuna and snapper species, and when samples are highly processed resulting in the DNA being fairly degraded. This chapter discusses other molecular methods such as species-specific PCR primers, random-amplified polymorphic DNA fragments, and other approaches that can successfully be implemented to identify target species from more problematic samples when it is not conducive to sequence a sample using the conserved primers to COI.

Conclusion: DNA-Based Authentication of Shark Products and Implications for Conservation and Management

Given long generation times and relatively slow reproductive rates, elasmobranchs (sharks and rays) are particularly prone to overexploitation. The unrelenting demand for shark products is unsustainable and many shark fisheries are collapsing. Because of the urgency of addressing this situation, this book concludes with an overview of how DNA-based tools are being deployed for the identification of shark products in commercial trade and summarize the relevance of this information for conservation and management. Advances in reference sequence library construction, population-level identification methods, and instrumentation platforms, together with declining costs of conducting molecular diagnostic tests, will enhance the uptake of these tools for seafood authentication and traceability. However, as this text has demonstrated, they are already improving our ability to monitor patterns of exploitation and yield greater transparency in the industry. The results highlight the urgency of enforcing existing regulations and promoting additional measures to conserve the worlds shark fisheries.

An Introduction to DNA-Based Tools for Seafood Identification

DNA-based analysis for seafood authenticity and traceability allows for improved species- and population-level identification. This, in turn, allows the industry and regulators to better combat economic adulteration and the resulting health and conservation impacts. However, many different methods of DNA analysis exist for different applications. This chapter serves as an introduction to the basic molecular biology behind DNA analysis for those in the seafood industry with limited background in this area, including a review of DNA extraction, polymerase chain reaction (PCR) and gel electrophoresis, as well as a more basic description of specific analytical tools discussed in subsequent chapters. In addition, considerations for selecting an appropriate test and molecular marker are presented.