The U.S. Fish and Wildlife Service is proposing new federal protections for two rare species of river mussels found only in the Rio Grande in parts of West and South Texas.
The agency on Monday released a proposal to place the Salina mucket and Mexican fawnsfoot mussels on the endangered species list. The move would also designate more than 385 miles of the Rio Grande in Texas as critical habitat for the freshwater animals.
“Because the single existing populations of both species have low abundance, limited recruitment, and no ability to disperse into new areas, they are extremely vulnerable to extinction,” Amy Lueders, regional director of the agency’s southwest office, said in a statement.
Both species of mussels were once found across a larger swath of the Rio Grande watershed but now only live in two stretches of the river, one downstream from Big Bend National Park and the other between Eagle Pass and San Ygnacio, Texas.
The proposal is the latest in a series of federal efforts to protect dwindling mussel populations in the U.S. that experts say are crucial for the health of rivers and streams. According to the Fish and Wildlife Service, more than 70% of the 300 freshwater mussel species in the U.S. are currently considered endangered, threatened, or “of special concern” due to their habitats being lost, fragmented or degraded.
Unlike invasive Zebra mussels that continue to plague Central Texas lakes, native mussels are vital to the health of river ecosystems and aquatic life.
“They filter liters and liters of water, helping improve water quality, they help stabilize streambeds, they serve as a food resource for a number of animals,” Matthew Johnson, a Texas-based biologist with the Fish and Wildlife Service, said in an interview.
The agency is taking public comments on the proposal through Sept. 25 and could make a final decision on the endangered species listing within a year.
The portions of the Rio Grande that would be designated critical habitat under the proposal include parts of the river corridor in Big Bend National Park and multiple state-owned conservation areas, including the Black Gap Wildlife Management Area.
Rick Gupman, the national park’s acting superintendent, said the National Park Service “fully supports the move.” A spokesperson for the Texas Parks and Wildlife Department said it is currently reviewing the federal proposal and plans to file formal comments on the matter.
According to the Fish and Wildlife Service, the critical habitat designations for the stretches of river in West and South Texas would not lead to new restrictions for landowners or state agencies and would impose “no requirements on state or private actions on state or private lands where no federal funding, permits, or approvals are required.”
Still, the agency’s placement of another Texas mussel on the endangered species list in 2018 prompted some pushback in neighboring New Mexico and concerns about the listing’s potential impact on property rights. It’s unclear if the new proposal will lead to similar concerns in Texas.
Environmental groups applauded Monday’s announcement but criticized the Fish and Wildlife Service for not acting sooner on the matter.
The Center for Biological Diversity, which sued to force the mussels protections in 2020, noted in a statement that the Salina mucket and Mexican fawnsfoot had been under consideration for an endangered species listing for more than a decade. As part of a recent settlement deal, the group dropped its legal claims related to the mussels after the Fish and Wildlife Service announced it was voluntarily pursuing the listing.
“It shouldn’t take the U.S. Fish and Wildlife Service this long to protect such clearly imperiled species,” Michael Robinson, an advocate with the group, said in a statement. “This agency is badly in need of new leadership and reform, and it’s past time for the Biden administration to make that happen.”
Both mussels species are already listed as threatened under Texas law. A spokesperson for the Texas Parks and Wildlife Department said the mussels are currently the subjects of various conservation efforts coordinated by the state and private landowners along the Rio Grande.
The environmental group WildEarth Guardians has also been involved in the push for mussels protections in Texas, stemming back to petitions the group filed on the matter about 15 years ago.
Joanna Zhang, a rivers advocate with the group, described the mussels’ fate as intertwined with that of the river they call home.
“More of the Rio Grande is disconnected and drying up every year,” she said. “The way we’ve been managing the Rio Grande has drained the river of its vitality, and it’s encouraging to see the Service proposing protections that would help safeguard a healthy and flowing river for these mussels and other species.”
Johnson, the Fish and Wildlife Service biologist, said the Rio Grande mussels are worth protecting, small and relatively unknown to the broader public as they may be.
“The nature around us, the trees, the flora, the fauna, they help make a place what it is,” he said. “So I think it’s in our best interest to try to preserve everything that’s out there that makes the place that we call home unique.”
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