Environmental Cues of Spawning Migration into a Confined Wetland by Northern Pike and Common Carp in Lake Erie: Identifying Fine‐Scale Patterns

Abstract

AbstractRestoration of wetlands in the Laurentian Great Lakes is designed to improve numerous ecosystem services including nutrient sequestration, support recreational uses, augment waterfowl habitat, and provide spawning and nursery habitat for fish. These projects often use Northern Pike Esox lucius, as a sentinel species for assessing restoration success because of their obligate use of emergent and submergent vegetation by the early life stages. However, invasive species such as Common Carp Cyprinus carpio also utilize these habitats and can have negative effects. Thus, fostering the use of these wetlands by Northern Pike and limiting access by invasive carp is a common restoration management concern. Using a dual frequency sonar system to observe fish migration in a recently connected Lake Erie coastal wetland, we were able to identify fine‐scale environmental correlates to immigration by each species during early spring. Both species overwhelmingly migrated during daylight hours and against the flow of water that was generated through seiche‐driven water oscillations. However, Northern Pike predominantly immigrated during the initial increase in water temperature immediately after ice‐out; Common Carp also began to enter the wetland at low temperatures shortly after ice‐out, but immigration exhibited a slow exponentially increasing pattern, such that the primary immigration timing differed by almost 30 d. Thus, we demonstrate common fine‐scale spawning migration patterns (i.e., water oscillation effects and time of day) for both species and reinforce the temperature‐correlated differences in spawning migration. Using these results could enable managers of connected wetlands to more precisely and dynamically manage habitat accessibility for desired species like Northern Pike while better regulating invasive Common Carp spawning migration and use of these systems.