HR: 13:45h
AN: B53B-02    [Abstracts]
TI: Influences of fluctuating flows on spawning habitat and recruitment success
AU: * Orth, D J
EM: dorth@vt.edu
AF: Virginia Polytechnic Institute and State University, Fisheries and Wildlife Sciences, 100 Cheatham Hall, Blacksburg, VA 24061-0321 United States
AU: Krause, C W
EM: cwkrause@yahoo.com
AF: Virginia Polytechnic Institute and State University, Fisheries and Wildlife Sciences, 100 Cheatham Hall, Blacksburg, VA 24061-0321 United States
AU: Novinger, D C
EM: dovind@mdc.gov
AF: Virginia Polytechnic Institute and State University, Fisheries and Wildlife Sciences, 100 Cheatham Hall, Blacksburg, VA 24061-0321 United States
AB: Over the 50 years of daily peak power generation, no ramping restrictions, and loss of gravel due to operations of Philpott Dam, on Smith River, has created a wider, rectangular-shaped channel, with steeper banks. The pattern caused by channel degradation, tributary headcutting, bank erosion, and downstream aggradation has limited the length of productive habitat to between 3 and 10 river kilometers from the dam. Here the channel appears to contain key habitats where we found the highest redd densities, abundance, and spawner biomass for brown trout (Salmo trutta). Recruitment of brown trout to the fishable size classes is constrained by the daily hydropower peaking operations. The number of young brown trout produced each year was strongly related to the average magnitude of the peak flow and the duration of generation flows. Magnitude of peak flows also depressed abundance of native fishes. Although, brown trout actively removed fine sediment via redd construction and spawning, thereby increasing gravel permeability, the fine sediments from tributaries and bank erosion rapidly intruded into the spawning gravel in downstream reaches of the river. We recommend mitigating the effects of fluctuating releases from Philpott Dam through a combination of flow management and habitat improvement.
DE: 9810 New fields (not classifiable under other headings)
SC: Biogeosciences [B]
MN: 2005 Joint Assembly