Are Gila Topminnow Still In Danger of Extinction?

Authors: Anthony T. Robinson

Year: 2016 (xlviii)

Abstract

Gila topminnow, Poeciliopsis occidentalis, status has improved since the recovery plan was finalized in 1984. At that time, Gila topminnow was present in 15 localities: 9 natural and 6 repatriated populations. Gila topminnow were stocked into over a hund red sites in the 1980s, and by 1989, it was thought the species could be reclassified as threatened. However, drought and nonnative species caused most of the populations established in the 1980’s to disappear. By 1998, when a draft revised recovery plan wa s completed, there were 44 populations: 14 natural; 18 repatriated into wild locations, and 12 captive. Repatriations have continued, and there are now 88 locations with Gila topminnow; but 16 of those were stocked in the last three years. Therefore, 72 popul ations have persisted for more than three years: 11 natural; 31 wild repatriations, 30 captive. Each of the five recognized genetic management has multiple replicates: 21 Monkey/Cottonwood Springs, 18 Bylas Springs, 13 Cienega Creek, 11 Lower Santa Cruz, and 9 Sharp Spring. Further, the 72 populations are widely spread across the Gila River basin: 9 in the Gila River Basin above Coolidge Dam, 19 in the Salt River Drainage, 6 in the Agua Fria drainage, 8 in the San Pedro River drainage, 23 in the Santa Cruz River drainage, and 7 at conservation facilities. Therefore, because each genetic management unit has multiple replicates, and the 72-88 populations are widely distributed across the Gila River Basin, the risk of extinction is extremely low. Reclassifying the species as threatened is warranted.