Spatio-temporal microsatellite data suggest a multidirectional connectivity pattern in the Trachurus picturatus metapopulation from the Northeast Atlantic

Abstract The sustainable management of fisheries requires knowledge on their spatio-temporal delineation as well as on the connectivity pattern within metapopulations. The blue jack mackerel Trachurus picturatus is an important fishery in South Western Europe but its population structure and connectivity patterns remain controversial. This study is the first one employing microsatellite markers on T. picturatus to unravel the population structure and migration dynamics among fishing grounds sampled in 2013 and 2016 in the Northeast Atlantic and the Mediterranean Sea. Microsatellites show high spatio-temporal conservation of gene diversity (HE = 0.851 ± 0.011) and the absence of genetic differentiation among samples (FST = 0.0013 ± 0.0020) in the whole range. Current genetic data suggest that T. picturatus fishery consists of a metapopulation exhibiting high gene flow among the fishing grounds tested so far. These results are consistent with the scenario recently reported with mtDNA genes. Moreover, the Bayesian-computed migration rates and common ancestry suggest a large multidirectional migration (m ≥ 0.30) across a Northeast Atlantic longitudinal corridor. A directional property of the connectivity pattern is that migration proceeds from Macaronesia to Portugal mainland in autumn-winter while the way back seems to occur in spring-summer. The information retrieved from life-cycle markers (otoliths, morphometrics, etc.) is also discussed in the light of the new molecular data. Upcoming scientific challenges for the sustainability of this fishery should focus on the full characterization of the remaining properties of its connectivity patterns and on the contribution of each local recruitment area to the adult fishing grounds.