Traceability of mussel (Mytilus chilensis) in southern Chile using microsatellite molecular markers and assignment algorithms. Exploratory survey

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The international seafood trade has adopted the food chain or “from farm to fork” concept in terms of standards and regulations regarding food quality, safety and authenticity, from primary production to the consumer. This has led to an increasing need for traceability, but administrative traceability systems (physical labeling, information recording and automatic data treatment) are not flawless and require validation through analytical procedures. Currently, DNA-based methods used for species identification and population genetics, coupled with allocation algorithms can be used to verify administrative traceability systems. We evaluated the potential of a panel of nine microsatellite markers combined with allocation algorithms for their ability to assign Mytilus individuals from southern Chile to their geographical origin, evaluating the performance of four assignment methods: genetic distance and frequency-based criteria and a Bayesian based method using prior information or not. The reallocation test showed that the Bayesian method with prior information performed best. When tested with a real traceability verification case, the frequency-based algorithm showed the best results, re-allocating individuals to their original population at least 6 times more often than individuals from other locations in a challenging scenario with low genetic differentiation among locations. In order to apply this allocation method for traceability purposes, it would be necessary to strengthen this SSR panel with more informative loci and complement it with SNP markers.