Still time for action: genetic conservation of imperiled South Canadian River fishes, Arkansas River Shiner (Notropis girardi), Peppered Chub (Macrhybopsis tetranema) and Plains Minnow (Hybognathus placitus)

Pelagic broadcast spawning cyprinids have declined throughout the North American Great Plains because of adverse habitat changes caused by river fragmentation and altered flow regimes. Despite losses elsewhere, a 218-river kilometer section of the South Canadian River maintains three of these imperiled species: Arkansas River Shiner, Peppered Chub and Plains Minnow. The objective of this study was to determine if species occupying the same river stretch and hence a shared environment, exhibit the same trajectory of genetic change and relative abundance over contemporary timescales. Genetic evaluation of these species is an essential precursor to conservation efforts that may include translocations and establishment of captive populations. Across the time series, each species experienced substantial changes in abundance with Arkansas River Shiner consistently having the highest overall abundance. The abundance of Peppered Chub was uniformly lower but increased between 2012 and 2019, while Plains Minnow abundance declined from 2012 to 2019. Despite dramatic fluctuations in population size over the time series, data from microsatellites and mitochondrial DNA demonstrated that the South Canadian River harbors genetically diverse populations of each of these species. With the Southwestern United States entering another period of exceptional drought, immediate intervention is necessary to ensure persistence of range-restricted Arkansas River Shiner and Peppered Chub. Results of this study show that remnant populations provide a crucial resource for recovery efforts for these species.