Paddlefish Polyodon spathula and three sturgeon species are present in the upper Mississippi River; of these four species, two are commercially and recreationally important (Paddlefish and Shovelnose Sturgeon Scaphirhynchus platorynchus), and two are protected under federal or state endangered species laws (Pallid Sturgeon S. albus and Lake Sturgeon Acipenser fulvescens). Before management strategies can be implemented, quantification of movement patterns is necessary to determine the appropriate spatial scale for management. To increase the available relevant information, we investigated broad‐scale movement patterns of the above species in the upper Mississippi River by using telemetry. All four species were capable of long‐range (>300‐km) movements, and these movements were cued by the changing river stages and water temperature. Ultimately, our data suggest that sturgeon and Paddlefish movement patterns are highly variable, with fish moving freely among rivers (e.g., the Mississippi, Missouri, Illinois, Ohio, and Des Moines rivers) across many political boundaries and encompassing multiple regulatory agencies. This migratory nature can lead to portions of the population being subject to harvest in multiple management units, affecting population dynamics, biology, harvest, and management/recovery in both the natal area and in the harvest areas. To effectively manage or recover these highly mobile fish populations, interjurisdictional collaboration will be necessary.

Ecologists have a limited understanding of the rangewide variation in movement behavior in freshwater fishes, but recent expansion of biotelemetry allows biologists to investigate how fish movement can help to predict behavioral shifts in response to changing environments. The Lake Sturgeon Acipenser fulvescens is a wide‐ranging, migratory, coolwater species, making it a candidate species for studying patterns in movement ecology. We conducted a literature review and meta‐analysis of seasonal movement data compiled from 38 Lake Sturgeon telemetry studies in North America to build an understanding of spatiotemporal variation in movement behavior. Lake Sturgeon movement studies were underrepresented for low‐latitude populations in the Mississippi, Missouri, and Ohio/Tennessee River basins. Highest movement usually occurred during spring spawning migrations, whereas other populations exhibited their highest movement in the fall, potentially in order to overwinter near spawning grounds. Our meta‐regression analysis indicated that latitude or summer maximum temperature best predicted standardized mean difference between spring and summer movement in Lake Sturgeon populations across the species’ range. Our results suggest that Lake Sturgeon populations at lower latitudes and those that experience warmer summer temperatures have lower summer movement relative to spring movement. Managers may use this information to prioritize actions promoting the conservation of seasonally important habitats for the continued recovery of migratory coolwater fish (e.g., Lake Sturgeon) that potentially experience stressful thermal conditions.

Spatio‐temporal movement patterns of aquatic organisms drive many ecological processes. However, dams block migrations and alter the hydrologic and thermal regimes influencing movement behaviour of freshwater fishes. In North America, many recovering southern Lake Sturgeon populations occur in rivers with hydroelectric dams, but few studies have examined the impact of hydrologic alteration on their seasonal movements. We conducted a 3‐year telemetry study of 96 adult and subadult Lake Sturgeon to compare their migratory responses to temperature and hydrology in adjacent regulated and unregulated tributaries of the Missouri River. Many other populations of Lake Sturgeon use tributaries primarily for spring spawning; however, in our study, Lake Sturgeon used Missouri River tributaries during 78% of the year. Differences in river size, hydrologic and thermal regimes in the regulated Osage River may have contributed to the greater year‐round residency, later initiation, more frequent directional changes and longer duration of spring migrations compared to the unregulated Gasconade River. Lake Sturgeon made spring upstream migrations at temperatures of 13–19°C and elevated discharges in both rivers. However, Osage River migrants responded less to changes in discharge or temperature during spring migrations, especially those that overwintered at upstream locations. Fall tributary migrations occurred in the Osage River at rising or high discharges but were uncommon in the Gasconade River. Our identification of the influences of abiotic variables on the timing, duration and extent of Lake Sturgeon seasonal migrations can help guide management of habitat and hydrology in regulated rivers to recover migratory fishes globally.

The Lake Sturgeon Acipenser fulvescens is native to three major watersheds in the USA: the Great Lakes, Hudson Bay, and Mississippi River drainages. However, they have declined across much of their range due to overfishing, pollution, and major river alterations. After their near extirpation in Missouri, the Missouri Department of Conservation initiated a reintroduction program to restore the Lake Sturgeon in the state's largest waterways. From 1984 to 2015, offspring originating from Lake Winnebago (1984–2001) and from upper Mississippi River tributaries (2004–2015) were reared in captivity and released into portions of the Mississippi and Missouri rivers. After 32 years of restorative releases, we screened Lake Sturgeon samples from the state of Missouri by using 11 microsatellite loci and mitochondrial DNA control region sequences. We examined overall genetic diversity and genetic structure of Lake Sturgeon captured in the Mississippi and Missouri rivers for differences between rivers and among groups within rivers. We found high levels of genetic diversity within both rivers, with very little genetic differentiation between them. Higher‐than‐average relatedness within sample groups and heterozygote excess were consistent with the pattern expected from stocked fish and suggested that closely related fish may have aggregated at stocking sites. We detected two genetic groups in Missouri, reflecting the change in stock source. Haplotypes that may be unique to the Mississippi and Ohio River systems were observed at very low frequencies. Though largely the product of stocking, reproductively mature Lake Sturgeon will likely have sufficient genetic diversity and will have experienced selection pressures in Missouri's large rivers, making them the most appropriate source for further supplementation if it is deemed necessary. We recommend continued research and monitoring of reproductive habits and preservation of multiple spawning sites to continue the long path toward a self‐sustaining Lake Sturgeon population in Missouri's waters.

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