The extent of population genetic subdivision differs among four co-distributed shark species in the Indo-Australian archipelago

Populations of four commercially harvested shark species (Carcharhinus obscurus, Carcharhinus sorrah, Prionace glauca, Sphyrna lewini) were sampled from northern Australia and central Indonesia. Neutral genetic markers (mitochondrial DNA control region sequence and allelic variation at co-dominant microsatellite loci) revealed genetic subdivision between Australian and Indonesian populations of C. sorrah. Further research is needed to address the possibility of genetic subdivision among C. obscurus populations. There was no evidence of genetic subdivision for P. glauca and S. lewini populations, but the sampling represented a relatively small part of their distributional range. For these species, more detailed analyses of population genetic structure is recommended in the future.Cooperative management between Australia and Indonesia is the best option at present for P. glauca and S. lewini, while C. sorrah and C. obscurus should be managed independently. On-going research on these and other exploited shark and ray species is strongly recommended. Biological and ecological similarity between species may not be a predictor of population genetic structure, so species-specific studies are recommended to provide new data to assist with sustainable fisheries management.The Indo-Australian archipelago is a biogeograhically complex region encompassing a series of continental shelves, volcanic mountainous islands and deep-sea trenches. The Indonesian section straddles the equator and extends about 5000 km from east to west. It has the world's highest marine endemism; including most the diverse sea-grass meadows, greatest expanses of mangroves and most extensive coral reef communities [1]. The Australian section is dominated by an extensive continental shelf extending offshore from three Australian state jurisdictions; Queensland, Northern Territory and Western Australia. As the world's fourth most populous nation, Indonesia has a high demand for food from the sea. The landed