In 1979, nonnative trout pushed Arizona’s Apache trout into 30 stream miles; today, 30 populations occupy 175 miles, and it’s off the endangered list
Arizona’s state fish grew from 14 known populations to 30. Here is how barriers and careful removal of nonnative trout brought it back.
In 1979, the Apache trout population in Arizona had dwindled to 14 populations occupying only 30 miles of river habitat. This decline was largely due to the presence of nonnative trout species, such as rainbow, brook, and brown trout, which interbred with the Apache trout, diluting their genetic identity and competing for resources. In response, conservation efforts were initiated to protect the remaining populations and control the spread of nonnative fish.
By 2024, the recovery of the Apache trout had been successful enough to warrant its removal from the endangered species list. The U.S. Fish and Wildlife Service cited habitat protection and control of nonnative fish as the key factors in this achievement. The 2022 species status assessment highlighted that 30 populations now occupy 175 miles of stream habitat, meeting the recovery goals that had long required at least 30 genetically pure populations with suitable habitat conditions.
The recovery process involved several strategies, including installing physical barriers to prevent nonnative trout from moving upstream and removing established nonnative populations through chemical treatments and electrofishing. Since 2011, when wildfires caused significant damage to the existing protections, managers have been continuously maintaining and upgrading these barriers, with the most recent example being the replacement of the Big Bonito Creek barrier in 2025, which added protection for 22 miles of stream habitat.
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