Prionace glaucais thought to be one of the most common and studied pelagic sharks, and yet few is known about its population structure. Blue sharks are fished, mainly as bycatch, across their nearly worldwide (except at polar latitudes), distribution area. The estimated removal of 20 million individuals per year by fisheries classifies blue sharks as near threatened (IUCN, 2009). However, the lack of knowledge of population size and structure, the high fecundity and early maturation of P. glaucaas well as its apparent stable catch rate make it difficult to forecast the long term consequences of such a huge removal on this top-down predator itself, and on its trophic network. Tags studies identified stocks in North Atlantic and in Pacific Ocean with few migrants capable of ten thousand kilometers travels and previous genetic studies concluded to panmixia at the scale of the Pacific Ocean. Here we will present worldwide genetic results on mitochondrial and nuclear DNA with 258 blue shark samples from eight regions.