HABITAT USE AND MOVEMENTS OF SHOVELNOSE STURGEON IN POOL-13 OF THE UPPER MISSISSIPPI RIVER DURING EXTREME LOW-FLOW CONDITIONS

We monitored habitat use and movement of 27 adult shovelnose sturgeon in Pool 13 of the upper Mississippi River, Iowa-Illinois, by radio-tel emetry in April through August 1988. Our objective was to determine th e response of this species to unusually low water conditions in the up per Mississippi River in 1988. Most (94%) telemetry contacts were made in 3 habitat types: main channel (50%), main channel border where win g dams were present (29%), and tailwaters of Lock and nam 12 (15%). Ha bitat use in spring was affected by the extreme low flows. We often fo und tagged shovelnose sturgeon in the main channel and tailwaters duri ng the spring period (11 March-20 May) where water velocities were hig hest. This was in contrast to other studies where shovelnose sturgeon did not occupy those areas during years with normal spring flows. Shov elnose sturgeon were typically found in areas with a sand bottom, mean water depth of 5.8 m, and mean bottom current velocity of 0.23 m sec( -1). They occupied areas of swifter current but were not always found in the fastest current in their immediate vicinity. Tagged shovelnose sturgeon tended to remain in the upper, more riverine portion of the p ool, and we observed no emigration from the study pool. Linear total r ange of movement from the tagging site ranged from 1.9 to 54.6 km duri ng the study period.