TUCSON, Ariz.— Responding to a formal notice of intent to sue from the Center for Biological Diversity, the U.S. Fish and Wildlife Service today announced that it will grant expanded critical habitat designations for the Sonora chub, a small desert fish facing multiple major threats — but the agency will delay that action until at least 2027.

“The Sonoran chub needs these protections immediately, so waiting another three years will be a death sentence for this rare desert fish,” said Taylor McKinnon, Southwest director at the Center for Biological Diversity. “There are only two remaining populations of Sonora chub in the United States and one is being left to fend for itself. If the Fish and Wildlife Service is serious about saving this species from extinction it needs to act now.”

Critical habitat was designated for the Sonora chub in 1986 to include the entire U.S. range of the species known at the time. But a second population was later discovered nearby, in southeast Arizona’s California Gulch.

In 2023 the Center filed a formal petition to designate approximately 4 miles of California Gulch as critical habitat, starting at the international border. That was followed in March 2024 by a notice of intent to sue.

California Gulch has habitat features such as perennial pools that are essential to the conservation of the Sonora chub. The gulch also acts a migration corridor between Mexico and the United States.

One major threat to the Sonora chub in California Gulch is grazing by livestock, which can trample the fish and pollute and degrade their habitat. Damage from livestock grazing has already been documented in the chub’s habitat.

Another threat is border infrastructure development: The government plans to close numerous small gaps in the border wall such as the one that California Gulch flows through.

Mining, climate change, water development and non-native species also threaten Sonora chub and their habitat.