Stocking of Gila topminnow, Poeciliopsis o. occidentalis, in Arizona’s Gila River Basin, an Arizona Game and Fish Department Central Arizona Fund Transfer Program update

Authors: Clayton D. Crowder, Ross J. Timmons

Year: 2009 (xli)

Abstract

Gila topminnow, Poeciliopsis o. occidentalis, a small, live bearing fish native to the Gila River basin in southwestern New Mexico and central Arizona, was federally listed as endangered within the United States in 1967. In Arizona, the topminnow is genetically represented by 8 meta-populations (lineages) at 14 historic localities. During the late 1970s through 1980s (a wet period), these lineages were stocked into as many suitable habitats as possible (a shotgun approach). As a result, the Gila topminnow has been stocked in more locations than any native fish in the southwest. However, due to impermanence of water, flooding, and invasion by nonnative fish, most of the reintroductions failed. In an effort to improve the success of topminnow reestablishments and recovery, emphasis moved to the protection of natural and reestablished populations in conjunction with a quality-driven approach of reintroduction to higher quality areas. In adoption of quality-driven reestablishment, the Arizona Game and Fish Department’s Central Arizona Project Fund Transfer Program (CAP Program) and its partners have successfully stocked and reestablished topminnow in 16 locations throughout the Gila River basin since May 2007. Partnering with county, state and federal landowners, the CAP Program stocked topminnow in locations that would enhance topminnow recovery by replicating the remaining natural populations in natural and human altered habitats. Each of these populations must persist for 10 years in order to contribute towards overall recovery. The successful establishment of these locations was largely due to initial site selection and evaluation.