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  • Endangered Gila topminnow released at Agua Caliente Park

    May 13, 2020 | Read More News
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    Gila topminnow are swimming freely at Roy P. Drachman Agua Caliente Regional Park, thanks to the release of the endangered species May 13 into the park’s newly restored pond.

    Staff from the Pima County Natural Resources, Parks and Recreation Department, Office of Sustainability and Conservation, and the Arizona Game and Fish Department (AZGFD) topminnowreleased  500 topminnow into the newly restored main pond at the County-managed eastside park, 12325 E. Roger Road.

    Construction of the pond was completed in February 2020 after almost a year of work. The main spring, which historically fed the pond, began to experience significant decline in output beginning in approximately 2009 and by 2014 was completely dry. 

    To sustain this important historical feature, Pima County relied on well water, sometimes pumping as much as 1.8 million gallons a month to maintain the pond.  

    “This was not a sustainable model,” Karen Simms, Natural Resources division manager for NRPR, said.  Therefore, recent pond work included deepening the pond and mixing in a polymer that minimized seepage. While a few elements of the main pond remain to be complete, including a bridge to the island, the pond and park are now open for the public to enjoy.

    Pond conditions stabilized in the weeks following February’s completion, which allowed staff to add the native fish species. “This offers a way to educate the public about the breadth of native species that inhabit our unique Sonoran Desert environment and support of the goals of the Sonoran Desert Conservation Plan,” Simms said.
    Native longfin dace, one of the few native fish species that are not listed under the Endangered Species Act, were added to the pond in early May to see if they would survive this newly created environment. They, along with a single, large grass carp (put in the pond to control vegetation and algae) did well, Simms said, which allowed for the possibility of introducing the topminnow.   

    The Gila topminnow (Poeciliopsis occidentalis) is a small (1-2 inch) fish native to the greater Gila River watershed in Arizona, New Mexico, and northern Sonora, Mexico. Topminnow are in the same family as guppies, which bear live young, as opposed to laying eggs. Arizona Game and Fish and the U.S. Fish and Wildlife Service and their partners have worked to recover Gila topminnow by establishing new populations within its historical range ever since the species was listed as endangered in 1967. 

    Through conservation efforts, topminnow occur in several streams and numerous ponds in Pima County. In 2017, the fish returned naturally to the lower Santa Cruz, due to the upgrades to the two County wastewater treatment facilities that resulted in enhanced water quality in the river. In a recent partnership with Pima County, AZGFD biologists also released Gila topminnow into Edgar Canyon, on the east side of the Santa Catalina Mountains.

    The topminnow released May 13 will be periodically monitored by Pima County and the Game and Fish Department. Additional releases of native fishes, such as the endangered desert pupfish and Gila Chub (a threatened species), are planned in the future. 
    To maintain healthy conditions for these native fish, it is imperative that the public not release pets or plants of any kind into the pond. Doing so could threaten the success of the restoration effort. As a reminder, no fishing is allowed at the pond.