Assessing the Magnitude of Effect of Hydro-Electric Facilities on Lake Sturgeon Abundance in Ontario

Dams and lake sturgeon have a long history, and within the last century this relationship has been extended to hydro-electric facilities. Given the migratory nature of lake sturgeon, dams generally have an adverse effect on their populations. This effect can be exacerbated with hydro-electric facilities as flows and water levels are dramatically altered. Qualitatively, the effects of hydro-electric facility operations are known. However, despite the elongated history between the two, these effects have not been quantified (i.e., how much are lake sturgeon affected). The objective of this study was to ascertain the magnitude of effect different hydro-electric facility operating regimes have on lake sturgeon abundance. Also, it was to quantify the effectiveness of remedial actions intended to offset these effects. A standardized index netting program was conducted throughout Ontario in unimpounded rivers and rivers managed as run-of-the-river, peaking and winter reservoir systems. Overall, 23 rivers were assessed throughout the province sampling 362 lake sturgeon. The magnitude of effect of the hydro-electric facilities on lake sturgeon abundance was quantified as large. Partitioned among water management regimes, this effect was lowest on run-of-the-river systems and greatest on both peaking and winter reservoir systems. Adults appear to be most affected in peaking systems whereas the magnitude of effect for juveniles were least affected by run-of-the-river systems and equally affected in peaking and winter reservoir systems. Despite the potential effects of dams on lake sturgeon, only two hydro-electric facilities have employed remedial actions directed at them in Ontario. A spawning shoal was constructed downstream of Chenaux Generating Station on the Ottawa River in December 2008, however the effectiveness of this project would not yet be detectable. Flow augmentation during the spawning period was employed in the Kaministiquia River from 2004 – 2011. The magnitude of effect on this population was considerable less than observed for peaking systems suggesting that it the management actions benefited lake sturgeon, specifically juveniles. However, this only represents one location. Substantially more mitigation and monitoring is required to determine true effectiveness.