Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

Abstract

ABSTRACT Little is known about the distribution and status of native fishes in the Green River drainage of southwestern Wyoming, particularly bluehead sucker <em>Catostomus discobolus</em>, flannelmouth <em>sucker C. latipinnis</em>, and roundtail chub <em>Gila robusta</em>. These species face a number of threats to their continued survival in Wyoming, including predation by nonnative fishes and competition and hybridization with nonnative fishes, habitat fragmentation (caused by water development and stream dewatering), and habitat destruction (caused by livestock grazing and road construction). Due to these threats, this project was undertaken to gather information to guide future management of these species. Objectives included determining current distribution and abundance of the three species, determining the extent of hybridization with nonnative species, and documenting overall species composition throughout the study area. Sampling began in 2003, and efforts were focused on the eastern portion of the Green River watershed between Fontenelle and Flaming Gorge reservoirs. Twenty-three fish species were identified in 60 sites; only seven were native. Flannelmouth sucker were widely distributed throughout the study area. Bluehead sucker were less abundant and were limited to the main-stem Green River and the upper Big Sandy River and upper Little Sandy Creek. Perhaps the biggest threat to these native suckers is hybridization with widely distributed introduced white sucker <em>Catostomus commersonii</em>. Roundtail chub were not collected during 2003 surveys, but still exist in other portions of the drainage in Wyoming. This is an ongoing project, and sampling will continue in remaining portions of the drainage in subsequent years.