Impact of Hydroelectric Facilities on Namew in the Moose Cree Homeland: A Study of Mercury Levels and Dietary Changes
Namew (Moose Cree L dialect for Lake Sturgeon) is a culturally important fish species for Moose Cree First Nation.
Our team — a mix of academic, non-profit, and Indigenous researchers — research the movement, ecology, and health of Namew across the Moose Cree Homeland.
In this study, we tested if Namew’s diet and mercury levels were different in a river with hydroelectric facilities when compared to a free-flowing river. Fish from hydroelectric reservoirs can have high mercury levels in the years after a reservoir is initially created, because of changes in the water chemistry.
Read this open access paper on the FACETS website.
Diet can also influence mercury levels, with mercury increasing as fish eat more carnivorous prey rather than eating herbivorous prey or plants.
We caught Namew using nets and took samples of their blood and fin tissue, then released them back into the river. We analyzed the blood for mercury levels and the fin tissue for different types of carbon and nitrogen, which tell us about their diet.
Our data showed that Namew from the free-flowing river had higher mercury in their blood than fish from the river with hydroelectric facilities, potentially because they were eating different prey.
We also found that Namew’s diet changed downstream of the hydroelectric facilities, possibly because our team had trouble finding bugs along the shoreline downstream of the hydroelectric facilities; this was unlike the free-flowing river, or sites upstream of the hydroelectric facilities, where many bugs were found.
Since the hydroelectric facilities in this study are decades old, our results suggest that any initial increase in mercury levels that may have happened during the reservoir creation have now ceased in this river, and diet is likely a more important factors driving mercury burdens in Namew today.
We will need to do more research to fully understand these differences in diets, and to understand what Namew are eating downstream of the hydroelectric facilities.
Read the paper — The long-term effects of water resource development on blood mercury levels and the trophic ecology of Namew (lake sturgeon, Acipenser fulvescens) by Gretchen L. Lescord, Jennifer Simard, Thomas A. Johnston, Jacob Seguin, Claire E. Farrell, Nelson J. O’Driscoll, and Constance M. O’Connor.
