The goal of this study will be to define the genetic relatedness within and among Rio Grande chub populations throughout New Mexico, Southern Colorado, and Texas. We hypothesize a small effective population size (Ne) and fragmentation of populations of Rio Grande chub have resulted in reduced genetic diversity; and, the relatedness of populations will be directly related to connectivity among populations. From extant populations of Rio Grande chub among three drainage basins, we will use microsatellite markers to determine how gene flow is affected by distance among basins and degree of connectivity among populations within basins. The results of this research can be used to guide decisions in supplementing or establishing new Rio Grande chub populations and identify which populations serve as a source for genetic material for future translocations. I anticipate this work will provide information that can be used by fisheries managers on federal and state lands in the development of a conservation plan for the species. Historical surveys of the species distribution began during the reporting period.