Muskellunge Esox Masquinongy Populations Research Articles

Pronounced Genetic Structure and Site Fidelity among Native Muskellunge Populations in Lake Huron and Georgian Bay

AbstractConservation and management issues related to genetic diversity and stock structure of native populations of Muskellunge Esox masquinongy have largely been unexplored. In Lake Huron's North Channel and Georgian Bay, Muskellunge populations have been impacted by historical commercial fisheries, recreational fisheries, loss of spawning habitat, historical water quality issues, and ecosystem changes. To determine the spatial genetic structure of native Muskellunge in Lake Huron and Georgian Bay, spawning adults were sampled from 10 sites in the North Channel and eastern Georgian Bay. Genotyping with 20 microsatellite DNA loci showed substantial spatial genetic structure, with significant pairwise divergences among spawning sites. Individual‐ and population‐based analyses revealed hierarchical population structuring, with strong patterns of spawning site fidelity and isolation by distance; very low levels of dispersal and gene flow over historical and contemporary timescales were indicated. Estimation of effective population sizes highlighted the limited genetic resources that are present in these localized populations. The present results show that Muskellunge in Lake Huron and Georgian Bay consist of multiple small populations with limited ranges and high site fidelity and should be managed accordingly.Received February 28, 2016; accepted July 1, 2016 Published online October 11, 2016

Evaluation of temperature-selection differences among juvenile muskellunge originating from different latitudes

Genetic differences among muskellunge Esox masquinongy populations are related to residence in major river drainages, suggesting the existence of divergent stocks. By use of radio-telemetry we compared different seasonal and diel temperature selection in a southern Illinois reservoir for three geographically and genetically distinct stocks of age-2 muskellunge from throughout the latitudinal range of the species. Muskellunge from the Upper Mississippi River drainage were represented by the Leech Lake, Minnesota, population and the Ohio River drainage was represented by the Cave Run Lake, Kentucky, population. Progeny from North Spring Lake, Illinois, an interstock, or mixed-origin stock, were also evaluated. No differences in temperature selection were observed among stocks of juvenile muskellunge across seasons or diel periods. The seasonal mean temperatures of the water varied significantly—spring 21.7°C, summer 28.4°C, and fall 14.8°C, with an overall average temperature of 24.1°C, in agreement with previously published values obtained in laboratory trials. This lack of different temperature-selection patterns among stocks is in contrast with other life-history characteristics, for example growth, metabolism, and conversion efficiency, which have been shown to differ among populations and stocks.

Lake Characteristics Influencing Spawning Success of Muskellunge in Northern Wisconsin Lakes

We determined the physical, chemical, biological, and land use characteristics that distinguish northern Wisconsin lakes with self-sustaining populations of muskellunge Esox masquinongy from lakes where stocking is required to maintain populations. Lakes that supported self-sustaining muskellunge populations were characterized by fewer shoreline alterations and by spawning habitats with softer, organic-nitrogen-rich sediments. Lakes that required stocking had extensively developed shorelines. The direction of water level change during the spawning period, percentage of spawning area sediment covered by woody debris, number of deadfall trees per kilometer of shoreline, and percentage of shoreline that was totally developed were the most important variables for classifying the level of muskellunge reproduction a lake could support. A linear discriminant function correctly classified 83% of the lakes with self-sustaining muskellunge populations and 89% of the lakes requiring stocking to sustain or enhance muskellunge populations. Lake managers wishing to use muskellunge stocking programs to reestablish self-sustaining populations should critically review each candidate lake by considering our model and that of Dombeck et al. (1986).

