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Expert contacts

Sarina Jepsen, Endangered Species Program Director, Xerces Society for Invertebrate Conservation
(971) 244-3727   |   [email protected]
(Available 7/26/21 until 2:00 p.m. Pacific and 7/27/21.)

Candace Fallon, Senior Conservation Biologist, Xerces Society for Invertebrate Conservation
(503) 232-6639 x118   |   [email protected]

Scott Black, Executive Director, Xerces Society for Invertebrate Conservation
(503) 449-3792   |   [email protected]


PORTLAND, Ore.; Monday, July 26, 2021---Responding to a petition from the Xerces Society for Invertebrate Conservation, the U.S. Fish and Wildlife Service today announced that protection may be warranted for the western ridged mussel (Gonidea angulata), and that it is initiating a status review of the species.

The western ridged mussel has been lost from more than 40% of its range, including an approximate 475-mile range contraction northward in California. It has been subject to recent, unexplained mass die-offs in multiple rivers across its range, including the Chehalis River in Washington and both the Middle Fork John Day and Crooked Rivers in Oregon. At sites where die-offs have occurred, biologists have observed thousands of dead and dying mussels spanning tens of river miles.

The western ridged mussel faces multiple threats, including direct habitat destruction and modification; impacts to water, including water management, water quality, and climate change; and the potential for introduction of invasive species such as zebra mussels. The recent mass die-offs mentioned above and dwindling populations emphasize the need for swift action.

“We are so pleased that the U.S. Fish and Wildlife Service has taken this important first step toward protection of the western ridged mussel,” said Emilie Blevins, lead author of the petition and senior conservation biologist at the Xerces Society. “Given the imminent threat of these unexplained die-offs, we hope the Service will swiftly take the necessary steps to ensure protection of the species.”

This is the first species of freshwater mussel in western North America to be considered for Endangered Species Act protection by the U.S. Fish and Wildlife Service, although more than 90 species of freshwater mussels are listed in the United States as Endangered, Threatened or have already gone extinct. Indeed, freshwater mollusks (including mussels and snails), are the most imperiled group of animals in the United States.

The western ridged mussel inhabits rivers and streams in Oregon, Washington, Idaho, Nevada, California and British Columbia and improves water quality for salmon and other wildlife by acting much like a Brita water filter for our rivers. Like a coral reef, which creates habitat for many other species, freshwater mussel beds enrich aquatic communities. They are also food for otters and other species. Freshwater mussels also have a cultural importance to several Tribes as a First Food.

“Freshwater mussels are often overlooked because they are out of sight, yet they are foundational species that create richer, healthier habitat,” said Sarina Jepsen, petition coauthor and Endangered Species program director at the Xerces Society. “Endangered Species Act protection is critical for a species that faces widespread, and in the case of mass die-offs, unexplained yet devastating threats.”

The Xerces Society has worked for more than a decade to understand and conserve the freshwater mussels that inhabit western U.S. rivers, streams, and lakes by leading research to analyze extinction risk and understand die-offs, educating thousands of wildlife and water managers in mussel survey techniques and conservation, and developing and implementing Best Management Practices for mussels.




Federal Register announcement:

Press release from the U.S. Fish and Wildlife Service:

Western ridged mussel petition:

On the Xerces blog: Working from the (river) bottom up to conserve the western ridged mussel

Conservation guidelines for protecting freshwater mussels: Conserving the Gems of Our Waters

For more information about western freshwater mussels, including the western ridged mussel:


About the Xerces Society
The Xerces Society for Invertebrate Conservation protects the natural world by conserving invertebrates and their habitat. Established in 1971, the Society is a trusted source for science-based information and advice and plays a leading role in protecting pollinators and many other invertebrates. Our team draws together experts from the fields of habitat restoration, entomology, plant ecology, education, pesticides, farming and conservation biology with a single passion: Protecting the life that sustains us. To learn more about our work, please visit or follow us @xercessociety on TwitterFacebook or Instagram.