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Freshwater mussels aren’t usually the first animals on people’s minds when they think of what inhabits our rivers and streams. However, these filter feeders are crucial and fundamental players in all freshwater ecosystems across the country. Due to habitat loss, disturbance, and aquatic barriers they are also now one of the most imperiled groups of species in North America with many mussel species being listed as threatened or endangered under the Endangered Species Act. This is the story of how an abandoned shell collection at a university, three years of planning, collaboration with multiple state and local agencies, and a little luck led to biologists at U.S. Fish and Wildlife Service making a discovery that gave them hope for the status of mussel survival, resilience, and diversity in the Black River.
A peek into the Black River before dredging and invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.
Learn more about invasive species
The Black River, a tributary of the St. Clair River, in Michigan has historically been home to over 30 of Michigan's 42 native freshwater mussel species, including three federally listed mussel species (Rayed Bean, Round Hickorynut, and Northern Riffleshell) and many state listed mussel and fish species (Eastern Sand Darter and Brindled Madtom). One of those federally listed mussel species, the Northern Riffleshell, once maintained a reproducing population in this river. However, after dredging occurred within the upper reaches in the late 1980s, there were reduced expectations for the survival of the mussels living in those areas, including the Northern Riffleshell. In fact, though the other federally listed species are still considered extant in the river, the last live Northern Riffleshell was found in the Black River in 1987.
In 2023, biologists at the Alpena Fish and Wildlife Conservation Office, Detroit River Substation collaborated with a professor at Saginaw Valley State University who possessed a mussel collection from a late colleague. This collection, which had been hidden away for nearly 40 years and needed severe curation, presented a significant opportunity to uncover valuable historical insights into Michigan's river mussel communities. The collection contained thousands of shells that were collected prior to the invasion of zebra and quagga mussels in the early 1990’s, providing a unique record of pre-invasion native freshwater mussel diversity. Over 3,000 shells had been collected from various sites within the Black River in Michigan. To our astonishment, of the 3000 shells, approximately 1,800 were Northern Riffleshells, which is typically underrepresented in most freshwater mussel collections. The sheer number of shells in the collection from the Black River, the historical presence of many listed species, and the prevalence of Northern Riffleshells prompted us to begin planning a comparison of mussel diversity between the 1980’s and present day.
Partners come together to survey the Black River
USFWS and partners performed Black River reconnaissance surveys in 2024 by canoeing 47 miles through the reaches represented in the collection. The survey consisted of noting mussel presence, habitat suitability, water depth, and flow at the 1980's survey sites and additional mussel bed locations. This provided us with a wholistic picture of the Black River mussel diversity and potential shifts in habitat utilization due to numerous disturbances throughout the years. During the recon surveys, we found two fresh dead Northern Riffleshells at one road-stream crossing in the upper reaches of the river, which was a site that was regularly surveyed and largely represented in the collection. Both specimens were around 5 years of age and had likely died recently, one still having soft body tissue attached when collected. With this find and the survey sites from the 1980s, we chose a site about a ½ mile upstream, around where the last Northern Riffleshell was found in the 1987 survey.
In 2025, we conducted three weeks of surveys at the site covering approximately 444m2 with visual-tactile cell searches and excavating 135 0.25m2 quadrats. The Alpena Fish and Wildlife Conservation Office were joined by the Michigan Department of Transportation, Michigan Department of Environment, Great Lakes, and Energy, Friends of the St. Clair Watershed, and Consultant companies as well as the Region 3 Dive Officer and divers from Green Bay Fish and Wildlife Conservation Office and the Detroit International Wildlife Refuge. Within the survey site, we found almost 1200 live mussels consisting of 13 species. An additional 6 species were noted but only found via shell specimens. Of the 19 total species observed, 5 are listed as state special concern, 3 are listed as state threatened or endangered, and 2 are federally endangered.
Despite all odds, these mussels are hanging on
In spite of the multiple habitat barriers, years of dredging, and numerous cases of habitat disturbance over the past 40 years, we found 2 live Northern Riffleshells, one male and one female! This is the first time in almost 40 years a live Northern Riffleshell has been observed and tagged in the Black River. Like many endangered species, the Northern Riffleshell is found in very few places. Prior to this find, it only had approximately four reproducing populations left in the world. The discovery of an extant population in Black River and the historical significance of this system opens doors for future conservation and restoration of not only Northern Riffleshell but the entire freshwater mussel and fish community in the watershed.
This find is exciting news and shows that, despite all odds, these mussels are hanging on. With local help, community awareness and pride, it engages us all to be better stewards for our sessile neighbors that often get forgotten. From a dusty and orphaned collection in desperate need of much love to the rediscovery of globally imperiled species that had been suspected to be lost from Michigan waters, our story shows that even the future of conservation can come from some of the most unassuming places and gives us hope for the future of the Black River.
