Genetic Tagging and Parental Genotype Reconstruction for Recovering Lower Missouri River Pallid Sturgeon

A conservation propagation program for endangered Pallid Sturgeon (Scaphirhynchus albus) in the lower Missouri River was implemented in the early 1990’s to supplement stocks and reduce the likelihood of localized extinction.  Hatchery-origin progeny are currently stocked exclusively into the river reach from which their parents were collected; however, past practices allowed stocking of offspring of genetically distinct upper Missouri River broodstock into the lower Missouri River.  Stocking large numbers of hatchery-reared offspring from a small number of upper Missouri River parents is potentially detrimental to pallid sturgeon recovery because it increases the likelihood of inbreeding, outbreeding, and domestication. Some of these offspring have sexually matured and are being recaptured as part of the lower Missouri River broodstock collection program.  While all stocked fish were physically tagged upon release, long term tag retention has been low.  We are using genetic tagging to identify hatchery-origin pallid sturgeon by matching them to known parental crosses.  Where parental tissue samples are absent, we are reconstructing these parental genotypes using tissue samples from offspring of known crosses.  Our findings indicate that a large fraction of adult pallid sturgeon in the lower Missouri River are unmarked hatchery offspring derived from a small number of upper basin parental crosses.