The Peppered Chub Macrhybopsis tetranema was once found throughout the Arkansas River basin in portions of Texas, New Mexico, Oklahoma, Kansas, and Colorado. Range-wide declines in both abundance and distribution have occurred over the past three decades coinciding with habitat loss and fragmentation. Over the last decade or more, only two geographically isolated Peppered Chub populations persisted in the Arkansas and Ninnescah rivers in Kansas and a portion of the Canadian River in New Mexico and Texas.
Intensive sampling between 2011 and 2013 documented the decline of this species from Kansas during consecutive years of region-wide drought in 2011 and 2012. Equally intensive sampling in 2015 in reaches of the Ninnescah and Arkansas rivers yielded no individuals, suggesting the potential extirpation of this population. Conversely, Peppered Chub were consistently collected in the Canadian River in New Mexico from 2012 to 2015, with increasing numbers in recent years with higher flows. Therefore, Peppered Chub is either extirpated or has declined below detection in Kansas and a stable population only remains in a 220 km reach of the Canadian River.
A recovery plan for the Peppered Chub might consider restoration and maintenance of adequate seasonal fluctuating river flows, removal of barriers, and repatriation to river reaches that have experienced extirpation.