Global Population Genomic Structure of Yellowfin Tuna (Thunnus albacares)

Despite the relevance in resolving the population dynamics and structure of tuna and tuna-like species, their genetic population structure is not well resolved yet, with several studies leading to discordant lines of evidence, as in yellowfin tuna, Thunnus albacares (YFT), whose population structure is still surrounded by uncertainties both at the global and local scale. These uncertainties might be a direct consequence of the limited genetic resolution of classical molecular markers in detecting the population structure of highly-migratory fish species.

In such a context, for the first time, here we applied the 2b-RAD genotyping technique for investigating YFT population genetic structure across the Atlantic, Indian and Pacific oceans. Based on the SNP markers discovered, the global YFT population structure was revealed at a level unattainable through classical molecular approaches, with significant implication for its stock assessment and management.

In fact, our results showed a higher level of structuring in the Atlantic than generally assumed by the International Commission for the Conservation of Atlantic Tuna, which should be assessed and, potentially, managed independently. All this underlines the evident need to re-examine previous biological assumptions about YFT stocks’ productivity and resilience to the fishing pressures in the Atlantic Ocean.