Effective conservation and management strategies of marine species require a fundamental understanding of their population structure. Molecular genetic data can be used to discern this information by quantifying the degree of relatedness between specimens from different locations. The PSRC has initiated genetic research into the population structure of the common thresher shark (Alopias vulpinus). These sharks are found throughout the world’s warm and temperate oceans and are often targeted by commercial fisheries. Specimens and tissue will be collected throughout the Pacific Ocean, and perhaps other areas of the world. Through analysis of DNA sequences from microsatellites and the mitochondrial control region, we will assess the levels of genetic diversity among global populations of thresher sharks to determine if the species’ potential for large-scale dispersal is translated into broad gene flow throughout its range. Successful completion of this research will clarify the extent of common thresher shark movements and may reveal population subdivisions that require special attention for sustainable fisheries management.