A Genetic Assessment of Missouri's Lake Sturgeon after 30 Years of Restoration Releases

Abstract

AbstractThe 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.