Nearshore Fish Species Richness and Species–Habitat Associations in the St. Clair–Detroit River System

Shallow water riparian zones of large rivers provide important habitat for fishes, but anthropogenic influences have reduced the availability and quality of these habitats. In the St. Clair–Detroit River System, a Laurentian Great Lakes connecting channel, losses of riparian habitat contributed to impairment of fish populations and their habitats. We conducted a seine survey annually from 2013 to 2019 at ten sites in the St. Clair and Detroit rivers to assess riparian fish communities, and to identify habitat attributes associated with fish species richness and catches of common species. We captured a total of 38,451 fish representing 60 species, with emerald shiner Notropis atherinoides composing the largest portion of the catch. We used an information-theoretic approach to assess the associations between species richness and catches of 33 species with habitat variables (substrate, shoreline vegetation types, and aquatic macrophyte richness). Sand, cobble, and algal substrates and shoreline vegetation were important predictors of species richness based on a multimodel inference approach. However, habitat associations of individual species varied. This work identified manageable habitat variables associated with species richness, while identifying potential tradeoffs for individual species. Further, this work provides baselines for development and evaluation of fish community and shoreline habitat restoration goals.

Space use of juvenile and subadult yellow perch (Perca flavescens) in the Detroit River using acoustic telemetry: incorporating variable detection ranges in vegetated areas

Understanding the space use of fishes in early life stages provides information that can contribute to effective fisheries management; however, it can be difficult to track fish in shallow, densely vegetated areas. Using acoustic telemetry, 60 subadult yellow perch (Perca flavescens) were tagged and monitored in a vegetated area of the Detroit River (May-Nov 2018). Variable detection range from submerged aquatic vegetation (SAV) was incorporated in estimates by applying a spatio-temporal correction to aid with interpretation of seasonal changes in activity space. Although subadult yellow perch were commonly detected in the array, demonstrating the importance of SAV habitat (mean detection residency index: 0.85), 60% of individuals were not detected following August, the period with highest activity space estimates, likely due to seasonal movements and predation. Individuals were more commonly detected during the daylight hours compared to night, but activity peaked at crepuscular periods. This study provided spatial information about the often-overlooked early life history of yellow perch, increasing the ecological information available for a species of management and conservation interest in the Great Lakes.