Coldwater stream fishes are widely predicted to move upstream in response to warming downstream river temperatures. However, in the process they may encounter upstream limits, which are likely to be exacerbated by increased hydrologic variability if upstream locations draining small basins switch from perennial to ephemeral flow, with important but currently unknown implications for coldwater habitat and stream fish populations. In this project, we will look at the current determinants of upstream limitation for Eastern Brook Trout in several (8-10 large watersheds) throughout their nativ