Oral Presentation International Conference on River Connectivity (Fish Passage 2018)

A Framework to Evaluate Vulnerability of Upriver Migrants to Existing Hydroelectric Infrastructure and Climate Change (#89)

Rebecca Flitcroft 1 , Sarah Lewis 2 , Ivan Arismendi 2 , Chante Davis 2 , Guillermo Giannico 2 , Brooke Penaluna 1 , Mary Santelmann 2 , Mohammad Safeeq 3 , Jeff Snyder 4
  1. USDA Forest Service, Adair Village, OREGON, United States
  2. Oregon State University, Corvallis, OREGON, United States
  3. UC Merced, Merced, California, United States
  4. Western Oregon University, Monmouth, Oregon, United States

River systems have been extensively modified by anthropogenic development of uplands and alterations in flow regimes. These changes reduce the capacity of river floodplains to absorb natural geophysical and environmental changes and directly affect life history adaptations that have developed over the millennia for native species. For example, in western North America changes in upslope processes (i.e. fire regimes, forest harvest and associated managements) work in concert with alterations in natural flow and thermal regimes through dams, levees, and floodplain development to change recovery trajectories of river systems. However, existing phenotypic adaptation by native fishes to environmental conditions may not be compatible with alterations to flow and thermal regimes. Climate change may compound this issue by further reducing variability in environmental conditions, both directly and indirectly, thereby inhibiting the full expression of life history diversity present in current populations. We explored expressed behavioral variability in upriver migration and passage for adult Coho Salmon (Oncorhynchus kisutch), an endangered salmon in Washington and Oregon, USA. We combined long-term records of river flow, water temperature, and upstream fish passage in a single visualization, providing strong empirical foundations for understanding upstream behavioral movement and tolerances of this native salmon. We compared current behavioral variability of Coho Salmon to scenarios representing possible future hydrologic conditions associated with a changing climate.  We found that in some locations, the range of environmental conditions in the future is not outside the behavioral variability currently expressed by upstream migrating adult Coho Salmon. However, in some locations, predicted changes in streamflow and temperature occur during times of peak migration and may affect survival of upstream migrants. We discuss management implications and recommendations for action that may expand the capacity of riverscapes to absorb perturbations, thereby allowing for enhanced resilience of native fish populations.