Occupancy rates of river otters (Lontra canadensis) in the St. Louis River Area of Concern

The St. Louis River Area of Concern (AOC), an estuarine system along the northeastern Minnesota-Wisconsin border, experienced significant ecological disturbances and degradation from unregulated industrial development during the 19^th and 20^th centuries. Recent restoration and remediation efforts in the AOC have led to substantial improvements in water quality, habitat, and fisheries populations. However, the status of wildlife populations following restoration efforts in the AOC remain largely unknown. We used remote cameras to estimate occupancy rates of river otters Lontra canadensis in the AOC and at two reference areas that had not been subjected to historical degradation. Because river otters occupy a high trophic level within these systems, we hypothesized that they would be an effective indicator species of overall habitat quality and recovery. Using data collected from June 2015 to February 2016, we developed single-season occupancy models for both summer and winter seasons. We found no differences in occupancy between the AOC and the reference sites, suggesting that river otter populations within the AOC were comparable to those in unaffected areas.  Our results indicate that habitat restoration and remediation efforts in the St. Louis River estuary have been successful in promoting healthy wildlife populations.