Lake sturgeon (Acipenser fulvescens), which are now protected from harvest, areconsidered rare in the upper Mississippi River and little information is available on the remainingpopulations. Transmitters were implanted into 31 lake sturgeon from two sites in the upperMississippi River to describe their habitats and movement. The areas surrounding the taggingsites were core areas for both groups of lake sturgeon based on the high use (about 50% oflocations by group) and frequent return to these areas by many of the tagged fish. Core areascontained sites with unique hydraulic characteristics, such that depositional substrates werecommon yet flow was present; these areas probably provide important feeding habitat for lakesturgeon. Minimal geographical overlap in range occurred between groups, suggesting that riverreaches and associated core areas were unique to groups or substocks of fish. Lake sturgeonexhibited complex movement behaviours and had ranges of 3-198 km (median, 56 km) during thestudy. Tagged fish moved both downstream and upstream through upper Mississippi Rivernavigation dams. However, dams appeared to be intermittent barriers to upstream passagebecause upstream passage events (10 fish, 19 passages) were fewer than downstream events(13 fish, 35 passages). Extensive use of the Wisconsin River by one group of lake sturgeontagged in the upper Mississippi River has implications regarding management of a threatenedpopulation that transcends regulatory boundaries. Our study indicates that lake sturgeon in theupper Mississippi River system share many movement and habitat use characteristics withpopulations in other systems. However, significant data gaps preclude development of cogentmanagement strategies, including information on population numbers and dynamics, identificationof spawning areas, relations between groups, and assessment of the effects of commercialnavigation.