Endangered Species
Midwest Region



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Endangered Species Program

Conserving and restoring threatened and endangered species and their ecosystems


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Bringing Species Back from the Brink of Extinction

Augmenting Northern Riffleshell and Clubshell Mussels into the Darby Watershed


Photo of a clubshell mussel shell. Photo by Brant E. Fisher


Photo by Brant E. Fisher

Nearly 300 species of mussels inhabit freshwater rivers and lakes in North America. This is the richest diversity of mussels found in the world. Freshwater mussels are sedentary, long-lived (some live over 100 years) mollusks that live in sediments and filter water to feed. Because they are filter-feeders, mussels are excellent indicators of the health of lakes and rivers.


Listed as endangered in 1993, the clubshell and northern riffleshell mussels currently occur in only 5 percent of their historic range. The populations that have managed to hang on are small and isolated from each other. Augmenting these wild populations with captive-propagated stock is necessary if we want to recover these species.


In 2006, an Endangered Species Act grant was awarded to the Ohio Department of Natural Resources to propagate and restore both species to the Darby and St. Joseph River watersheds. Other partners in this project include Columbus Zoo & Aquarium, the Ohio State University and the Franklin County Metro Parks.


The goal of this captive propagation and augmentation project is to bolster existing populations and reestablish the species in historic sections of their range, resulting in the potential to reclassify these species from Endangered to Threatened. Without augmentation, the clubshell and northern riffleshell mussels face a slow slide to extinction.


During the first year of the project, the partnership developed an augmentation plan, reared juveniles of a surrogate species and selected augmentation sites. In addition, we piloted augmentation for the northern riffleshell in Big Darby Creek.


For the first time in Ohio history, endangered mussels were returned to the wild. Juvenile northern riffleshells were released into the Big Darby Creek just south of the main entrance to the Batelle-Darby Metro Park.




Last updated: October 10, 2018