Distribution, abundance, and habitat use of Rio Grande sucker (Catostomus plebeius) in Hot Creek, Colorado

Rio Grande sucker, Catostomus plebeius, has declined in the Rio Grande Basi n in Colorado, and was listed as a Colorado state endangered species in 199 3. The fish is now known to occur in only one location, Hot Creek. We docum ented distribution and abundance of Rio Grande sucker in Hot Creek in 1994 and described aspects of its biology, habitat use, and fish assemblage. Rio Grande sucker occurred in about 8 km of Hot Creek, with a stream wide popu lation size of 1,426 fish (95% confidence interval = 651-2,201). The only m icro- or meso-scale habitat characteristic that was related to Rio Grande s ucker abundance was amount of fine sediment. Hybridization with the nonnati ve white sucker does not appear to be a major factor in decline of Rio Gran de sucker in Colorado but other biotic interactions with that species may b e important.