Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 7937
Title: Imprinting salmon and steelhead trout for homing, 1982
Author/Editor: Emil Slatick, Lyle G. Gilbreath, Jerrel R. Harmon
Publication Year: 1983
Publisher: National Marine Fisheries Service
Contracting Agency: Bonneville Power Administration. Portland, Oregon
Contract Number: DE-AI79-81-BP27891-M001

The National Marine Fisheries Service, under contract to the Bonneville Power Administration, began conducting research on imprinting Pacific salmon and steelhead for homing in 1978.  The juvenile marking phase was completed in 1980; over 4 million juvenile salmon and steelhead were marked and released in 23 experiments.  The primary objectives were to determine:  1. a triggering mechanism to activate the homing imprint, 2. if a single imprint or a sequential imprint is necessary to assure homing, and 3. the relationship between the physiological condition of fish and their ability to imprint.  Research in 1982 concentrated on:  1. recovering returning adults from previous experiments, 2. analyzing completed 1979 steelhead and chinook salmon experiments, and 3. preliminarily analyzing 1980 fall chinook salmon experiments.  Six experimental groups are discussed:  two steelhead, two spring chinook salmon, and two fall chinook salmon.  In four test groups, survival was enhanced by the imprinting-transportation procedures.  Homing back to the hatchery area was partly successful in two test groups, and generally, unless there were extenuating circumstances (eruption of Mount St. Helens, disease problem, etc.), greater returns to user groups were evident.