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Ebonyshell (Fusconaia ebena)



Ebony shell (Fusconaia ebena), a mussel listed as Endangered. It is found in the western and southern part of Wisconsin in large rivers and is usually on a gravel, sand, or mud bottom in water at least six feet deep where the current is swift. Only very old relic individuals have been found since 1920. Although five fish have been reported as hosts, it is believed that the skipjack herring was the primary host.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Ebonyshell (Fusconaia ebena). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.

Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.

Documented locations of Fusconaia ebena in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusEND
Federal Status in Wisconsinnone
State RankS1
Global RankG4G5
Tracked by NHIY

Species guidance

Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).

Identification: Shell is subelliptical, thick, and inflated. Epidermis is dark brown or black and without rays. In young shells the epidermis is yellowish followed by bright green and brown. Beaks are elevated and turned forward. Posterior end rounded, dorsal margin evenly curved, and the surface has many concentric ridges. Length to 4 inches (10.2 cm) or more.

Habitat: Inhabits large rivers and is usually on a gravel, sand, or mud bottom in water at least six feet deep where the current is swift.

State Distribution: Occurs in the Mississippi River, the lower Wisconsin and the St.Croix.

Phenology: Host fish is skipjack herring (Alosa chrysochloris). Breeding season is June to September. Black crappie (Pomoxis nigromaculatus), white crappie (P. annularis), and largemouth bass (Micropteris salmoides) have been used by the mussels in June as well.

Management Guidelines: The primary host fish for this species, the skipjack herring, has nearly been eliminated in the upper Mississippi due to locks and dams restricting migration from the Gulf of Mexico. Prior to the building of the locks and dams, the ebony shell was the most abundant species in the Mississippi River. It is rarely, if ever, encountered today. It was used extensively for the pearl button industry because of its high quality, thick "mother-of-pearl" shell. Habitat destruction and river pollution have resulted in mussel declines. Protection of habitat and improvements in water quality along with restriction of dredging, impoundments, sand and gravel mining, and navigational improvements would benefit this species. The development of fish runways to facilitate the movement of host species through or around dams could help to protect the ebony shell.




Photo ©  Illinois Natural History Survey.

Last revised: Tuesday, February 19, 2019