Use of hydrographic data and historic species locations to select potential streams for repatriation of spikedace (Meda fulgida) and loach minnow (Tiaroga cobitis)

Authors: Anthony T. Robinson, Nicole L. Eiden

Year: 2013 (xlv)

Abstract

We used the Lower Colorado River Basin Aquatic Gap Analysis Dataset and the Environmental Protection Agency’s National Hydrography Dataset Plus (NHDPlus) to determine ranges in several large-scale geographic features for stream reaches with historic locations of spikedace (Meda fulgida) and loach minnow (Tiaroga cobitis), and then used that information to predict potential stream reaches to repatriate the species within the Gila River Basin. All stream reaches less than 1 km long were merged with the reach above or below so that the data for analysis would be within a 1 to 15 km scale. Selected geographic features were gradient (m/100m = %), elevation (m) at the upstream end of each reach, and Shreve stream order. Shreve stream order was used as a proxy for discharge, for which information was lacking on the vast majority of streams. For spikedace, ranges were 0.083 to 4.38% gradient, 354 to 2,107 m elevation, and 28 to 7135 Shreve stream order. For loach minnow, ranges were 0.086 to 5.59% gradient, 699 to 2,577 m elevation, and 3 to 1224 Shreve stream order. We used these ranges as criteria to select stream reaches within the Gila River basin upstream of the confluence of the Gila and Agua Fria rivers for spikedace and upstream of the confluence of the Salt and Gila rivers for loach minnow; the Santa Cruz River and Wilcox Playa drainages were excluded for both species because there weren’t any historical records for either species in those drainages. The result for spikedace was 2,507 reaches that included 108 named streams and numerous segments missing stream names in the data. For loach minnow there were 7,167 reaches that included 450 named streams and numerous unnamed segments. However, only about 51 of these potential spikedace streams and 150 of the potential loach minnow streams in Arizona are known to be perennial. These perennial streams should be further evaluated, and those with suitable habitat, sufficient length of perennial water, and absence of nonnative fishes or the potential to remove them should be targeted for repatriation of the species.