Winged mapleleaf once enjoyed a greater range in the St. Croix River

Mark C. Hove¹, David J. Heath², Daniel E. Kelner³, Daniel C. Allen¹, Ronald L. Benjamin², Mike Davis³, Russel S. Derhak¹, Kristin M. Swenson¹, Jana E. Thomas¹, and Daniel J. Hornbach¹

¹ Macalester College, Biology Dept., 1600 Grand Avenue, Saint Paul, Minnesota 55105 Hove@macalester.edu, 651.696.6827

² Wisconsin Dept. of Nat. Res., 3550 Mormon Coulee Rd., La Crosse, Wisconsin 54601 HeathD@mail01.dnr.state.wi.us, 608.785.9012

³ Minnesota Dept. of Nat. Res., 500 Lafayette Rd., St. Paul, Minnesota 55155 Dan.Kelner@dnr.state.mn.us, 651.282.2509

At one time the federally endangered winged mapleleaf inhabited at least 34 river systems in 12 states (USFWS 1997). Quadrula fragosa (Conrad 1835) is now thought to occur in select reaches of St. Croix River, Wisconsin, Kiamachi River, Oklahoma, and Bourbeuse River, Missouri. One of the last known reproducing populations occurs in the St. Croix River where the river forms the border between Minnesota and Wisconsin. Until very recently winged mapleleaf were thought to occur only downstream of the St. Croix Falls dam. Doolittle and others conducted a mussel survey of the St. Croix and Namekagon rivers and found that Q. fragosa occupies a relatively small reach of the lower river (Doolittle 1988). Recent evidence suggests the range of winged mapleleaf may extend upstream of the dam (Hove et al. 1999).

This summer we surveyed select sites to better describe the historic and current range of winged mapleleaf in the St. Croix River. A total of 85 sites were surveyed above and below the St. Croix Falls dam. We collected empty winged mapleleaf valves at eleven locations spread throughout the surveyed reach and one live winged mapleleaf 9.6 km downstream of the previously thought downstream edge of its range. Live winged mapleleaf appear to be very rare in the lower half of its range in the St. Croix River. As mentioned in Hove et al. (2001) we found two winged mapleleaf valves upstream of the dam at St. Croix Falls which is a barrier to fish migration. Next summer additional survey work will be conducted in a central reach of the St. Croix River to determine if this species used to or still occurs this far upstream.

We thank Jill Medland, Bob Whaley, and Randy Ferrin and the National Park Service who provided administrative, logistic, and financial support for this project.

Literature Cited

Doolittle, T. C. J. 1988. Distribution and relative abundance of freshwater mussels in the Saint Croix National Scenic Riverway. Report to Cable Natural History Museum - Sigurd Olson Environmental Institute. Ashland, Wisconsin. 230 pp.

Hove, M. C., L. A. Cunningham, K. G. Esse, and D. J. Hornbach. 1999. Range extension of the federally endangered winged mapleleaf: valves collected from upper St. Croix River, Minnesota. Triannual Unionid Report 18: 9.

Hove, M. C., D. C. Allen, R. S. Derhak, K. M. Swenson, J. E. Thomas, and D. J. Hornbach. 2001. Second collection of winged mapleleaf valves from the upper St. Croix River. Ellipsaria 3(2): 11-12.

U.S. Fish and Wildlife Service. 1997. Winged mapleleaf mussel (Quadrula fragosa) recovery plan. Fort Snelling, Minnesota. 69 pp.