Potamodromous migrations, those that occur entirely in fresh waters, are made by a variety of minnows (Family Cyprinidae) in, and between, freshwater habitats around the world. These migrations most commonly are undertaken for purposes of breeding, feeding, or occupying specific habitats or refugia. There is a growing body of evidence that potamodromous migrations are undertaken by a number of cyprinids native to larger streams and rivers of the Great Plains region of central USA. Cross et al. (1985) observed that populations of Arkansas River shiner disappeared from large tributaries to the Arkansas River, in Kansas, as a result of dam construction and water withdrawal. They speculated that populations in these tributaries formerly were maintained by regular recolonization from downstream sites, which now was prevented by physical barriers and dewatered reaches of river. Similarly, Luttrell et al. (1999) documented the extirpation of peppered chub and shoal chub Macrhybopsis hyostoma from large portions of their ranges in the Arkansas River drainage. They attributed this to habitat fragmentation, especially as a result of reservoir construction, that prevented replenishment of populations in upstream sites by populations in downstream areas. Taylor et al. (1991) reported that plains minnow Hybognathus placitus and Red River shiner N. bairdi were most abundant in deeper, wider downstream areas of the Red River during fall, but that both species were more abundant in smaller, upstream sites during winter and spring, which they interpreted as evidence of migration in both species. More recently, Hoagstrom and Brooks (2005) suggested that Arkansas River shiner and Rio Grande shiner Notropis jemezanus made upstream migrations, based on systematic differences in length, abundance, and seasonal occurrence of both species in the Pecos River, New Mexico.
