Genetic Differentiation of Lake Sturgeon in the St. Lawrence River

In the Great Lakes water basin, lake sturgeon are at less than one percent of their historic population sizes. A population of lake sturgeon inhabits the saline St. Lawrence Estuary. Lake sturgeon samples were taken from the St. Lawrence River at the mouth of Chaudiere River (south shore of the St. Lawrence River) and the mouth of the Montmorency River (north shore of the St. Lawrence River). Our hypothesis was that lake sturgeon in the estuary are genetically distinct to lake sturgeon further upstream due to adaptation to brackish conditions. DNA was extracted from collected tissue samples. The extracted DNA was quantified and 12 microsatellites were amplified using polymerase chain reactions (PCR). Lake sturgeon samples were compared to previously analyzed populations from further upstream on the St. Lawrence River. Genetic differentiation was calculated between the five different sample locations, and barriers to gene flow were identified. Significant levels of differentiation were detected, but no populations were highly differentiated (F_st< 0.05). Two barriers to gene flow were identified in the river, but the estuary population does not appear to be genetically isolated.