Northwest Fisheries Science Center

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Document Type: Chapter or Section
Center: NWFSC
Document ID: 7735
Type of Book: Technical
Section or Chapter Title: Velocity-matching traveling screens for juvenile migrant collection. Report No. 25
Book Title: Fish-Passage Research Program review of progress 1964, Volume III
Author: Daniel W. Bates, John G. VanDerwalker
Editor: Gerald B. Collins, Carl H. Elling (Eds.)
Publication Year: 1964
Publisher: Report of the Accelerated Fish-Passage Research Program to the U.S. Bureau of Commercial Fisheries. Seattle, Washington

In the search for a practical method for collecting juvenile salmonids from rivers and streams, many plans have been conceived and tested.  None of these, however, have been able to cope successfully with the high flows and debris of a major river in flood without excessive cost.

In an attempt to eliminate the need for expensive structures capable of withstanding high flow velocities, a method of guiding fish by the use of suspended velocity-matching visual references was proposed.  The system would utilize moving visual references traveling diagonally across the stream but moving in a downstream direction at a rate equal to the downstream velocity of the stream.  The velocity-matching aspect of the system would actually permit the guiding of fish in stream velocities greater than the maximum swimming speed of the fish.

Because the degree of guiding efficiency that might be expected with moving visual references in turbid, turbulent water was questionable, the velocity-matching concept was extended by the authors for use with a traveling screen that appeared to give promise of greater guiding effectiveness.  The following account describes the fabrication and operation of two velocity-matching traveling screens that were installed for test purposes in the behavioral flume at Carson, Washington; reports on the guiding efficiency obtained; and discusses future potential of the method.