Assessing the elemental fingerprints of cockle shells (Cerastoderma edule) to confirm their geographic origin from regional to international spatial scales

Geographic origin is directly linked to the quality and commercial value of bivalves. The globalization of the seafood trade and the increasing number of fraudulent practices in the bivalves industry has prompted consumers to become increasingly aware on the geographic origin of the seafood they consume. To enhance consumers' confidence and allow authorities to effectively enforce regulations and contain risks that threaten public health, fast and accurate tools must be made available to confirm claims along the trade chain on the geographic origin of bivalves. In the present study the efficiency of using the elemental fingerprints of a small-homogenized subsample of the shell of common cockles (Cerastoderma edule) to confirm their harvesting location is evaluated at different spatial scales: i) regional (along the Galician coast (Spain) - Espasante, Barallobre, Rio Anllons, Camarinas, Muros, Noia, Carril, Grove, Combarro, Placeres, Moana, and Baiona), ii) national (along the Portuguese coast - Ria de Aveiro, Obidos lagoon, Tagus estuary, Sado estuary and Ria Formosa), and iii) international (along the Northeast Atlantic coast - Hejeltefjorden (Norway), Nykobing Mors (Denmark), Sylt (Germany), Slikken van Viane (Netherlands), Roscoff (France), Plymouth (England), Swansea (Wales), Ria de Aveiro (Portugal) and Oualidia (Morocco). Results confirm that elemental fingerprints of bivalve shells arc significantly different among locations and that they can be successfully used with high accuracy to discriminate the geographic origin of cockles at all spatial scales surveyed (97.2% at regional scale, 99.3% at national scale and 100% at international scale). Overall, elemental fingerprints of a small-homogenized subsample of the shell showed to be a replicable, low cost and fast tool to reliably trace the place of origin of cockles sampled at different spatial scales, with success rate of discrimination directly increasing with distance between collection sites.

Automated summary

The geographic origin of bivalves is closely linked to their quality and commercial value. A study has shown that analyzing the elemental fingerprints of bivalve shells can accurately determine their harvesting location at different spatial scales, providing a fast and low-cost tool for tracing the origin of bivalves.