Muskellunge (Esox masquinongy) movement patterns and habitat use in the St. Louis River Estuary and southwestern Lake Superior

Abstract

The St. Louis River Estuary is a designated Area of Concern by the Environmental Protection Agency due to severe environmental degradation. Uncertain is the spatial ecology of muskellunge (Esox masquinongy), an indicator species, in relation to both degraded and restored habitats. I collaborated with the Minnesota and Wisconsin Department of Natural Resources to collect genetic samples and use passive acoustic telemetry to track 60 Muskellunge in the St. Louis River Estuary and southwestern Lake Superior for 15 months. Genetic analysis revealed that the river is utilized by two genetic strains (Wisconsin and Minnesota) that were previously stocked to restore a nearly extirpated population. According to ANOVA, Muskellunge tended to move upstream in the spring, downstream and into Lake Superior throughout summer, and to the middle river during fall and winter. Males and females spent significantly more time in the upper and lower rivers, respectively. Movements were influenced by strain in that hybrids and WI strain spent more time in the upper and middle river, and the MN strain spent more time in Lake Superior. A Random Forest model indicated that Lake Superior use was related to strain (the MN strain made up 80% of individuals using Lake Superior), but not sex or body length. Lastly, a Negative Binomial Hurdle model determined that Muskellunge were detected in restored sites more often than in non-restored, poor quality sites. A better understanding of Muskellunge ecology in the St. Louis River Estuary will guide future management and restoration efforts of Muskellunge in the St. Louis River Estuary and other areas of the Great Lakes.