Forensic assignment to geographic origin, a useful tool in seafood fraud control

•Only one Atlantic salmon catch of the angling season can be sold in Northern Spain.•The first salmon catch of the year 2011 was denounced on regional Court for fraud.•Fisherman declaration did not match with genetic assignments to a rivers baseline.•This methodology was useful as a reinforcement of other evidences in Court.•This is the first judicial case employing these genetic evidences in a fish species in Spain.

Seafood fraud is an economically motivated and widely spread problem encompassing drastic consequences in both public health and species conservation. In Northern Spain, only the first Atlantic salmon (Salmo salar) catch of the angling season (named Campanu) can be sold. In the year 2011, an angler denounced it on regional Court claiming that the Campanu (which was sold in 6000€) was fraudulent because it had been caught from another river than the fisherman (“the seller”) stated. Here, we report the first judicial case of application of geographical genetic assignment in a fish species in Spain. In order to accomplish this, genetic assignments to their rivers of origin of the Campanu and another three following salmon catches of the angling season of the year 2011 were performed. A panel of eight microsatellite loci together with a comprehensive genetic baseline of the rivers of the region were employed. Results showed that the Campanu was the only case in which genetic assignment and fisherman declaration of the river of origin did not match. The methodology here employed showed to be very useful as a reinforcement of other evidences contributing to fight against seafood fraud in Courts.