MARE researchers publish pioneering study on the identification of tuna species in the Portuguese canning industry
MARE highlights the publication of the article ‘Identification of tuna species used by the Portuguese canning industry through a DNA-based approach’ in the journal Scientific Reports, part of the Nature group. The study, led by researcher Ana Rita Vieira, also involved the participation of MARE researchers Maria Inês Silva and Leonel S. Gordo. 
Although Portugal is one of the largest consumers of canned tuna per capita in Europe, little was known until now about the composition of the species used by the national canning industry. The team of researchers sought to fill this gap by using molecular sequencing methods capable of accurately identifying the species present in canned products.
According to Ana Rita Vieira, ‘This study represents the first comprehensive molecular portrait of the tuna canning industry in Portugal, revealing not only which species reach the consumer, but also the risks associated with inaccurate labelling.’
The study revealed that skipjack tuna (Katsuwonus pelamis) is the predominant species in all brands and types of canned tuna analysed. However, other species were also detected, namely Thunnus obesus, Thunnus albacares and Auxis spp., the latter of which is not considered a ‘true tuna’. Another relevant finding was the detection of multiple species within the same can in four different brands – a practice that violates current European legislation.
“By identifying tuna species with conservation status and species that are not true tuna, we demonstrate the importance of strengthening control mechanisms for accurate labelling, in order to ensure that consumers know exactly what they are buying and consuming,” Ana Rita Vieira begins by explaining. “The identification of mixed species in the same can highlights non-compliance with current European legislation and reinforces the urgency of more robust traceability mechanisms.”
This inconsistency may be due to supply strategies, market preferences or seasonal variability in the availability of species. In fact, the presence of alternative species was only observed in canned products produced in the second quarter of the year.
The work now published is the first comprehensive assessment of the species used by the tuna canning industry in Portugal. For Ana Rita Vieira, ‘Accurate identification of species is an essential step in protecting vulnerable stocks and ensuring the sustainability of tuna fishing.’
The Portuguese canning industry is a historical and economic benchmark. ‘This study does not aim to point out flaws, but rather to provide solid scientific information on the specific composition of products available on the national market, contributing to a more informed debate on the use of resources and labelling practices,’ she concludes.
Written by Patrícia Carvalho
Photographs from the research project