Assessing the elemental fingerprints of cockle shells (Cerastoderma edule) to confirm their geographic origin from regional to international spatial scales
Abstract
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 pres-
ent 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 Anllóns, Camariñas, Muros, Noia, Carril, Grove,
Combarro, Placeres, Moaña, and Baiona), ii) national (along the Portuguese coast - Ria de Aveiro, Óbidos 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 are significantly different among locations and that they can be success-
fully 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 dis-
tance between collection sites.