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

Abstract

Glacial 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 iceout 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.

Effects of Harvest, Natural Mortality, and Escapement on Reservoir Walleye Populations

“…In our study, weekly estimates of escapement probability ranged from 0.03 with a mean spillway water level of 0.05 m to 0.29 with a spillway level of 0.28 m. Escapement was relatively consistent at water levels up to 0.1 m, after which escapement probability substantially increased. Other studies have found a similar relationship between escapement and discharge (Navarro and McCauley 1993; Weber et al 2013; Weber and Flammang 2019; Meerbeek and Weber 2020), supporting the idea of a discharge threshold that, when passed, leads to dramatic increases in escapement. Armbruster (1962) found that nearly 20,000 Walleye escaped from Berlin Reservoir, Ohio, USA during a 5‐year period, with nearly half of Walleye being mortally wounded during emigration and the majority of escapement occurring during rapid lake level reductions.…”

Using Bioenergetics to Estimate Consumption of Stocked Age‐0 Walleye by a Suite of Piscivores

“…Piscivore assemblages in East Okoboji and West Okoboji lakes include Largemouth Bass, Muskellunge, adult Walleye, Northern Pike, and Smallmouth Bass. Muskellunge and Walleye can move between East Okoboji and West Okoboji lakes, but movement rates between lakes are low (typically <10% annually) and appear to occur primarily in the spring (Meerbeek and Weber 2020; J. Meerbeek, Iowa Department of Natural Resources, unpublished data). Thus, intersystem predator movement was likely low during our fall sampling period.…”