The status and conservation of the Gila Topminnow

Authors: Douglas K. Duncan, Ross J. Timmons

Year: 2014 (xlvi)

Abstract

The Gila topminnow, Poeciliopsis occidentalis, was once considered the commonest fish in the Gila River basin. Due to the well-known and extensively documented threats of habitat desiccation and the release of exotic and nonnative fishes, this once common live-bearer was reduced to a few isolated populations, and listed as an endangered species in 1967. Gila topminnow have been released over 200 times into mostly wild habitats (streams, springs, stock tanks, ponds), and more than 100 times into captive sites. These numbers include the initial and augmentation releases, and have been largely over the last 35 years. The releases have been facilitated by MOUs, Endangered Species Act Section 6 funding, Arizona Heritage Funds, the topminnow pupfish Safe Harbor Agreement, and the Gila River Basin Native Fish Conservation Program. Most releases were done by the Arizona Game and Fish Department, but have included numerous partners. The topminnow pupfish Safe Harbor Agreement has allowed the release of topminnow into lands that would normally not be available for native fish conservation. Work on the revision to the 1983 recovery plan revision continues, with a public draft expected in 2015. We also plan on completing the five-year review for the Gila topminnow concurrently with the public draft of the recovery plan. The current conservation program is guided by the current draft revised recovery plan, which is the best-available information on the subject. We hope that the current robust conservation actions for the Gila topminnow could lead to down-listing in the foreseeable future. One strategy we have contemplated with a down-listing to threatened status is an Endangered Species Act 4d rule that would allow the use of Gila topminnow for vector control, instead of western mosquitofish, Gambusia affinis. Status of the species has improved with the recovery actions, but the threats that lead to the endangered status of the Gila topminnow continue. Drought, climate change, and increasing human populations still threaten streams and springs and nonnative and exotic species are still introduced and distributed across the landscape. An open-pit copper mine proposed near Tucson will impact Cienega Creek, home of the largest and most robust natural Gila topminnow population in the U.S. In addition, and another open-pit mine is proposed in Mexico near the Santa Cruz River. The spill from the mine near Cananea most certainly impacted topminnow in the Rio Sonora in Mexico.

Resumen

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