"The Atlantic bluefin tuna Thunnus thynnus (Linnaeus 1758) is a highly migratory pelagic species found in the North Atlantic and Mediterranean Sea. The high market value of bluefin tuna has led to substantial overfishing, possibly lead to stock depletion unless sustainable catch quotas are enforced. Rational fish stock management requires knowledge of population structure; currently two separate Eastern and Western Atlantic stocks are recognized, spawning in the Mediterranean and the Gulf of Mexico respectively. Analysis of DNA markers such as microsatellite DNA and hypervariable mtDNA sequences mostly support the hypothesis of the Eastern and Western stocks, but suggest a more complex population structuring and the presence of other spawning sites in the Mediterranean. Single nucleotide polymorphisms (SNPs) are the most abundant polymorphisms in genomes; as sequencing is required for their characterisation, large numbers of SNPs were previously available only for model organisms. The advent of massively parallel sequencing platforms allows isolation of large numbers of SNPs in non-model species; current high-throughput genotyping platforms allow simultaneous analysis of SNPs of the same order of magnitude. Due to these technological advances, the use of SNPs in population studies is increasing and is anticipated to complement and eventually replace current DNA-based makers. The availability of a large number of SNP markers in the bluefin tuna would allow to analyse population structure in greater detail than with the currently used markers while facilitating data standardization across labs; addditionally, the genomic resources obtained from the project would significantly increase the level of genetic characterisation of ABFT and can provide the basis for future studies such as microarray development, marker validation and genetic linkage analysis."