Spawning habitat for muskellunge is far more variable than expected: a review of over 20 years of research

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.