The Sonoyta pupfish gets its name from Mexico’s Rio Sonoyta, but the endangered species can no longer be found in that part of its historic range in northern Sonora.
According to University of Arizona freshwater biologist Michael Bogan, the feisty freshwater fish the length of a pinky finger went extinct in Mexico sometime last year.
That leaves Southern Arizona's Quitobaquito Springs in Organ Pipe Cactus National Monument as the only place on Earth where the species can still be found in the wild.
During the 20th century, the Rio Sonoyta south of the border had several perennial reaches where fish could be found year-round, but those gradually dried out amid unregulated groundwater pumping, warming and drought.
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Bogan said the species’ last refuge in Mexico was at a spot called Papalote, just across the border from Quitobaquito, where about a dozen shrinking pools still supported thousands of the fish.
Brett Montgomery, of Arizona Game and Fish, places some Sonoyta pupfish into an artificial stream inside the University of Arizona's Biosphere 2 in Oracle north of Tucson. The small endangered fish has disappeared from the wild in Mexico, an expert says.
“We weren't able to get in there as often because of narco activity, but we had reports and we knew that the pupfish were still in there,” he said. “Then the narco activity finally let up this past summer and some of my Mexican colleagues got in there in July, but they couldn't find any pupfish or water.”
Bogan confirmed the bad news himself when he visited the area in December. He found that some of the isolated pools had returned, but the fish had not.
“Sometime last summer, we lost the last wild population of the pupfish in Mexico,” he said. “Quitobaquito is the last natural place that it occurs,” but that spring system is now in jeopardy from more border wall construction in the area.
Luckily for the fish, there are a number of thriving refuge populations being kept in about a dozen artificial habitats throughout Arizona and Sonora, including one established last year inside Biosphere 2 north of Tucson.
Pupfish can also be found in Sonora at the zoo in Hermosillo and in a couple of manmade ponds in Rocky Point, Bogan said. There are even some being kept at the high school in the Mexican town of Sonoyta, just across the border from Lukeville.
“They have a little pond there, and the kids help take care of the pupfish,” Bogan said. “It's the mascot for the high school’s sports teams. It's awesome.”

