Effects of hydrologic change and variability on upstream limits of stream fish distribution

Project Leader: 
Research Partners: 
Benjamin Letcher, Andrew Whiteley
Project Fellows: 
Status: 
Ongoing
Science Themes: 

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 native range, and use hydrologic models and GIS analysis to predict future upstream limits and consequent habitat distributions under climate change scenarios.

We have identified key climate-associated drivers of brook trout occupancy, abundance and population dynamics. High summer temperatures appear to decrease brook trout growth and survival across a wide range of environmental contexts, and factors associated with relatively low summer water temperatures (including high levels of forest cover) increase probability of occupancy. In contrast, the relationship between streamflow, population dynamics, and occupancy was more context-dependent requiring additional research to establish robust relationships and forecasts. Across five watersheds in the northeast, we have so far found little evidence of reduced occupancy or abundance in small (< 1 km2) watersheds, suggesting that these very small headwaters could serve as vital refugia in a changing climate.

This project provides a framework for managers to predict status of coldwater fisheries resources and differences in relative resilience among streams, watersheds and regions.

Publications: 
Presentations: 
  • Brook trout population dynamics: Integrated modeling across scales and data types. Presented, American Fisheries Society Annual Meeting, Aug 17 2014 Quebec City, Ben Letcher, Keith Nislow et al.

  • Science-management partnerships for brook trout conservation in the context of climate change.  USDA Forest Service Partnership Office Webinar Series 2/12/2015.

  • Forests, landscapes, and fishes in a changing regional environment. Northern States Research Cooperative Webinar Series. April 30, 2015

  • Climate-mediated portfolio effects for headwater resident trout. Annual Meeting of the American Fisheries Society of America, Portland, OR. August 16-20 2015. Keith Nislow.

  • Management of populations and habitats int he contesxt of climate-driven changes in disturbance regimes. University of Connecticut Seminar Series, October 30th 2015. 

Other: