Life history organization of native trout in a large river network

Potamodromous cutthroat trout express multiple life history strategies, linking seasonal habitats with movement across spatiotemporal scales.  Much of the research on these life history strategies has been conducted in smaller systems where the total habitat for each strategy may be contained within a few small streams.  In larger river systems, the same life history strategies exist, but little is known about the spatiotemporal extent of the stream network used by these strategies or the behavioral variability that may exist within each strategy.  In order to explore the life history organization of native Snake River finespotted cutthroat trout Oncorhynchus clarki behnkei in the upper Snake River below Jackson Lake Dam, we surgically implanted radio transmitters in 248 cutthroat trout and monitored their movement patterns for a year.  All cutthroat trout spawning occurred in side channels of the Snake River (fluvial) and tributaries or spring creeks complexes (fluvial-adfluvial), but there was substantial variability in the timing and location of spawning activity and in pre and post-spawning migration patterns.  We are currently examining the effects of stream network topology and instream habitat variables on the life history patterns observed in this study.