Document Category: Habitat

Radio telemetry of stocked muskellunge (n = 6) and wild northern pike (n = 6) was used to track late summer and fall movements from a common release point in a known shared nursery bay to test the hypothesis that age-1 northern pike and stocked muskellunge segregate and have different habitat affinities. Water depth, temperature, substrate and aquatic vegetation variables were estimated for each muskellunge (n = 103) and northern pike (n = 131) position and nested ANOVA comparisons by species indicated differences in habitat use. Muskellunge exhibited a greater displacement from the release point and used habitat in shallower water depths (mean = 0.85 m, SE = 0.10) than northern pike (mean = 1.45 m, SE = 0.08). Both principal components analysis (PCA) and principal components ordination (PCO) were used to interpret underlying gradients relative to fish positions in two-dimensional space. Our analysis indicated that a separation of age-1 northern pike and muskellunge occurred 7 d post-release. This first principal component explained 48% of the variation in habitat use. Northern pike locations were associated with deeper habitats that generally had softer silt substrates and dense submersed vegetation. Muskellunge locations post-acclimation showed greater association with shallower habitats containing firmer sandy and clay substrates and emergent vegetation. The observed differences in habitat use suggest that fine-scale ecological separation occurred between these stocked muskellunge and wild northern pike, but small sample sizes and potential for individual variation limit extension of these conclusions. Further research is needed to determine if these patterns exist between larger samples of fishes over a greater range of habitats.

Loss or alteration of habitat, especially reproductive habitat, is considered to be a major cause of a decline of native muskellunge populations. Active habitat management programs specifically for muskellunge are virtually nonexistent. This paper summarizes muskellunge habitat needs and problems and suggest guidelines for its management.

Adult muskellunge are strongly associated with submergent vegetation while juveniles seem to prefer emergents; both are associated with woody debris such as submerged tree tops, stumps and loges in rivers and littoral zones of lakes. Dissolved oxygen (DO) depletion from accumulation of flocculent organic mucks and dense aquatic vegetation in spawning areas has been associated with poor natural reproduction. Invasion of formerly exclusive muskellunge waters by northern pike has also been associated with the decline of natural muskellunge populations.

Proposed muskellunge habitat management guidelines include control of northern pike populations, maintenance of balanced fish populations, identification of spawning areas and acquisition of adjacent lands, monitoring of DO at spawning sites and rehabilitation of unsuitable substrates, timber management of riparian areas adjacent to spawning areas and management of watershed to maintain high water quality.

We synthesize results from a number of studies to determine in muskellunge (Esox masquinongy) spawning habitat is predictable. Specific objectives are to (1) evaluate characteristics of spawning habitat in a number of different systems; (2) determine if spawning habitat can be predicted from data on land cover, geology and physical characteristics in the lake or river; and (3) compare spawning habitat in inland lakes and some Great Lakes locations. In inland lakes, muskellunge preferred to spawning over fine sediments near emergent and submersed vegetation in protected bays or shoreline, but bay and calm shoreline habitat is not always available and may be degraded so they may end up spawning over open sand, gravel or coarse particulate organic matter and spawning in areas without vegetation. For objective two, the best performing maxEnt model included shoreline development index, presence of nearby shallow areas, distance from outflowing streams, effective fetch, maximum depth, Carlson’s trophic status index and an indicator of east or west facing shoreline as significant factors predicting spawning locations in inland lakes. Overall, 64% of all observed spawning fell within locations predicted by a model including the most suitable 40% of available habitat for all lakes. For objective three, we compared habitat selection of Great Lakes strain muskellunge with the inland strain. MaxEnt models of habitat for Great Lakes muskellunge included some similar factors like shallow depth and low slope but also included river habitat factors like presence of moderate vegetative cover and woody debris. To conclude, we propose a conceptual model of muskellunge spawning and nursery habitat where survival from egg to larva is limited by water quality, predation on eggs and abundant food sources.

Studies of fine scale habitat characteristics associated with age-0 muskellunge (Esox masquinongy) are uncommon and those that have been conducted have relied on targeted, nonrandom sampling designs which may bias study results. We used a random design to sample age-0 muskellunge and shallow water (< 13. m) habitat features found in the upper Niagara River, New York, during late July through early September 2013-2105. Comparisons of habitat features between sites where muskellunge were present and absent and Firth logistic regression were used to identify important characteristics of muskellunge nursery locations. A total of 15 age-0 muskellunge were collected at 11 of 295 sites sampled. Vallisneria americana was the dominant aquatic vegetation at 10 of 11 sites where muskellunge were collected and sand and mud were the dominant substrate sizes at all locations where age-0 muskellunge were collected. The probability of age-0 muskellunge presence was positively related to the proportion of the water column occupied by aquatic vegetation. Despite sampling nearly 300 sites, the small number of age-0 muskellunge collected limited the types of analyses that could be performed. However, our results provide evidence that shallow water areas with abundant V. Americana should be conserved or resortred to provide reaering habitat for muskellunge in the upper Niagara River. IN future studies, samples sizes of age-0 muskellunge in the upper Niagara River. In future studies, sample sizes of age-0 muskellunge may be increased while maintaining a probability sampling design, by randomly sampling within pre-defined areas that contain habitat features identified at sites where muskellunge were present in our study.

