The Effect of River Thermal Regime on Early Life Stage Success in White Sturgeon

The effects of different thermal regimes on incubation and rearing early life stages of white sturgeon were examined in a laboratory study. The Columbia River has been significantly altered by the construction of dams resulting in annual flows and water temperatures that differ from historical levels. We incubated and reared white sturgeon early life stages (eggs, larvae, and juveniles) under two thermal regimes; one mimicking the current, cool water regime of the mid Columbia River downstream from Revelstoke Dam, and one mimicking a warmer regime similar to conditions found further downstream. Results suggest that thermal regimes during incubation influence rate of egg development and may influence size at hatch. However, variation in metrics assessed can be attributed to both maternal and paternal sources. Larvae from the cool thermal regime resisted starvation for significantly longer compared to those from the warm thermal treatment. Finally, juveniles reared in a warm thermal regime were larger and had greater energy reserves at the onset of winter. Results from this study fill important biological gaps that currently hinder conservation planning for white sturgeon in the Columbia River.