For the field test, lamprey were tagged with visible elastomer implants based on small (89 millimeter or less) and large (92 mm or more) size categories and stocked into mesh enclosures over fine or coarse sediment. The system used a hydraulic eductor (also known as a Venturi valve) to create suction so that sediment and lamprey avoided passage through the pump impeller. We evaluated the injury rate, survival, and burrowing capability of lamprey following passage through the dredge system and used collection of lamprey from water without sediment as a control. Director, Western Fisheries Research CenterĪ portable suction-dredge and sluice-box system were used to collect larval lampreys ( Entosphenus tridentatus and Lampetra spp.) from fine and coarse sediment in field and laboratory tests.
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