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Raistakka, J. E. (1973). Conduit structure for migrating fish. Official Gazette of the United States Patent Office. November 20, 1973. Patent Number 3,772,891. 916: 857-858.
Migrating fish may circumvent a dam by use of a conduit enabling their passage upstream and downstream. The conduit terminates in segments projecting in a submerged manner outward into the river; the segments are flexible to a degree to permit vertical positioning of the conduit ends for optimum fish ingress and egress. It is closed from the atmosphere to prevent the addition of nitrogen to the water passing through the conduit. A constant gradient and constant flow facilitate fish passage. Spaced along the conduit are series of flow disrupting projections which cause the water to form areas of eddying water currents providing resting areas for the fish. Fish attracting substances are fed into the conduit water to help overcome the natural tendency of fish to shy away from the entry of the conduit.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://www.umesc.usgs.gov/URL: http://www.umesc.usgs.gov/data_library/fisheries/fish_passage/raistakka.html
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