Spatial habitat preference of smallmouth bass (Micropterus dolomieui), roundtail chub (Gila robusta), and razorback sucker (Xyaurchen texanus).

Abstract

Instream Flow Incremental Methodology (IFIM) and Habitat Evaluation Procedure (HEP), require the use of habitat preference curves to model the habitat requirements of fish. The accuracy of these curves has been questioned, particularly when they are applied outside the geographic area for which they were developed. Depth, velocity, substrate, and cover preference curves were developed for adult and juvenile smallmouth bass (Micropterus dolomieui) in Wet Beaver Creek, Arizona, and were compared to those from previous habitat preference studies in Virginia, Oklahoma, and Arizona. Curves for fishes in Wet Beaver Creek also were compared to curves developed using information from the scientific literature. Additionally, curves were developed for adult and subadult roundtail chub (Gila robusta) in Wet Beaver Creek, and adult roundtail chub and razorback sucker (Xyrauchen texanus) in Fossil Creek. The curves for adult roundtail chub were compared between these two locations. Velocity and depth preference curves, for both adult and juvenile smallmouth bass, appeared transferrable among locations. Minor differences between the depth curves were attributable to sampling techniques. Substrate preference curves were not transferrable; smallmouth bass seemed to use whatever substrates were locally available. No conclusion concerning the transferability of cover curves could be made because the definitions used for cover varied widely among investigators. Depth, velocity and substrate preferences of roundtail chub differed between the two streams studied, even though these streams were in the same drainage. The differences may have been related to the presence of smallmouth bass in Wet Beaver Creek; smallmouth bass were not present in Fossil Creek. Habitat preference curves based on depth, velocity, substrate, and cover parameters were developed for razorback suckers in Fossil Creek. No curves have been developed previously for razorback suckers in the lower Colorado River Basin; therefore, no comparisons were possible. This species was probably introduced into Fossil Creek and the habitat preference defined in this study may not represent razorback suckers throughout their range. Razorback suckers do not appear to have successfully spawned in Fossil Creek. This lack of success may reflect the absence of suitable habitat or simply indicate the fish have not reached sexual maturity.