Westslope Cutthroat Trout Movements Through Restored Habitat In The Nevada Spring Creek Complex, Blackfoot Basin, Montana

Anthropogenic degradation of aquatic habitat has depleted native trout, such as westslope cutthroat trout (Oncorhynchus clarkii lewisi), throughout the American West. In the Blackfoot Basin of western Montana, managing for the recovery of migratory westslope cutthroat trout requires landscape-level conservation, as well as site-specific restoration techniques of spawning and rearing tributaries. Westslope cutthroat trout are now increasing in the Blackfoot River and several streams, including Nevada Spring Creek, where restoration of natural channel, flow and temperature regimes have reestablished aquatic habitat and migration corridors. To examine migratory behavior associated with this population expansion, we tracked the post-restoration spawning movements of 14 adult westslope cutthroat trout from wintering areas in lower Nevada Creek (downstream of Nevada Spring Creek) to spawning and summering areas. Ten migrants moved through Nevada Spring Creek upstream a median distance of 7.7 km (range 7.6 – 16.9) to spawning sites at the headwaters of Wasson Creek through stream reaches where channels were reconstructed, instream flows enhanced and grazing practices improved. Eight of the fish that entered Wasson Creek spawned in a concentrated area upstream of two experimental diversion/fish screens structures located in the main channel of Wasson Creek. Compared to Wasson Creek spawners, the total pre-spawning movements of the remaining four radio-tagged fish were significantly further (median = 51.8 km, range 44.9-63.1, P = 0.001). These four fish moved downstream through Nevada Creek into the Blackfoot River and then ascended upper Blackfoot River before entering two separate spawning tributaries. The results of this telemetry study indicate that restoration that improves habitat and migration corridors can promote the recovery of migratory westslope cutthroat trout and that spring-influenced tributaries like Nevada Spring Creek provide important over-winter habitat for westslope cutthroat trout that spawn and summer elsewhere in the basin.