Habitat and Population Assessments of the Lake Sturgeon (Acipenser fulvescens) Reintroduced to the Upper Tennessee River
Daniel J. Walker  2017.  Ph.D. Dissertation.

The Lake Sturgeon Acipenser fulvescens historically occurred throughout the United States and Canada. However, due to widespread overfishing and habitat loss it was extirpated from much of its range, especially in the lower latitudes. Since the year 2000, fisheries managers have been working to restore this species to the Tennessee and Cumberland Rivers where it has been extirpated since c. 1961. This reintroduction is comprised of annual releases of young-of-the-year Lake Sturgeon reared in head-start aquaculture facilities around the Southeastern U.S., and annual monitoring efforts that track the spread and growth of reintroduced individuals. In 2015, a management plan guiding this reintroduction effort was drafted which included a variety of research needs to assist with and improve the ongoing restoration of this species. Two of these research needs are an assessment of habitats available to and occupied by Lake Sturgeon in the Upper Tennessee River, and a quantitative assessment of population size. In this dissertation, I explain how I addressed these two research needs, and based on the results, I offer management recommendations for the continued success of Lake Sturgeon recovery in the Southeastern U.S. I characterized two important types of habitat relevant to different life stages of the species: spawning habitat and summer holding areas. I also used 5 years of mark-recapture data to generate the first quantitative assessments of population density and size-specific survival. My results indicate that there is ample suitable spawning substrate within the tailwaters I surveyed. I collected detailed measurements of various physical habitat variables from an area suspected to be important summer refugia for this species and describe in detail the physical habitat characteristics of this important area of habitat. I used a population model to evaluate the mark-recapture data, and found that while Lake Sturgeon are persisting in the Upper Tennessee River, many fall into the slowest-growth category. Finally, I used simulations to show that without natural recruitment, current stocking rates are unlikely to reach stated population goals through stocking alone. The information I provide here will be instrumental in aiding the adaptive management of this population.