Midwest Fish & Wildlife Conference 2018

AUTHORS. Michael Moore, Craig Paukert - University of Missouri Cooperative Fish and Wildlife Research Unit

ABSTRACT.  Lake Sturgeon are a migratory fish species that feed in lentic habitats and migrate up tributaries in the spring to spawn. However, some southern Lake Sturgeon populations are confined to lotic systems. Few studies in the Mississippi River basin have documented tributary use outside of the spawning season by Lake Sturgeon. However, both historical and anecdotal evidence suggests that mid-sized tributaries are important year-round Lake Sturgeon habitat in the Missouri River basin. From 2015-2017, we implanted 54 Lake Sturgeon in two Missouri River tributaries with acoustic telemetry tags and monitored their movement from May-September 2017 through manual and passive tracking. The study area, which spanned over 1300 river km of the Missouri and Mississippi River basins in Missouri, was based off a network of 37 acoustic receivers. We divided our study area into 16 zones: nine in the Osage, two in the Gasconade, four in other Missouri River Tributaries, one in the main-stem Missouri, and one in the main-stem Mississippi. Our results show that all of our tagged Lake Sturgeon were present within a tributary during some point of the study period and overall tagged fish spent 70% of the study period in tributaries, and 20% remained in the tributaries during the entire summer. Lake Sturgeon congregated in two distinct holding areas in the Osage River July and August that were associated with tributary mouths and deepwater habitat caused by dredging. These areas may serve as important refuge habitats as water temperatures approached 30°C, which is near their thermal maximum. Information from this ongoing study on tributary use, habitat selection, site fidelity, and movement rates will aid in the recovery of Lake Sturgeon at the southern margin of their range.