Trends in Wisconsin's Muskellunge Fishery

Abstract Wisconsin's populations of muskellunge Esox masquinongy provide an important recreational fishery. Our objectives were to (1) evaluate progress of the Wisconsin Department of Natural Resources muskellunge management plan, (2) examine subsequent changes in the fishery, and (3) evaluate Wisconsin's muskellunge waters classification system. With the goal of maintaining viable populations and a trophy fishery, the 1979 plan endorsed more restrictive harvest regulations, an increased supply of muskellunge fishing opportunities, and increased data collection. Since the 1980s, muskellunge fishing opportunities have increased 75% in terms of lake acres and 51% in terms of stream miles. Hatchery production and stocking efficacy have improved to the point where the department needs to reevaluate current stocking practices. With the establishment of a shorter season, a higher statewide minimum length limit, and an increased use of special regulations, harvest regulations have become progressively more restr...

Effects of Length Limits on Muskellunge in Bone Lake, Wisconsin

Minimum length limits are a commonly used management tool for protecting fisheries from exploitation and for improving population size structure. However, little is known about the effects of minimum length limits on populations of muskellunge Esox masquinongy. We monitored changes in the muskellunge population in Bone Lake, a 1,781-acre lake in northwest Wisconsin over a 31-year period (1964–1995) during which time length limits were changed from 30 in to 34 in and from 34 in to 40 in. These changes were compared with population changes in nearby Deer Lake (807 acres), where the length limit remained at the statewide minimum of 32 in. Mean length of adult muskellunge in Bone Lake increased from 31.3 in in 1964 to 36.0 in in 1995. Adult (≥30-in) muskellunge abundance in Bone Lake increased more than five-fold during the study and reached a density of 0.99 fish/acre. Abundance of larger (≥38-in) muskellunge increased 269% following minimum length limit increases between 1982 and 1995. Relative weight (Wr) of Bone Lake muskellunge decreased during the study, suggesting intraspecific competition for food resources. The muskellunge population in Deer Lake also had positive increases in size structure, but the increases were not as great as those in Bone Lake, and population abundance did not change. Results from this study suggest that high minimum length limits can increase abundance and mean length of a muskellunge population, but biologists need to consider long-term effects on the fish community if high densities are achieved.

The Influence of Spawning Habitat on Natural Reproduction of Muskellunge in Wisconsin

Abstract Many of Wisconsin's native populations of muskellunge Esox masquinongy exhibit declining reproductive success and failing natural recruitment. As a result, self-sustaining populations of muskellunge are diminishing. This study focused on spawning habitat factors that influence egg development and survival and, consequently, the reproductive success of muskellunge. Muskellunge spawning habitat characteristics in lakes with self-sustaining populations were compared with spawning habitat characteristics in lakes that were once self-sustaining but are now maintained by stocking. The hatching success of artificially fertilized eggs was assessed under natural lake conditions. Spawning sites were typically marshy areas in water less than 1 m deep. Characteristics of the spawning habitat influenced successful reproduction. Spawning areas in stocked lakes had low dissolved oxygen (DO; 1.2–5.4 mg/L) at the substrate–water interface, whereas self-sustaining lakes had more variable DO (0.5–9.6 mg/L) with som...

Comparison of Food Consumption, Growth, and Metabolism among Muskellunge: An Investigation of Population Differentiation

Abstract We conducted laboratory evaluations of food consumption, growth, and metabolic rate as functions of water temperature (5–27.5°C) to examine how the young of year in six populations of muskellunge Esox masquinongy (Kentucky, Minnesota, New York, Ohio, St. Lawrence River, and Wisconsin) from three drainages might perform under various thermal regimes. Relative food consumption (g·g−1·d−1) and growth (g·g−1·d−1) were similar among populations at lower temperatures (5 and 10°C, but at higher temperatures (15–27.5°C) fish from Wisconsin and Ohio had higher consumption and faster growth rates than fish from Kentucky and the St. Lawrence River. Metabolic rates increased with temperature from 0.08 mg O2·g−1·h−1 at 5°C to 0.25 mg O2·g−1·h−1 at 25°C, but few differences in metabolic rates were observed among populations at any temperature. Although we found bioenergetic differences among muskellunge from these populations, they could not be explained solely in terms of thermal adaptation or previously defi...