Genetic Variation and Stock Structure of Blackfin Tuna Inferred from Microsatellite Loci

The blackfin tuna (Thunnus atlanticus) is a small tuna found in tropical and subtropical waters of the Western Atlantic Ocean. Over the last decade, the species has been increasingly exploited by fisheries in several parts of its range. Despite of this rising interest, management of the stock is still non-existent. In this context, knowledge of stock structure is required in order to develop coordinated management of this resource accounting for sub-units of the stock if they exist. In this work, 20 new homologous microsatellite markers were developed for blackfin tuna and tested on a sample of 35 specimens collected offshore La Martinique in order to identify a panel of 15 loci suitable for population genetics studies. The selected markers are being used in a survey of genetic variation among 7 localities encompassing most of the species range. Reproductively active fish were targeted in priority during sampling in order to facilitate interpretations towards understanding the breeding structure of the species. This study will provide essential data on stock structure and on the connectivity among geographic populations which will enable the development of sustainable conservation and management plans for this resource.