The influence of salinity on ionic concentrations and osmolarity of blood serum in lake sturgeon, Acipenser fulvescens

This study examined the extent to which lake sturgeon, Acipenser fulvescens, regulated serum ion concentrations and osmolarity in relation to ambient salinity. Twenty juvenile lake sturgeon, brood stock from the Moose River in the Hudson Bay drainage basin, were gradually transferred from freshwater to more saline waters at a rate of 2 parts per thousand day(-1). Blood was sampled from fish at 0, 10, 15 and 25 parts per thousand following 48 h acclimation periods. Concentrations of Na+, K+, Cl-, Ca2+ and osmolarity were measured. Experimentation was terminated at 25 parts per thousand due to poor fish health resulting in two mortalities. Within freshwater, lake sturgeon blood serum displays similar osmotic and ionic composition to other North American species of sturgeon. Juvenile lake sturgeon do not appear capable of homeostasis above 15 parts per thousand nor are they tolerant to environments exceeding 25 parts per thousand. Some evidence of greater tolerance to elevated salinities with increased size was noted. The ecological potential for resource exploitation in regions of elevated salinities is discussed.