Stream-Specific and Generalized Habitat Suitability Criteria for Four Native Desert Fishes

Authors: Zach Nemec, Scott Bonar

Year: 2018

Abstract

Endemic fishes of the arid southwestern United States have rapidly declined due to anthropogenic stressors. Identifying the habitat conditions needed by these species is critical for their successful management. Habitat suitability criteria are commonly used to conserve species of interest. Therefore, developing habitat suitability criteria for native fish species across multiple rivers permits better understanding of how different environments are occupied under various circumstances. We developed stream-specific and generalized criteria for Longfin Dace, Agosia chrysogaster, Speckled Dace, Rhinichthys osculus, Desert Sucker, Catostomus clarkii, and Sonora Sucker, Catostomus insignis across four central Arizona streams. Over 1,200 sites were sampled using pre-positioned electrofishing devices during the 2017 summer low-flow period to identify relationships among fish presence and habitat variables (depth, velocity, substrate class, capture temperature, and canopy cover). Optimal (central 50% of range used) and suitable (central 95% of range used) ranges within each habitat variable were calculated for each stream, based on the occurrence of each species. In general, Longfin Dace occupied depths of 9.00 – 54.75 cm (14.25 – 27.25 cm) velocities of 0.00 – 0.63 m/sec (0.11 – 0.31 m/sec), and substrate (modified Wentworth scale) of 0.5 – 4.3 (2.1 – 3.3). Speckled Dace occupied depths of 8.25 – 74.00 cm (17.00 – 34.25 cm) velocities of 0.00 – 0.74 m/sec (0.16 – 0.43 m/sec), and substrate of 0.0 – 4.5 (2.2 – 3.6). Desert Sucker occupied depths of 9.00 – 45.00 cm (15.25 – 25.00 cm) velocities of 0.09 – 0.72 m/sec (0.21 – 0.44 m/sec), and substrate of 1.0 – 4.6 (2.5 – 3.7). Sonora Sucker occupied depths of 9.20 – 61.40 cm (17.80 – 37.70 cm) velocities of 0.06 – 0.68 m/sec (0.15 – 0.28 m/sec), and substrate of 0.5 – 5.0 (2.4 – 3.2). Most of the generalized habitat suitability criteria for all four species did not transfer into study streams. Agencies should develop stream-specific habitat suitability criteria when managing species of interest for a certain stream.