Stream monitoring in the Gila River Drainage, Fall 2012

Authors: Lara Upton

Year: 2013 (xlv)

Abstract

From September to November, 2012, native fish biologists from the Arizona Game and Fish Department Non-game Branch surveyed twelve streams in the Gila River Basin as part of an ongoing effort to monitor native species and detect invasive species in the Gila River drainage. For each stream, one or two of the following threatened or endangered native fishes, known to historically occupy these systems, were targeted: Gila chub, Gila intermedia, headwater chub, Gila nigra, roundtail chub, Gila robusta, Gila topminnow, Poeciliopsis o. occidentalis, spikedace, Meda fulgida and loach minnow, Tiaroga cobitis. Sampling methods used to conduct the monitoring were back-pack electroshocker, hoop nets, minnow traps and seines. Initial qualitative sampling at a site required surveying a 500m reach to detect the target species. When the target species was detected, a 100m quantitative reach was established by delineating habitat into run, riffle and pool sections and surveying each individually. Thirteen species were detected across twelve streams, including six native species. Target species and other natives were encountered at ten of the twelve streams, and eight streams were free of non-native species at the sites surveyed.