FRESNO, Calif.— The Center for Biological Diversity sued the U.S. Fish and Wildlife Service today for failing to finalize critical habitat protections for the Southern Sierra Nevada fisher.

“The Fish and Wildlife Service’s delay in protecting the forested lands that Southern Sierra Nevada fishers call home threatens the very survival of these adorable mammals,” said Andrea Zaccardi, carnivore conservation legal director at the Center. “By protecting the places where fishers live we can help them recover while also safeguarding California’s cherished wild landscapes.”

The fishers of the southern Sierra Nevada are medium-sized furry carnivores who are in the same family as weasels, mink, martens and otters. They depend on features found in old-growth forests such as tree cavities and downed wood.

Only found in North America, fishers were once well distributed throughout their historical range. But habitat destruction and climate change have contributed to their range-wide decline. Continued threats related to wildfires and wildfire suppression, increased temperatures resulting from climate change, disease and predation, exposure to rodenticides, collisions with vehicles and potential effects associated with small population size put the fishers at further risk of decline.

Following years of efforts by the Center and other conservation groups, the Service listed the southern Sierra Nevada population of the fisher as endangered in May 2020. The agency first proposed 554,454 acres of critical habitat in California’s Tulare, Kern, Fresno, Madera, Mariposa and Tuolumne counties in 2021, and added more than 40,000 acres in late 2022. Despite those proposals, the agency never finalized critical habitat designation and protections for the Southern Sierra Nevada fisher.

The designation of critical habitat is an important step in the fisher’s recovery. A Center study found that plants and animals with federally protected critical habitat are more than twice as likely to move toward recovery than species without it.

Last year the Service denied federal protections to a separate population of fishers found in northern California and southern Oregon, despite significant range loss due to logging, historic trapping, rodenticide poisoning and climate change.

Today’s lawsuit was filed in federal court in the District of Columbia.