Conserving and restoring muskellunge (Esox masquinongy) spawning habitat are essential for maintaining self-sustaining populations. A Maxent model was developed based on presence and background data to investigate the relationship between the occurrence of spawning muskellunge and habitat features in the upper Niagara River. Muskellunge spawning points (n = 15) were determined by direct observation of spawning pairs. Model inputs were based on micro-habitat features collected at each spawning point and a sample of 250 background habitat points. The full model was reduced to a four variable model to remove uninformative variables and reduce overfitting and redundancy. Model performance was evaluated based on the mean test gain of cross-validated models (n = 15). Model outputs identified aquatic macrophyte/algae coverage as the most important habitat feature at spawning locations. The relative probability of muskellunge spawning increased with the percent rank of total aquatic macrophyte/algae coverage, water velocity, and water depth and it was highest at points with muddy-sand to sand substrates. Mean test gain (0.68; SE = 0.52) of the cross-validated models indicated that the likelihood of an average muskellunge spawning point was nearly two times greater than an average background point. Results from this research advance our knowledge of muskellunge reproductive ecology, while providing scientists and managers with quantitative measures to guide habitat conservation and restoration.

Summer nursery habitats of Great Lakes muskellunge were studied during July and August, 1981. The “typical” habitat was occupied by young-of-year (YOY) muskellunge about 50 mm long and by five other fish species, the most abundant being largemouth bass, pumpkinseed and yellow perch. Each habitat was comprised of eight families of emergent and floating vegetation and nine species of submergent vegetation. Sedge (Cyperaceae) was the most abundant emergent family while bushy pondweed (Najax flexilis), muskgrass (Chara sp) and variable pondweed (Potamogeton gramineus) were the predominant submergent species. Emergent vegetation was dense in a narrow band along the shore where submergent vegetation was sparse. Off shore habitat consisted of a wider band of less dense emergent and floating vegetation and increased bottom cover of submergent vegetation. Shoreline residents often alter littoral areas and their activities may restrict muskellunge production by reducing macrophytes in critical spawning and nursery habitats. Fishery management of southern Georgian Bay can use the “typical” nursery area description to identify potentially important habitats and possibly mitigate the impacts of proposed alterations.

This document is part of the Habitat Suitability Index (HSI) model series which provides habitat information useful for impact assessment and habitat management. Several types of habitat information are provided. The Habitat Use Information section is largely constrained to those data that can be used to derive quantitative relationships between key environmental variables and habitat suitability. This information provides the foundation for the HSI model and may be useful in the development of other models more appropriate to specific assessment or evaluation needs. The HSI Model section documents the habitat model and includes information pertinent to its application. The model synthesizes the habitat use information into a framework appropriate for field application and is scaled to produce an index value between 0.0 (unsuitable habitat) and 1.0 (optimum habitat). The HSI Model section includes information about the geographic range and seasonal appl ication of the model, its current verification status, and a list of the model variables with recommended measurement techniques for each variable. The model is a formalized synthesis of biological and habitat information published in the scientific literature and may include unpublished information reflecting the opinions of identified experts. Habitat information about wildlife species frequently is represented by scattered data sets collected during different seasons and years and from different sites throughout the range of a species. The model presents this broad data base in a formal, logical, and simplified manner. The assumptions necessary for organizing and synthesizing the species-habitat information into the model are discussed. The model should be regarded as a hypothesis of species-habitat relationships and not as a statement of proven cause and effect relationships. The model may have merit in planning wildlife habitat research studies about a species, as well as in providing an estimate of the relative suitability of habitat for that species. User feedback concerning model improvements and other suggestions that may increase the utility and effectiveness of this habitat-based approach to fish and wildlife planning are encouraged.

A questionnaire sent to the chief fishery staff members of each of the U.S. states and Canadian provinces provided the basic data for estimating habitat occupied by walleyes, saugers, yellow perch, northern pike and muskellunge. Species habitat areas, grouped by size categories within lakes, impoundments and streams were listed by major drainage patterns in 4our east to west and fifteen north to south regional groupings. The present distributional patterns of each species resulting from introduced as well as native populations revealed major concentrations of these species around the Great Lakes. The areas occupied by percids and esocids as a percentage of total freshwater area in North America were 54% for northern pike, 1% for muskellunge, 32% for walleyes, 10% for saugers and 26% for yellow perch. Areas occupied by the five species, as a percentage of total freshwater areas, varied widely in different regions.

For several fish species, increased river discharge has been linked to behavioral changes, including movement towards particular habitats. From 2000 to 2003, we used radiotelemetry to monitor habitat use by 42 muskellunge Esox masquinongy within a 17‐km reach of the New River, Virginia; to evaluate habitat selection; and to determine whether habitat use and selection were affected by discharge. Water depth, occurrence of aquatic vegetation, substrate type, and distance to riverbanks within the study reach were mapped with hydroacoustic and Global Positioning System technologies. Real‐time discharge measurements from an upstream U.S. Geological Survey stream gauge were used to classify fish locations into those made during periods of reduced (<75 m3/s) or increased (>75 m3/s) discharge. Seasonal habitat selection models for the different discharge levels were created using logistic regression. Differences in logistic regression coefficients between models were tested with multivariate chi‐square tests and Bonferroni‐corrected pairwise comparisons. Meta‐analytic averaging of Pearson’s correlation coefficients was used to determine the overall effect size of discharge on habitat use by muskellunge. Overall, muskellunge exhibited a positive selection for deeper habitats; however, discharge was found to significantly affect both habitat use and selection. Habitat use was consistent with the hypothesis that fish moved to shallower habitats (both summer and winter) located closer to riverbanks (winter only) during periods of increased discharge. In terms of habitat selection, selection strengths for variables such as water depth (summer and winter) and distance to shoreline (winter only) generally weakened during periods of increased discharge, indicating that habitat use became more proportionate to availability. Increased movement as a result of increased discharge has been theorized to potentially reduce winter survival of fish because of seasonal energetic limitations. Thus, indirect effects on fish from dam operating modes (e.g., hydropeaking) may be as important as direct effects when evaluating biotic implications of water release schedules.