During artificial rearing, sturgeon can experience disruptions in cell division causing spontaneous autopolyploidy: an unintentional increase in genome size by 1.5 times. In octoploid (8N) Lake Sturgeon, Acipenser fulvescens this results in fertile dodecaploid (12N) offspring, which are more commonly female than male. Mature 12N individuals that successfully spawn with octoploids, produce 10N offspring with poorer fitness and survivorship. I determined the ploidy and biological sex of Lake Sturgeon from wild and hatchery populations in Manitoba, Canada. To compare the incidence of spontaneous autopolyploidy between these environments and investigate sexual bias. Female-specific DNA sequences were used to evaluate the sex of a subset of individuals from each population, using DNA from pectoral fin clips. Blood samples were collected to determine ploidy based on measures of erythrocyte modal nuclei volume, and DNA content. These measures assume that erythrocyte size is representative of genome size, but do not account for extrinsic factors. Therefore, I further investigated temperature, photoperiod, and stocking density affects on the size, shape, abundance, and hemoglobin concentration of erythrocytes. These factors, which were assessed in a separate group of juveniles following 30-days of exposure to one of four treatments: low density (~ 0.2 kg/m2) at 16°C and 12:12 light: dark photoperiod; high density (~ 0.67 kg/m2) at 16°C and 12:12; low density at 20°C and 24:0; and high density at 20°C and 24:0. One 12N individual, which was female, was found in the University of Manitoba hatchery population. Modal nuclei volume was significantly different between all populations, except two which were reared in the same environment. Although most erythrocyte measures were resilient to the environmental changes, modal nuclei volume was sensitive to increased temperature and photoperiod. The incidence of a single 12N individual supports the need for ploidy determinations prior to release of hatchery individuals. With the data suggesting those determinations be made comprehensively, considering the physical and physiological environment of the individuals being sampled. To my knowledge, this is the first study to establish reference values for erythrocyte morphometry in multiple populations of Lake Sturgeon.