Progress towards restoration of self-sustaining populations of lake trout in the Laurentian Great Lakes has been slow. Adequate survival of stocked yearlings to maturity suggests potential recruitment bottlenecks exist between spawning and the yearling life stage, possibly related to an inability to select spawning habitats suitable for egg incubation. However, little is known about the fundamental features of lake trout spawning habitats or the criteria by which it is selected. This information gap was addressed using a novel acoustic telemetry-based approach whereby sampling effort was apportioned among habitats known to have been encountered during the spawning period based on behavioral data from tagged adult lake trout. Among sites encountered by lake trout on three spawning reefs in northern Lake Huron, physical characteristics and egg survival were compared between habitats positive and negative for egg deposition. Widespread egg deposition was confirmed on all three reefs, but variables measured (substrate diameter, homogeneity, interstitial depth, and slope) were unable to fully explain the habitat selection observed, suggesting other variables may have been important. Based on an in situ habitat bioassay, egg survival did not differ between habitats that received egg deposition and those that did not, suggesting the supply of spawning habitat may exceed demand in this area. Further, lake trout spawned in habitats inconsistent with the commonly-accepted lake trout spawning habitat paradigm, including previously undescribed boulder-associated habitats. These unconventional habitats not only received egg deposition, but also produced viable juveniles, forcing us to rethink, adapt, and expand our conceptual understanding of suitable trout spawning habitat.
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