Fine Sediment Removal Greatly Increases Fish Selection of Restored Habitat during Restoration of a Sandy River

We estimated change in habitat attractiveness to Brook Trout (Salvelinus fontinalis) and Sculpin (Cottus spp.) using a mark-recapture methodology and dynamic modelling in the Salmon Trout River, Marquette County, Michigan, before and after a reach scale fine sediment removal. We hypothesized that by removing fine sediments and exposing large substrates (e.g. pebbles and cobbles) we would increase the number of fish selecting the restored habitat (estimated from immigration rates used as a surrogate of habitat preference) relative to two nearby reference reaches.  The restoration coupled with spring floods removed at least 20.18 cubic meters of fine sediments from the restoration reach, which reduced substrate embeddedness and exposed large substrates. We observed increases in immigration rates across all three study reaches after the restoration, however the increase was greatest in the restoration reach (600% and 634% for Brook Trout and Sculpin, respectively). Increases in density were much smaller (13% and 81% for Brook Trout and Sculpin, respectively). If we had relied solely on density as a metric of habitat preference, the impact of the restoration would have been greatly underestimated. Therefore, the use of behavioral metrics (e.g. habitat selection) may be a more sensitive tool for quantifying success of restorations.