Muskellunge Survival, Interbasin Movement, and Emigration in a Simple and a Complex Interconnected Glacial Lake

Abstract

AbstractGlacial lakes can display a wide range of morphometries that may affect fish movements and population dynamics. Muskellunge Esox masquinongy is a popular sportfish that is long‐lived and occurs at low densities, making population abundance susceptible to sources of fish loss. Yet, factors influencing Muskellunge survival, movement, and emigration in lakes of different morphometric complexities are unknown. We used capture histories of nearly 5,700 individual adult (age ≥ 3; ≥610 mm) Muskellunge collected from a simple (single shallow lake, bowl‐shaped basin with simple shoreline) and a complex (multiple basins with greater habitat diversity) lake basin over 17 years to quantify survival, interbasin movement, and emigration from these systems and evaluate if these parameters were related to population density or water level metrics. Adult Muskellunge annual survival within the interconnected lake chain varied through time and among connected lakes (range = 0.57–0.95), whereas survival was similar among years in the simple lake basin (0.90; 95% CI = 0.85–0.96). Muskellunge movement probabilities within an interconnected lake chain ranged from 0.02 to 0.22 and increased in two systems but decreased in one system with maximum ice‐out water level over crest. Similarly, annual Muskellunge emigration ranged from 0.02 to 0.16 from an interconnected lake chain and from 0.00 to 0.28 in a simple lake and increased in both systems with increasing water levels following ice‐out. These results demonstrate that Muskellunge movement within and emigration from lakes as a function of ice‐out water levels can be an important source of fish loss (either temporary or permanent) from glacial lakes. Information on movement and emigration may help managers mitigate these losses via supplemental stocking or reduced harvest quotas, whereas constructing barriers may be a necessary component of Muskellunge management in other lake systems.