Muddy River Blue Tilapia Oreochromis aureus Eradication Progress (A Cautiously Optimistic Tale of Successful Native Species Recovery in a Southwestern Stream)

Authors: Amos Rehm, Jake Mecham, Raymond Stevenson, Brandon Senger, Lee Simons

Year: 2016 (xlviii)

Abstract

The Muddy River originates as a series of thermal springs near Moapa, Nevada which support the endemic and endangered Moapa Dace Moapa coriacea as well as the Moapa variant of the White River Springfish Crenichthys baileyi moapae. These springs coalesce into the main stem, which supports a geographically distinct population of the endangered Virgin River Chub Gila seminuda and the Moapa Speckled Dace Rhinichthys osculus moapae. In the early 1990s Blue Tilapia Oreochromis aureus became established in the system, and precipitous declines in native fish populations were documented shortly thereafter. After considerable efforts were invested to successfully eradicate Blue Tilapia in the headwater springs, a Cooperative Recovery Initiative (CRI) grant was obtained to extend eradication efforts downstream into the main stem and encourage recovery of nat ive fish species in the Muddy River. This report summarizes the successes (and challenges) of the first year’s significant progress, including rotenone treatment of a 4 km segment of the river and attempts to re-establish the native fish assemblage of the Muddy River.