Canvasback Mortality from Illegal Hunting on the Upper Mississippi River

Study Area

Our 646-ha study area on Lake Onalaska in Navigation Pool 7 of the Upper Mississippi River (Fig. 1) was open to hunting. Lake Onalaska is a 3,036-ha backwater immediately above Navigational Lock and Dam 7 near La Crosse, Wisconsin. Water depth in Lake Onalaska ranges from 0.6 to 2.5 m, and mean depth is about 1.3 m. The lake has been used extensively by canvasbacks during fall migration since the mid-1960's (W. E. Green, USFWS, Upper Miss. River National Wildl. and Fish Refuge, Winona, Minn., unpubl. rep., 1974; Serie et al. 1983; Korschgen 1989). A 2,960-ha area has been closed to hunting during the waterfowl hunting season since 1958. Boaters have been encouraged to voluntarily circumnavigate a 1,390-ha waterfowl-avoidance area (Fig. 1) established in 1986 in an attempt to further reduce disturbance to waterfowl; it is an area closed to hunting but open to boating.

Fig. 1. Lake Onalaska study area, Navigation Pool 7, Upper Mississippi River, 1991-1992.

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