Date of Award:

2014

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Advisor/Chair:

Nicholaas W. Bouwes

Abstract

The Bonneville Power Administration (BPA) Fish and Wildlife Program mitigates for impacts of hydroelectric dams on ESA-listed salmon and steelhead populations in the Columbia River Basin (CRB). Considering the sizable investments in mitigation and the diversity of stream habitats within the CRB, there has been a pointed effort to develop and identify meaningful metrics relating to fish populations and trends in their habitat across the CRB. The Integrated Status and Effectiveness Monitoring Program (ISEMP) was developed in 2003 specifically for this purpose, and is tasked with developing and testing strategies for determining the status and trend of salmonid populations and their habitats in the CRB. This thesis was funded by the BPA, ISEMP, Eco Logical Research Inc., the Snake River Salmon Recovery Board, and the Intensively Monitored Watershed project in the Asotin Creek basin with the purpose of investigating the efficacy of foraging modeling as part of a large fish habitat monitoring program. The primary objectives were i) to assess a foraging model's ability to predict fish density in study sites involved in long-term monitoring and ii) to evaluate energetic implications of restoration design and progress after implementation using a foraging model.

To assess the foraging model's ability to predict fish density (objective i), we collected topography, drift, temperature, discharge, and fish population information to support foraging modeling, and we simulated flow patterns, drift, foraging, swimming costs, carrying capacity, and density. We then compared observed and predicted densities in 22 study sites from the John Day and Asotin Creek watersheds:

  • Linear regression between observed and predicted fish densities was significant (R2 = 0.61, p < 0.001).
  • When assuming spatially uniform drift densities and small fish territories, carrying capacity predictions were related to the number of foraging locations simulated, suggesting the model is highly sensitive to territory size assumptions.

To evaluate restoration design and monitor restoration progress (objective ii), we simulated foraging before restoration, after a virtual restoration (carried out using the restoration designs in a GIS environment), and again followinfg restoration implementation. We used raster differencing to compare the "before" results to the virtual restoration results and then the "before" results to the "after" results. Hydraulic and foraging models suggested:

  • Mean net energy intake increased following both simulated and actual restoration.
  • Restoration structures generally slowed water's progress through the study site or caused pooling, both resulting in an increase in energetically favorable areas.
  • Generally, more areas shifted from another state to having an acceptable energy balance than to an unacceptable energy balance.

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