Fluvial Westslope Cutthroat Trout Movements and Restoration Relationships in The Upper Blackfoot Basin, Montana

Abstract

We telemetered fluvial westslope cutthroat trout (Oncorhynchus clarki lewisi, WSCT) to relate migratory life history traits to restoration opportunities in the upper Blackfoot Basin (upstream of the North Fork confluence) of Montana. Telemetry confirmed life-history similarities to fish of the lower basin but also identified higher fidelity to spawning areas and mainstem pools as well as movements through intermittent channels to headwater spawning areas. Anthropogenic influences limit fluvial WSCT abundance and their ability to reproduce and thus, place sensitive areas of the Blackfoot River environment at increased risk. Road crossings, riparian grazing, and irrigation practices, primarily in tributaries of the Gamet Mountains, adversely influence fluvial WSCT from the tributary to sub-basin scales. Localized life history characteristics demonstrated in the upper Blackfoot River environment confirm the value of fisheries investigations at reach and regional fisheries scales. Understanding local life history strategies is vital when planning fluvial native fish recovery in watersheds of geo-spatial and anthropogenic variability. Telemetry results indicated that WSCT conservation and recovery in the upper Blackfoot basin will rely on restoration of tributaries, protection of intennittent channels, changes in grazing and timber harvest practices on alluvial stream channels, and careful management of private ponds (to avoid hybridization). These assessments identified a fundamental need to work with private landowners for fluvial WSCT recovery at a metapopulation scale to be effective.