Conserving the Nature of America
Press Release
Service Proposes Endangered Species Act Protection for Freshwater Mussel

September 3, 2021


Gary Peeples,, 828/258-3939, ext. 42234


Two pyramid pigtoe shells, one turned to show the outside of the shell, the other turned to show the inside.

Pyramid pigote Credit: Nathan Johnson/USGS

Asheville, N.C. – Following a review of the best available science, the U.S. Fish and Wildlife Service is proposing to list the pyramid pigtoe as threatened under the Endangered Species Act (ESA), along with a proposed 4(d) rule that would tailor protections for the mussel.

Once found in 18 states with 151 known populations from Pennsylvania to Oklahoma, Louisiana to Minnesota, the pyramid pigtoe is now found in only half of those states in 35 known populations.

“The pyramid pigtoe’s range was once so expansive it was a challenge for experts to assess its exact range and overall health. A lot of biologists knew how it was faring in their state or area, but no one was putting all the pieces together,” said Service Regional Director Leopoldo Miranda-Castro. “Working with experts across its range, we determined that the mussel has experienced a dramatic decline and is in danger of extinction.”

Today, the mussel is known to be in Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Ohio, Oklahoma, Tennessee and Virginia. It has disappeared from Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Pennsylvania, West Virginia and Wisconsin.

The pyramid pigtoe grows up to 3.6 inches long and may live up to 45 years. It lives in medium to large rivers, preferring a mixture of sand, gravel and cobble stream bottoms. It has suffered negative impacts from influences common to central U.S. streams, including habitat fragmentation from dams and other barriers, habitat loss, degraded water quality from chemical contamination and erosion, direct mortality from dredging and harvest, and the proliferation of invasive species, such as the zebra mussel, Asian clam and black carp.

The ESA defines a threatened species as one likely to become at risk of extinction (endangered) in the foreseeable future throughout all or a significant portion of its range. Listing would prohibit certain activities that could harm or kill the mussel, except where permitted or exempted. Federally funded or authorized projects would be reviewed for impacts to the pyramid pigtoe, and actions of the federal government may not jeopardize its existence. The listing would make recovery efforts for the mussel eligible for funding under the ESA.

While endangered species are afforded blanket protections, section 4(d) of the ESA allows the Service to issue rules that tailor protections for threatened species. For the pyramid pigtoe, certain actions with a minimal level of disturbance and no anticipated long-term negative impacts would be exempted from ESA prohibitions. These include conservation efforts by the Service or state wildlife agencies, stream channel restoration projects, stream bank restoration projects, and other activities.

The Service will propose critical habitat – areas designated as essential to the pyramid pigtoe – at a later date.

To inform its decision, the Service reached out to species and habitat experts, including biologists with state wildlife agencies and university and federal agency researchers, to compile a range-wide status of the species and project its status into the future. This assessment went through a peer-review process and represents the first comprehensive, range-wide investigation into the mussel’s status.

Although people are far more familiar with saltwater mussels commonly offered in restaurants, the United States is home to a tremendous diversity of freshwater mussels. There are more than 900 species worldwide, with North America being a global center of mussel diversity, with about 300 species. Despite the high amount of diversity, 65% of North American freshwater mussel species are imperiled. Sensitive to pollution, native mussels are indicators of broader stream health – vibrant mussel populations typically reflect a healthy stream. In addition to being indicators of stream health, mussels clean water as they feed, filtering their food from the water column, and with it, sediment and other pollutants.

The U.S. Fish and Wildlife Service will accept comments received or postmarked on or before November 8, 2021. Comments submitted electronically using the Federal eRulemaking Portal ( must be received by 11:59 p.m. Eastern Time on the closing date. Search for Docket No. FWS-R4-ES-2021-0092. We must receive requests for public hearings, in writing, at the address shown in FOR FURTHER INFORMATION CONTACT by October 22, 2021.

FOR FURTHER INFORMATION CONTACT: Janet Mizzi, Field Supervisor, U.S. Fish and Wildlife Service, Asheville Ecological Services Field Office, 160 Zillicoa St., Asheville, NC 28801; telephone (828) 258-3939. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Relay Service at 800–877–8339.

Frequently asked questions

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals, and commitment to public service. For more information on our work and the people who make it happen, visit

For more information on our work and the people who make it happen, visit Connect with our Facebook page, follow our tweets, watch our YouTube Channel and download photos from our Flickr page.