Basis for Former Listing

The Hickorynut (Obovaria olivaria) was historically found in the Minnesota and St. Croix rivers and the Mississippi River below St. Anthony Falls (van der Schalie and van der Schalie 1950), but it is now absent from the Minnesota River (Bright et al. 1990), rare in the St. Croix River (Doolittle 1988; Hornbach et al. 1995), and uncommon and scattered in the Mississippi River (Heath 1989). The range and abundance of this species and its host fish species have been reduced. For these reasons, the Hickorynut was listed as a special concern species in Minnesota in 1996.

  Basis for Delisting

The Minnesota DNR initiated a statewide mussel survey in 1999 that  resulted in a better understanding of the current status and distribution of the Hickorynut in Minnesota. The species is common and widespread within the St. Croix River drainage. The Mississippi River from St. Anthony Falls down to Lake Pepin also supports a healthy population of Hickorynut, which is attributed to improvements in water quality (Minnesota Department of Natural Resources 2012). The Hickorynut could potentially be successfully reintroduced to the Minnesota River drainage if the habitat conditions and water quality improve. Because of the status of the current populations and the expansion of the distribution of the Hickorynut, special concern status is no longer deemed necessary. The Hickorynut was delisted in 2013.

  References and Additional Information

Baker, F. C. 1928. The fresh water mollusca of Wisconsin: part II: Pelecypoda. Wisconsin Geological and Natural History Survey Bulletin No. 70, Part II. University of Wisconsin, Madison. 495 pp.

Bright, R. C., C. Gatenby, D. Olson, and E. Plummer. 1990. A survey of the mussels of the Minnesota River, 1989. Final report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. 106 pp.

Cummings, K. S., and C. A. Mayer. 1992. Field guide to freshwater mussels of the Midwest. Illinois Natural History Survey Manual No. 5. 194 pp.

Doolittle, T. C. J. 1988. Distribution and relative abundance of freshwater mussels in the Saint Croix National Scenic Riverway. Final report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resouces. Unpaged.

Heath, D. J. 1989. A survey of freshwater mussels at the proposed west channel bridge site (U.S. Highways 14, 16, 61) in Houston County, MN and LaCrosse County, WI. Report submitted to Kapur and Associates, Milwaukee, Wisconsin. 6 pp.

Helms and Associates, and Marine Engineering Associates, Inc. 1990. Results of mussel survey conducted at the Burlington Northern Railroad Bridge near Winona, Minnesota. Final report submitted to Johnson Brothers Corporation, Litchfield, Minnesota. 15 pp.

Hornbach, D. J., P. Baker, and T. Deneka. 1995. Abundance and distribution of the endangered mussel Lampsilis higginsi in the lower St. Croix River, Minnesota and Wisconsin. Final report submitted to the U.S. Fish and Wildlife Service, Minneapolis, Minnesota. 68 pp.

Minnesota Department of Natural Resources. 2012. Statement of need and reasonableness. Minnesota Department of Natural Resources. Division of Ecological and Water Resources. St. Paul, Minnesota. 337 pp.

Parmalee, P. W., and A. E. Bogan. 1998. The freshwater mussels of Tennessee. The University of Tennessee Press, Knoxville, Tennessee. 328 pp.

Sietman, B. E. 2003. Field guide to the freshwater mussels of Minnesota. Minnesota Department of Natural Resources, St. Paul, Minnesota. 144 pp.

van der Schalie, H., and A. van der Schalie. 1950. The mussels of the Mississippi River. American Midland Naturalist 44:448-464.

Watters, G. T. 1994. An annotated bibliography of the reproduction and propagation of the Unionoidea (Primarily of North America). Ohio Biological Survey Miscellaneous Contributions No. 1, Columbus, Ohio. 158 pp.